49 CFR Part 393 — Parts and Accessories Necessary for Safe Operation

PART 393—PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Authority: 49 U.S.C. 31136, 31151, 31502; sec. 1041(b), Pub. L. 102-240, 105 Stat. 1914, 1993; secs. 5301 and 5524, Pub. L. 114-94, 129 Stat. 1312, 1543, 1560; and 49 CFR 1.87. Source: 33 FR 19735, Dec. 25, 1968, unless otherwise noted. Editorial Note: Nomenclature changes to part 393 appear at 66 FR 49874, Oct. 1, 2001. Subpart A—General Source: 53 FR 49384, Dec. 7, 1988, unless otherwise noted. § 393.1 Scope of the rules in this part. (a) The rules in this part establish minimum standards for commercial motor vehicles as defined in § 390.5 of this title. Only motor vehicles (as defined in § 390.5) and combinations of motor vehicles which meet the definition of a commercial motor vehicle are subject to the requirements of this part. All requirements that refer to motor vehicles with a GVWR below 4,536 kg (10,001 pounds) are applicable only when the motor vehicle or combination of motor vehicles meets the definition of a commercial motor vehicle. (b)(1) Every motor carrier and its employees must be knowledgeable of and comply with the requirements and specifications of this part. (2) Every intermodal equipment provider and its employees or agents responsible for the inspection, repair, and maintenance of intermodal equipment interchanged to motor carriers must be knowledgeable of and comply with the applicable requirements and specifications of this part. (c) No motor carrier may operate a commercial motor vehicle, or cause or permit such vehicle to be operated, unless it is equipped in accordance with the requirements and specifications of this part. (d) No intermodal equipment provider may operate intermodal equipment, or cause or permit such equipment to be operated, unless it is equipped in accordance with the requirements and specifications of this part. (e) The rules in this part do not apply to “pipeline welding trucks” as defined in 49 CFR 390.38(b). [70 FR 48025, Aug. 15, 2005, as amended at 73 FR 76823, Dec. 17, 2008; 81 FR 47721, July 22, 2016] § 393.3 Additional equipment and accessories. The use of additional equipment or accessories in a manner that decreases the safety of operation of a commercial motor vehicle in interstate commerce is prohibited. Nothing contained in this subchapter shall be construed to prohibit the use of additional equipment and accessories, not inconsistent with or prohibited by this subchapter, provided such equipment and accessories do not decrease the safety of operation of the motor vehicles on which they are used. [78 FR 58484, Sept. 24, 2013] § 393.5 Definitions. As used in this part, the following words and terms are construed to mean: Aggregate working load limit. Agricultural commodity trailer. Air brake system. Air-over-hydraulic brake subsystem. Anchor point. Antilock Brake System ABS (1) Sensing the rate of angular rotation of the wheels; (2) Transmitting signals regarding the rate of wheel angular rotation to one or more controlling devices which interpret those signals and generate responsive controlling output signals; and (3) Transmitting those controlling signals to one or more modulators which adjust brake actuating forces in response to those signals. Article of cargo. Auxiliary driving lamp. Bell pipe concrete. Blocking. Boat trailer. Bracing. Brake. Brake power assist unit. Brake power unit. Brake tubing/hose. Chassis. Clearance Lamps. Container chassis trailer. Converter dolly. Crib-type log trailer Curb weight. Dunnage. Dunnage bag. Edge protector. Electric brake system. Emergency brake. Emergency brake system. Fifth wheel. Frame vehicle. Friction mat. Front fog lamp. Fuel tank fitting. g. 2 2 Grommet. Hazard warning signal. Head lamps. Heater. Heavy hauler trailer. (1) Its brake lines are designed to adapt to separation or extension of the vehicle frame; or (2) Its body consists only of a platform whose primary cargo-carrying surface is not more than 1,016 mm (40 inches) above the ground in an unloaded condition, except that it may include sides that are designed to be easily removable and a permanent “front-end structure” as that term is used in § 393.106 of this title. Hook-lift container. Hydraulic brake system. Identification lamps. Integral securement system. Lamp. Length of a manufactured home. License plate lamp. Longwood. i.e., Low chassis vehicle. (2) A motor vehicle, not described by paragraph (1) of this definition, having a chassis which extends behind the rearmost point of the rearmost tires and which has a lower rear surface that meets the guard configuration requirements of § 393.86(b)(1). Major tread groove Manufactured home above Metal coil Multi-piece windshield. Parking brake system. Play. Pulpwood trailer. Rail vehicle. Rear extremity. Reflective material. Reflex reflector. Road construction controlled horizontal discharge trailer Saddle-mount. (1) Upper-half. Upper-half (2) Lower-half. Lower-half (3) King-pin. King-pin Service brake system. Shoring bar. Shortwood. Sided vehicle. Side extremity. Side marker lamp (Intermediate). Side marker lamps. Special purpose vehicle. (2) A motor vehicle, not described by paragraph (1) of this definition, having work-performing equipment that, while the motor vehicle is in transit, resides in or moves through the area that could be occupied by the horizontal member of the rear impact guard, as defined by the guard width, height and rear surface requirements of § 393.86(b)(1). Split service brake system. Steering wheel lash. Stop lamps. Surge brake. Tail lamps. Tiedown. Tow bar. Tractor-pole trailer. Trailer kingpin. Turn signals. Upper coupler assembly. Upper coupler plate. Vacuum brake system. Vehicle safety technology. Void filler. Well. Wheels back vehicle. (2) A motor vehicle, not described by paragraph (1) of this definition, whose rearmost axle is permanently fixed and is located such that the rearmost surface of the tires (of the size recommended by the vehicle manufacturer for the rear axle) is not more than 610 mm (24 inches) forward of the transverse vertical plane tangent to the rear extremity of the vehicle. Width of a manufactured home. Windshield. Working load limit (WLL). [53 FR 49384, Dec. 7, 1988, as amended at 63 FR 8339, Feb. 18, 1998; 63 FR 24465, May 4, 1998; 64 FR 47707, Sept. 1, 1999; 67 FR 61224, Sept. 27, 2002; 68 FR 56208, Sept. 30, 2003; 70 FR 48026, Aug. 15, 2005; 71 FR 35832, June 22, 2006; 72 FR 9870, Mar. 6, 2007; 81 FR 47731, July 22, 2016; 81 FR 65574, Sept. 23, 2016; 86 FR 62111, Nov. 9, 2021; 87 FR 12604, Mar. 7, 2022; 89 FR 90623, Nov. 18, 2024] § 393.7 Matter incorporated by reference. (a) Incorporation by reference. Federal Register. (b) Matter or materials referenced in part 393. (1) Auxiliary Upper Beam Lamps, Society of Automotive Engineers (SAE) J581, July 2004, incorporation by reference approved for § 393.24(b). (2) Front Fog Lamp, SAE J583, August 2004, incorporation by reference approved for § 393.24(b). (3) Stop Lamps for Use on Motor Vehicles Less Than 2032 mm in Overall Width, SAE J586, March 2000, incorporation by reference approved for § 393.25(c). (4) Stop Lamps and Front- and Rear-Turn Signal Lamps for Use on Motor Vehicles 2032 mm or more in Overall Width, SAE J2261, January 2002, incorporated by reference approved for § 393.25 (c). (5) Tail Lamps (Rear Position Lamps) for Use on Motor Vehicles Less Than 2032 mm in Overall Width, SAE J585, March 2000, incorporation by reference approved for § 393.25(c). (6) Tail Lamps (Rear Position Lamps) for Use on Vehicles 2032 mm or More in Overall Width, SAE J2040, March 2002, incorporation by reference approved for § 393.25(c). (7) Turn Signal Lamps for Use on Motor Vehicles Less Than 2032 mm in Overall Width, SAE J588, March 2000, incorporation by reference approved for § 393.25(c). (8) Sidemarker Lamps for Use on Road Vehicles Less Than 2032 mm in Overall Width, SAE J592, August 2000, incorporation by reference approved for § 393.25(c). (9) Directional Flashing Optical Warning Devices for Authorized Emergency, Maintenance, and Service Vehicles, SAE J595, January 2005, incorporation by reference approved for § 393.25(e). (10) Optical Warning Devices for Authorized Emergency, Maintenance, and Service Vehicles, SAE J845, May 1997, incorporation by reference approved for § 393.25(e). (11) Gaseous Discharge Warning Lamp for Authorized Emergency, Maintenance, and Service Vehicles, SAE J1318, May 1998, incorporation by reference approved for § 393.25(e). (12) Reflex Reflectors, SAE J594, December 2003, incorporation by reference approved for § 393.26(c). (13) Standard Specification for Retroreflective Sheeting for Traffic Control, American Society of Testing and Materials, ASTM D 4956-04, 2004, incorporation by reference approved for § 393.26(c). (14) Automobile, Truck, Truck-Tractor, Trailer, and Motor Coach Wiring, SAE J1292, October 1981, incorporated by reference approved for § 393.28. (15) Highway Emergency Signals, Fourth Edition, Underwriters Laboratories, Inc., UL No. 912, July 30, 1979 (with an amendment dated November 9, 1981), incorporation by reference approved for § 393.95(j). (16) American National Standard for Safety Glazing Materials for Glazing Motor Vehicles and Motor Vehicle Equipment Operating on Land Highways-Safety Standard, SAE Z26.1-1996, August 1997, incorporation by reference approved for § 393.62(d). (17) Specification for Sound Level Meters, American National Standards Institute, S1.4-1983, incorporation by reference approved for § 393.94(c). (18) Standard Specification for Strapping, Flat Steel and Seals, American Society for Testing and Materials (ASTM), D3953-97, February 1998, incorporation by reference approved for § 393.104(e). (19) Welded Steel Chain Specifications, National Association of Chain Manufacturers, September 28, 2005, incorporation by reference approved for § 393.104(e). (20) Recommended Standard Specification for Synthetic Web Tiedowns, Web Sling and Tiedown Association, WSTDA-T1, 1998, incorporation by reference approved for § 393.104(e). (21) Wire Rope Users Manual, 2nd Edition, Wire Rope Technical Board November 1985, incorporation by reference approved for § 393.104(e). (22) Cordage Institute rope standards approved for incorporation into § 393.104(e): (i) PETRS-2, Polyester Fiber Rope, 3-Strand and 8-Strand Constructions, January 1993; (ii) PPRS-2, Polypropylene Fiber Rope, 3-Strand and 8-Strand Constructions, August 1992; (iii) CRS-1, Polyester/Polypropylene Composite Rope Specifications, Three-Strand and Eight-Strand Standard Construction, May 1979; (iv) NRS-1, Nylon Rope Specifications, Three-Strand and Eight-Strand Standard Construction, May 1979; and (v) C-1, Double Braided Nylon Rope Specifications DBN, January 1984. (c) Availability. (1) Standards of the Underwriters Laboratories, Inc. Information and copies may be obtained by writing to: Underwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, Illinois 60062. (2) Specifications of the American Society for Testing and Materials. Information and copies may be obtained by writing to: American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428-2959. (3) Specifications of the National Association of Chain Manufacturers. Information and copies may be obtained by writing to: National Association of Chain Manufacturers, P.O. Box 22681, Lehigh Valley, Pennsylvania 18002-2681. (4) Specifications of the Web Sling and Tiedown Association. Information and copies may be obtained by writing to: Web Sling and Tiedown Association, Inc., 5024-R Campbell Boulevard, Baltimore, Maryland 21236-5974. (5) Manuals of the Wire Rope Technical Board. Information and copies may be obtained by writing to: Wire Rope Technical Committee, P.O. Box 849, Stevensville, Maryland 21666. (6) Standards of the Cordage Institute. Information and copies may be obtained by writing to: Cordage Institute, 350 Lincoln Street, # 115, Hingham, Massachusetts 02043. (7) Standards of the Society of Automotive Engineers (SAE). Information and copies may be obtained by writing to: Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, Pennsylvania 15096. (8) Standards of the American National Standards Institute (ANSI). Information and copies may be obtained by writing to: American National Standards Institute, 25 West 43rd Street, New York, New York 10036. (9) [Reserved]. (10) All of the materials incorporated by reference are available for inspection at: (i) Federal Motor Carrier Safety Administration, Office of Bus and Truck Standards and Operations (MC-PS), 1200 New Jersey Ave., SE., Washington, DC 20590-0001; and (ii) The National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. [67 FR 61225, Sept. 27, 2002, as amended at 70 FR 48027, Aug. 15, 2005; 71 FR 35832, June 22, 2006; 72 FR 55703, Oct. 1, 2007; 77 FR 46638, Aug. 6, 2012; 80 FR 59075, Oct. 1, 2015] Subpart B—Lamps, Reflective Devices, and Electrical Wiring § 393.9 Lamps operable, prohibition of obstructions of lamps and reflectors. (a) All lamps required by this subpart shall be capable of being operated at all times. This paragraph shall not be construed to require that any auxiliary or additional lamp be capable of operating at all times. (b) Lamps and reflective devices/material required by this subpart must not be obscured by the tailboard, or by any part of the load, or its covering by dirt, or other added vehicle or work equipment, or otherwise. Exception: The conspicuity treatments on the front end protection devices may be obscured by part of the load being transported. [70 FR 48027, Aug. 15, 2005] § 393.11 Lamps and reflective devices. (a)(1) Lamps and reflex reflectors. (2) Exceptions: (i) The conspicuity material is placed at the locations where reflex reflectors are required by Table 1; and (ii) The conspicuity material when installed on the motor vehicle meets the visibility requirements for the reflex reflectors. (b) Conspicuity Systems. (c) Prohibition on the use of amber stop lamps and tail lamps. Table 1 of § 393.11—Required Lamps and Reflectors on Commercial Motor Vehicles Item on the vehicle Quantity Color Location Position Height above the road surface in millimeters (mm) (with English units in parenthesis) measured from the center of the lamp at curb weight Vehicles for which the devices are required Headlamps 2 White Front On the front at the same height, with an equal number at each side of the vertical center line as far apart as practicable Not less than 559 mm (22 inches) nor more than 1,372 mm (54 inches) A, B, C Turn signal (front). See footnotes #2 and 12 2 Amber At or near the front One on each side of the vertical centerline at the same height and as far apart as practicable Not less than 381 mm (15 inches) nor more than 2,108 mm (83 inches) A, B, C Identification lamps (front). See footnote #1 3 Amber Front As close as practicable to the top of the vehicle, at the same height, and as close as practicable to the vertical centerline of the vehicle (or the vertical centerline of the cab where different from the centerline of the vehicle) with lamp centers spaced not less than 152 mm (6 inches) or more than 305 mm (12 inches) apart. Alternatively, the front lamps may be located as close as practicable to the top of the cab All three on the same level as close as practicable to the top of the motor vehicle B, C Tail lamps. See footnotes #5 and 11 2 Red Rear One lamp on each side of the vertical centerline at the same height and as far apart as practicable Both on the same level between 381 mm (15 inches) and 1,829 mm (72 inches) A, B, C, D, E, F, G, H Stop lamps. See footnotes #5 and 13 2 Red Rear One lamp on each side of the vertical centerline at the same height and as far apart as practicable Both on the same level between 381 mm (15 inches) and 1,829 mm (72 inches) A, B, C, D, E, F, G Clearance lamps. See footnotes #8, 9, 10, 15 & 17 2 Amber One on each side of the front of the vehicle One on each side of the vertical centerline to indicate overall width Both on the same level as high as practicable B, C, D, G, H 2 Red One on each side of the rear of the vehicle One on each side of the vertical centerline to indicate overall width Both on the same level as high as practicable B, D, G, H Reflex reflector, intermediate (side) 2 Amber One on each side At or near the midpoint between the front and rear side marker lamps, if the length of the vehicle is more than 9,144 mm (30 feet) Between 381 mm (15inches) and 1,524 (60 inches) A, B, D, F, G Reflex reflector (rear). See footnotes #5, 6, and 8 2 Red Rear One on each side of the vertical centerline, as far apart as practicable and at the same height Both on the same level, between 381 mm (15 inches) and 1,524 mm (60 inches) A, B, C, D, E, F, G Reflex reflector (rear side). 2 Red One on each side (rear) As far to the rear as practicable Both on the same level, between 381 mm (15 inches) and 1,524 mm (60 inches) A, B, D, F, G Reflex reflector (front side). See footnote #16 2 Amber One on each side (front) As far to the front as practicable Between 381 mm (15 inches) and 1,524 mm (60 inches) A, B, C, D, F, G License plate lamp (rear). See footnote #11 1 White At rear license plate to illuminate the plate from the top or sides No requirements A, B, C, D, F, G Side marker lamp (front). See footnote #16 2 Amber One on each side As far to the front as practicable Not less than 381 mm (15 inches) A, B, C, D, F Side marker lamp intermediate 2 Amber One on each side At or near the midpoint between the front and rear side marker lamps, if the length of the vehicle is more than 9,144 mm (30 feet) Not less tan 381 mm (15 inches) A, B, D, F, G Side marker lamp (rear). See footnotes #4 and 8 2 Red One on each side As far to the rear as practicable Not less than 381 mm (15 inches), and on the rear of trailers not more than 1,524 mm (60 inches) A, B, D, F, G Turn signal (rear). See footnotes #5 and 12 2 Amber or red Rear One lamp on each side of the vertical centerline as far apart as practicable Both on the same level, between 381 mm (15 inches) and 2,108 mm (83 inches) A, B, C, D, E, F, G Identification lamp (rear). See footnotes #3, 7, and 15 3 Red Rear One as close as practicable to the vertical centerline. One on each side with lamp centers spaced not less than 152 mm (6 inches) or more than 305 mm (12 inches) apart All three on the same level as close as practicable to the top of the vehicle B, D, G Vehicular hazard warning signal flasher lamps. See footnotes #5 and 12 2 Amber Front One lamp on each side of the vertical centerline, as far apart as practicable Both on the same level, between 381 mm (15 inches) and 2,108 mm (83 inches) A, B, C 2 Amber or red Rear One lamp on each side of the vertical centerline, as far apart as practicable Both on the same level, between 381 mm (15 inches) and 2,108 mm (83 inches) A, B, C, D, E, F, G Backup lamp. See footnote #14 1 or 2 White Rear Rear No requirement A, B, C Parking lamp 2 Amber or white Front One lamp on each side of the vertical centerline, as far apart as practicable Both on the same level, between 381 mm (15 inches) and 2,108 mm (83 inches) A Legend: Types of commercial motor vehicles shown in the last column of Table 1. A. Buses and trucks less than 2,032 mm (80 inches) in overall width. B. Buses and trucks 2,032 mm (80 inches) or more in overall width. C. Truck tractors. D. Semitrailers and full trailers 2,032 mm (80 inches) or more in overall width except converter dollies. E. Converter dolly. F. Semitrailers and full trailers less than 2,032 mm (80 inches) in overall width. G. Pole trailers. H. Projecting loads. Note: Footnote—1 Identification lamps may be mounted on the vertical centerline of the cab where different from the centerline of the vehicle, except where the cab is not more than 42 inches wide at the front roofline, then a single lamp at the center of the cab shall be deemed to comply with the requirements for identification lamps. No part of the identification lamps or their mountings may extend below the top of the vehicle windshield. Footnote—2 Unless the turn signals on the front are so constructed (double-faced) and located as to be visible to passing drivers, two turn signals are required on the rear of the truck tractor, one at each side as far apart as practicable. Footnote—3 The identification lamps need not be visible or lighted if obscured by a vehicle in the same combination. Footnote—4 Any semitrailer or full trailer manufactured on or after March 1, 1979, shall be equipped with rear side-marker lamps at a height of not less than 381 mm (15 inches), and on the rear of trailers not more than 1,524 mm (60 inches) above the road surface, as measured from the center of the lamp on the vehicle at curb weight. Footnote—5 Each converter dolly, when towed singly by another vehicle and not as part of a full trailer, shall be equipped with one stop lamp, one tail lamp, and two reflectors (one on each side of the vertical centerline, as far apart as practicable) on the rear. Each converter dolly shall be equipped with rear turn signals and vehicular hazard warning signal flasher lamps when towed singly by another vehicle and not as part of a full trailer, if the converter dolly obscures the turn signals at the rear of the towing vehicle. Footnote—6 Pole trailers shall be equipped with two reflex reflectors on the rear, one on each side of the vertical centerline as far apart as practicable, to indicate the extreme width of the trailer. Footnote—7 Pole trailers, when towed by motor vehicles with rear identification lamps meeting the requirements of § 393.11 and mounted at a height greater than the load being transported on the pole trailer, are not required to have rear identification lamps. Footnote—8 Pole trailers shall have on the rearmost support for the load: (1) two front clearance lamps, one on each side of the vehicle, both on the same level and as high as practicable to indicate the overall width of the pole trailer; (2) two rear clearance lamps, one on each side of the vehicle, both on the same level and as high as practicable to indicate the overall width of the pole trailer; (3) two rear side marker lamps, one on each side of the vehicle, both on the same level, not less than 375 mm (15 inches) above the road surface; (4) two rear reflex reflectors, one on each side, both on the same level, not less than 375 mm (15 inches) above the road surface to indicate maximum width of the pole trailer; and (5) one red reflector on each side of the rearmost support for the load. Lamps and reflectors may be combined as allowed in § 393.22. Footnote—9 Any motor vehicle transporting a load which extends more than 102 mm (4 inches) beyond the overall width of the motor vehicle shall be equipped with the following lamps in addition to other required lamps when operated during the hours when headlamps are required to be used. (1) The foremost edge of that portion of the load which projects beyond the side of the vehicle shall be marked (at its outermost extremity) with an amber lamp visible from the front and side. (2) The rearmost edge of that portion of the load which projects beyond the side of the vehicle shall be marked (at its outermost extremity) with a red lamp visible from the rear and side. (3) If the projecting load does not measure more than 914 mm (3 feet) from front to rear, it shall be marked with an amber lamp visible from the front, both sides, and rear, except that if the projection is located at or near the rear it shall be marked by a red lamp visible from front, side, and rear. Footnote—10 Projections beyond rear of motor vehicles. Motor vehicles transporting loads which extend more than 1,219 mm (4 feet) beyond the rear of the motor vehicle, or which have tailboards or tailgates extending more than 1,219 mm (4 feet) beyond the body, shall have these projections marked as follows when the vehicle is operated during the hours when headlamps are required to be used: (1) On each side of the projecting load, one red side marker lamp, visible from the side, located so as to indicate maximum overhang. (2) On the rear of the projecting load, two red lamps, visible from the rear, one at each side; and two red reflectors visible from the rear, one at each side, located so as to indicate maximum width. Footnote—11 To be illuminated when headlamps are illuminated. No rear license plate lamp is required on vehicles that do not display a rear license plate or on the rear of truck tractors while towing a trailer. Footnote—12 Every bus, truck, and truck tractor shall be equipped with a signaling system that, in addition to signaling turning movements, shall have a switch or combination of switches that will cause the two front turn signals and the two rear signals to flash simultaneously as a vehicular traffic signal warning, required by § 392.22(a). The system shall be capable of flashing simultaneously with the ignition of the vehicle on or off. Footnote—13 To be actuated upon application of service brakes. Footnote—14 Backup lamp required to operate when bus, truck, or truck tractor is in reverse. Footnote—15 (1) For the purposes of § 393.11, the term “overall width” refers to the nominal design dimension of the widest part of the vehicle, exclusive of the signal lamps, marker lamps, outside rearview mirrors, flexible fender extensions, and mud flaps. (2) Clearance lamps may be mounted at a location other than on the front and rear if necessary to indicate the overall width of a vehicle, or for protection from damage during normal operation of the vehicle. (3) On a trailer, the front clearance lamps may be mounted at a height below the extreme height if mounting at the extreme height results in the lamps failing to mark the overall width of the trailer. (4) On a truck tractor, clearance lamps mounted on the cab may be located to indicate the width of the cab, rather than the width of the vehicle. (5) When the rear identification lamps are mounted at the extreme height of a vehicle, rear clearance lamps are not required to be located as close as practicable to the top of the vehicle. Footnote—16 A trailer subject to this part that is less than 1829 mm (6 feet) in overall length, including the trailer tongue, need not be equipped with front side marker lamps and front side reflex reflectors. Footnote—17 A boat trailer subject to this part whose overall width is 2032 mm (80 inches) or more need not be equipped with both front and rear clearance lamps provided an amber (front) and red (rear) clearance lamp is located at or near the midpoint on each side so as to indicate its extreme width. [70 FR 48027, Aug. 15, 2005, as amended at 72 FR 32014, June 11, 2007; 72 FR 33562, June 18, 2007; 78 FR 58484, Sept. 24, 2013; 81 FR 47731, July 22, 2016; 81 FR 60634, Sept. 2, 2016; 91 FR 7873, Feb. 19, 2026] § 393.13 Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December 1, 1993. (a) Applicability. (b) Retroreflective sheeting and reflex reflectors. Conspicuity systems (c) Locations for retroreflective sheeting Sides. (2) Lower rear area. (3) Upper rear area. (d) Locations for reflex reflectors Sides. (2) Lower rear area. (3) Upper rear area. [64 FR 15605, Mar. 31, 1999, as amended at 66 FR 30339, June 6, 2001] § 393.17 Lamps and reflectors—combinations in driveaway-towaway operation. A combination of motor vehicles engaged in driveaway-towaway operation must be equipped with operative lamps and reflectors conforming to the rules in this section. (a) The towing vehicle must be equipped as follows: (1) On the front, there must be at least two headlamps, an equal number at each side, two turn signals, one at each side, and two clearance lamps, one at each side. (2) On each side, there must be at least one side-marker lamp, located near the front of the vehicle. (3) On the rear, there must be at least two tail lamps, one at each side, and two stop lamps, one at each side. (b) Except as provided in paragraph (c) of this section, the rearmost towed vehicle of the combination (including the towed vehicles of a tow-bar combination, the towed vehicle of a single saddle-mount combination, and the rearmost towed vehicle of a double or triple saddle-mount combination) or, in the case of a vehicle full-mounted on a saddle-mount vehicle, either the full-mounted vehicle or the rearmost saddle-mounted vehicle must be equipped as follows: (1) On each side, there must be at least one side-marker lamp, located near the rear of the vehicle. (2) On the rear, there must be at least two tail lamps, two stop lamps, two turn signals, two clearance lamps, and two reflectors, one of each type at each side. In addition, if any vehicle in the combination is 80 inches or more in overall width, there must be three identification lamps on the rear. (c) If the towed vehicle in a combination is a mobile structure trailer, it must be equipped in accordance with the following lighting devices. For the purposes of this part, mobile structure trailer (1) When the vehicle is operated in accordance with the terms of a special permit prohibiting operation during the times when lighted lamps are required, it must have on the rear— (i) Two stop lamps, one on each side of the vertical centerline, at the same height, and as far apart as practicable; (ii) Two tail lamps, one on each side of the vertical centerline, at the same height, and as far apart as practicable; (iii) Two red reflex reflectors, one on each side of the vertical centerline, at the same height, and as far apart as practicable; and (iv) Two turn signal lamps, one on each side of the vertical centerline, at the same height, and as far apart as practicable. (2) At all other times, the vehicle must be equipped as specified in paragraph (b) of this section. (d) An intermediate towed vehicle in a combination consisting of more than two vehicles (including the first saddle-mounted vehicle of a double saddle-mount combination and the first and second saddle-mount vehicles of a triple saddle-mount combination) must have one side-marker lamp on each side, located near the rear of the vehicle. (49 U.S.C. 304, 1655; 49 CFR 1.48(b) and 301.60) [40 FR 36126, Aug. 19, 1975, as amended at 47 FR 47837, Oct. 28, 1982; 70 FR 48044, Aug. 15, 2005; 77 FR 59828, Oct. 1, 2012; 80 FR 59075, Oct. 1, 2015] § 393.19 Hazard warning signals. The hazard warning signal operating unit on each commercial motor vehicle shall operate independently of the ignition or equivalent switch, and when activated, cause all turn signals required by § 393.11 to flash simultaneously. [70 FR 48046, Aug. 15, 2005] § 393.20 [Reserved] § 393.22 Combination of lighting devices and reflectors. (a) Permitted combinations. (1) Each required lighting device and reflector conforms to the applicable rules in this part; and (2) Neither the mounting nor the use of a nonrequired lighting device or reflector impairs the effectiveness of a required lighting device or reflector or causes that device or reflector to be inconsistent with the applicable rules in this part. (b) Prohibited combinations. (2) A turn signal lamp must not be combined optically with a stop lamp unless the stop lamp function is always deactivated when the turn signal function is activated. (3) A clearance lamp must not be combined optically with a tail lamp or identification lamp. [39 FR 26908, July 24, 1974] § 393.23 Power supply for lamps. All required lamps must be powered by the electrical system of the motor vehicle with the exception of battery powered lamps used on projecting loads. [70 FR 48046, Aug. 15, 2005] § 393.24 Requirements for head lamps, auxiliary driving lamps and front fog lamps. (a) Headlamps. (b) Auxiliary driving lamps and front fog lamps. (c) Mounting. (d) Aiming. [70 FR 48046, Aug. 15, 2005] § 393.25 Requirements for lamps other than head lamps. (a) Mounting. (b) Visibility. e.g. (c) Specifications. (d) (Reserved) (e) Lamps to be steady-burning. (f) Stop lamp operation. [70 FR 48047, Aug. 15, 2005] § 393.26 Requirements for reflectors. (a) Mounting. (b) Specifications. (c) Substitute material for side reflex reflectors. (d) Use of additional retroreflective surfaces. (1) Designs do not resemble traffic control signs, lights, or devices, except that straight edge striping resembling a barricade pattern may be used. (2) Designs do not tend to distort the length and/or width of the motor vehicle. (3) Such surfaces shall be at least 3 inches from any required lamp or reflector unless of the same color as such lamp or reflector. (4) No red color shall be used on the front of any motor vehicle, except for display of markings or placards required by § 177.823 of this title. (5) Retroreflective license plates required by State or local authorities may be used. [33 FR 19735, Dec. 25, 1968, as amended at 35 FR 3167, Feb. 19, 1970; 53 FR 49397, Dec. 7, 1988; 70 FR 48047, Aug. 15, 2005] § 393.27 [Reserved] § 393.28 Wiring systems. Electrical wiring shall be installed and maintained to conform to SAE J1292—Automobile, Truck, Truck-Tractor, Trailer, and Motor Coach Wiring, October 1981, except the jumper cable plug and receptacle need not conform to SAE J560. The reference to SAE J1292 shall not be construed to require circuit protection on trailers. (See § 393.7(b) for information on the incorporation by reference and availability of this document.) [70 FR 48047, Aug. 15, 2005] § 393.29 [Reserved] § 393.30 Battery installation. Every storage battery on every vehicle, unless located in the engine compartment, shall be covered by a fixed part of the motor vehicle or protected by a removable cover or enclosure. Removable covers or enclosures shall be substantial and shall be securely latched or fastened. The storage battery compartment and adjacent metal parts which might corrode by reason of battery leakage shall be painted or coated with an acid-resisting paint or coating and shall have openings to provide ample battery ventilation and drainage. Wherever the cable to the starting motor passes through a metal compartment, the cable shall be protected against grounding by an acid and waterproof insulating bushing. Wherever a battery and a fuel tank are both placed under the driver's seat, they shall be partitioned from each other, and each compartment shall be provided with an independent cover, ventilation, and drainage. §§ 393.31-393.33 [Reserved] Subpart C—Brakes § 393.40 Required brake systems. (a) Each commercial motor vehicle must have brakes adequate to stop and hold the vehicle or combination of motor vehicles. Each commercial motor vehicle must meet the applicable service, parking, and emergency brake system requirements provided in this section. (b) Service brakes Hydraulic brake systems. (2) Air brake systems. (3) Vacuum brake systems. (4) Electric brake systems. (5) Surge brake systems. (c) Parking brakes. (d) Emergency brakes—partial failure of service brakes Hydraulic brake systems. (2) Air brake systems. (3) Vehicles not subject to FMVSS Nos. 105 and 121 on the date of manufacture. (e) Emergency brakes, vehicles manufactured on or after July 1, 1973. (2) A control by which the driver applies the emergency brake system must be located so that the driver can operate it from the normal seating position while restrained by any seat belts with which the vehicle is equipped. The emergency brake control may be combined with either the service brake control or the parking brake control. However, all three controls may not be combined. (f) Interconnected systems. (2) A motor vehicle to which the requirements of FMVSS No. 105 (S5.1.2), dealing with partial failure of the service brake, applied at the time of manufacture meets the requirements of § 393.40(f)(1) if the motor vehicle is maintained in conformity with FMVSS No. 105 and the motor vehicle is capable of meeting the requirements of § 393.52(b), except in the case of a structural failure of the brake master cylinder body. (3) A bus is considered to meet the requirements of § 393.40(f)(1) if it meets the requirements of § 393.44 and § 393.52(b). [70 FR 48048, Aug. 15, 2005, as amended at 72 FR 9870, Mar. 6, 2007] § 393.41 Parking brake system. (a) Hydraulic-braked vehicles manufactured on or after September 2, 1983. (b) Air-braked power units manufactured on or after March 1, 1975, and air-braked trailers manufactured on or after January 1, 1975. (c) Vehicles not subject to FMVSS Nos. 105 and 121 on the date of manufacture. (2) The parking brake system shall, at all times, be capable of being applied by either the driver's muscular effort or by spring action. If other energy is used to apply the parking brake, there must be an accumulation of that energy isolated from any common source and used exclusively for the operation of the parking brake. Exception: (3) The parking brake system shall be held in the applied position by energy other than fluid pressure, air pressure, or electric energy. The parking brake system shall not be capable of being released unless adequate energy is available to immediately reapply the parking brake with the required effectiveness. [70 FR 48048, Aug. 15, 2005] § 393.42 Brakes required on all wheels. (a) Every commercial motor vehicle shall be equipped with brakes acting on all wheels. This requirement also applies to certain motor vehicles being towed in a driveaway-towaway operation, as follows: (1) Any motor vehicle towed by means of a tow-bar when another motor vehicle is full-mounted on the towed vehicle; and (2) Any saddlemount configuration with a fullmount. (b) Exception. (2) Motor vehicles being towed in a driveaway-towaway operation (including the last truck of triple saddle-mount combinations (see § 393.71(a)(3)) are not required to have operative brakes provided the combination of vehicles meets the requirements of § 393.52. (3) Any semitrailer or pole trailer (laden or unladen) with a gross weight of 1,361 kg (3,000 pounds) or less which is subject to this part is not required to be equipped with brakes if the axle weight of the towed vehicle does not exceed 40 percent of the sum of the axle weights of the towing vehicle. (4) Any full trailer or four-wheel pole trailer (laden or unladen) with a gross weight of 1,361 kg (3,000 pounds) or less which is subject to this part is not required to be equipped with brakes if the sum of the axle weights of the towed vehicle does not exceed 40 percent of the sum of the axle weights of the towing vehicle. (5) Brakes are not required on the steering axle of a three-axle dolly which is steered by a co-driver. (6) Loaded housemoving dollies, specialized trailers and dollies used to transport industrial furnaces, reactors, and similar motor vehicles are not required to be equipped with brakes, provided the speed at which the combination of vehicles will be operated does not exceed 32 km/hour (20 mph) and brakes on the combination of vehicles are capable of stopping the combination within 12.2 meters (40 feet) from the speed at which the vehicle is being operated or 32 km/hour (20 mph), whichever is less. (7) Portable conveyors manufactured prior to 2010 and used by the aggregate industry are not required to be equipped with brakes on all wheels provided: (i) The combination of portable conveyor and towing vehicle meet the performance requirement in 49 CFR 393.52; (ii) The sum of the axle weights of the towed vehicle does not exceed 40 percent of the sum of the axle weights of the towing vehicle; and (iii) The maximum speed of the portable conveyor and towing vehicle is limited to 45 miles per hour (mph) on two lane roads and 55 mph on freeways. [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996; 70 FR 48049, Aug. 15, 2005; 76 FR 56321, Sept. 13, 2011; 91 FR 7890, Feb. 19, 2026] § 393.43 Breakaway and emergency braking. (a) Towing vehicle protection system. (b) Emergency brake requirements, air brakes. (c) Emergency brake requirements, vacuum brakes. (d) Breakaway braking requirements for trailers. (e) Emergency valves. (f) Exception. [53 FR 49384, Dec. 7, 1988, as amended at 70 FR 48050, Aug. 15, 2005] § 393.44 Front brake lines, protection. On every bus, if equipped with air brakes, the braking system shall be so constructed that in the event any brake line to any of the front wheels is broken, the driver can apply the brakes on the rear wheels despite such breakage. The means used to apply the brakes may be located forward of the driver's seat as long as it can be operated manually by the driver when the driver is properly restrained by any seat belt assembly provided for use. Every bus shall meet this requirement or comply with the regulations in effect at the time of its manufacture. [53 FR 49400, Dec. 7, 1988] § 393.45 Brake tubing and hoses; hose assemblies and end fittings. (a) General construction requirements for tubing and hoses, assemblies, and end fittings. (b) Brake tubing and hose installation. (1) Be long and flexible enough to accommodate without damage all normal motions of the parts to which it is attached; (2) Be secured against chafing, kinking, or other mechanical damage; and (3) Be installed in a manner that prevents it from contacting the vehicle's exhaust system or any other source of high temperatures. (c) Nonmetallic brake tubing. (1) The coiled tubing has a straight segment (pigtail) at each end that is at least 51 mm (2 inches) in length and is encased in a spring guard or similar device which prevents the tubing from kinking at the fitting at which it is attached to the vehicle; and (2) The spring guard or similar device has at least 51 mm (2 inches) of closed coils or similar surface at its interface with the fitting and extends at least 38 mm (1 1/2 (d) Brake tubing and hose connections. [70 FR 48050, Aug. 15, 2005, as amended at 91 FR 45661, July 21, 2026] § 393.46 [Reserved] § 393.47 Brake actuators, slack adjusters, linings/pads and drums/rotors. (a) General requirements. (b) Brake chambers. (c) Slack adjusters. (d) Linings and pads. (1) Steering axle brakes. 3/16 1/4 1/8 1/16 (2) Non-steering axle brakes. 1/4 1/8 1/16 (e) Clamp, Bendix DD-3, bolt-type, and rotochamber brake actuator readjustment limits. Clamp-Type Brake Chambers Type Outside diameter Brake readjustment limit: standard stroke chamber Brake readjustment limit: long stroke chamber 6 4 1 2 1 1 4 9 5 1 4 1 3 8 12 5 11 16 1 3 8 1 3 4 16 6 3 8 1 3 4 2 in. (50.8 mm). 20 6 25 32 1 3 4 2 in. (50.8 mm). 1 2 1 24 7 7 32 1 3 4 2 in. (50.8 mm). 1 2 2 30 8 3 32 2 in. (50.8 mm) 2 1 2 36 9 in. (229 mm) 2 1 2 1 2 Bendix DD-3 Brake Chambers Type Outside diameter Brake readjustment limit 30 8 1 8 2 1 4 Bolt-Type Brake Chambers Type Outside diameter Brake readjustment limit A 6 15 16 1 3 8 B 9 3 16 1 3 4 C 8 1 16 1 3 4 D 5 1 4 1 1 4 E 6 3 16 1 3 8 F 11 in. (279 mm) 2 1 4 G 9 7 8 2 in. (50.8 mm). Rotochamber-Type Brake Chambers Type Outside diameter Brake readjustment limit 9 4 9 32 1 1 2 12 4 13 16 1 1 2 16 5 13 32 2 in. (50.8 mm). 20 5 15 16 2 in. (50.8 mm). 24 6 13 32 2 in. (50.8 mm). 30 7 1 16 2 1 4 36 7 5 8 2 3 4 50 8 7 8 3 in. (76.2 mm). (2) For actuator types not listed in these tables, the pushrod stroke must not be greater than 80 percent of the rated stroke marked on the actuator by the actuator manufacturer, or greater than the readjustment limit marked on the actuator by the actuator manufacturer. (f) Wedge brake adjustment. 1/16 (g) Drums and rotors. [70 FR 48051, Aug. 15, 2005, as amended at 77 FR 46638, Aug. 6, 2012; 86 FR 57076, Oct. 14, 2021] § 393.48 Brakes to be operative. (a) General rule. (b) Devices to reduce or remove front-wheel braking effort. (1) Manually operated devices. (2) Automatic devices. (c) Exception. (1) A towed vehicle with disabling damage as defined in § 390.5; (2) A vehicle which is towed in a driveaway-towaway operation and is included in the exemption to the requirement for brakes on all wheels, § 393.42(b); (3) Unladen converter dollies with a gross weight of 1,361 kg (3,000 lbs) or less, and manufactured prior to March 1, 1998; (4) The steering axle of a three-axle dolly which is steered by a co-driver; (5) Loaded house moving dollies, specialized trailers and dollies used to transport industrial furnaces, reactors, and similar motor vehicles provided the speed at which the combination of vehicles will be operated does not exceed 32 km/hour (20 mph) and brakes on the combination of vehicles are capable of stopping the combination within 12.2 meters (40 feet) from the speed at which the vehicle is being operated or 32 km/hour (20 mph), whichever is less. (6) Raised lift axles. Brakes on lift axles need not be capable of being operated while the lift axle is raised. However, brakes on lift axles must be capable of being applied whenever the lift axle is lowered and the tires contact the roadway. (d) Surge brakes. (i) Any trailer with a gross vehicle weight rating (GVWR) of 12,000 pounds or less, when its GVWR does not exceed 1.75 times the GVWR of the towing vehicle; and (ii) Any trailer with a GVWR greater than 12,000 pounds, but less than 20,001 pounds, when its GVWR does not exceed 1.25 times the GVWR of the towing vehicle. (2) The gross vehicle weight (GVW) of a trailer equipped with surge brakes may be used instead of its GVWR to calculate compliance with the weight ratios specified in paragraph (d)(1) of this section when the trailer manufacturer's GVWR label is missing. (3) The GVW of a trailer equipped with surge brakes must be used to calculate compliance with the weight ratios specified in paragraph (d)(1) of this section when the trailer's GVW exceeds its GVWR. (4) The surge brakes must meet the requirements of § 393.40. [70 FR 48051, Aug. 15, 2005, as amended at 72 FR 9870, Mar. 6, 2007] § 393.49 Control valves for brakes. (a) General rule. (b) Driveaway-Towaway Exception. (c) Surge brake exception. [72 FR 9871, Mar. 6, 2007, as amended at 78 FR 58484, Sept. 24, 2013] § 393.50 Reservoirs required. (a) Reservoir capacity for air-braked power units manufactured on or after March 1, 1975, and air-braked trailers manufactured on or after January 1, 1975. (b) Reservoir capacity for air-braked vehicles not subject to FMVSS No. 121 on the date of manufacture and all vacuum braked vehicles. (c) Safeguarding of air and vacuum. (d) Drain valves for air braked vehicles. [70 FR 48052, Aug. 15, 2005] § 393.51 Warning signals, air pressure and vacuum gauges. (a) General Rule. (b) Hydraulic brakes. (c) Air brakes. (1) A pressure gauge, visible to a person seated in the normal driving position, which indicates the air pressure (in kilopascals (kPa) or pounds per square inch (psi)) available for braking; and (2) A warning signal that is audible or visible to a person in the normal driving position and provides a continuous warning to the driver whenever the air pressure in the service reservoir system is at 379 kPa (55 psi) and below, or one-half of the compressor governor cutout pressure, whichever is less. (d) Vacuum brakes. (1) A vacuum gauge, visible to a person seated in the normal driving position, which indicates the vacuum (in millimeters or inches of mercury) available for braking; and (2) A warning signal that is audible or visible to a person in the normal driving position and provides a continuous warning to the driver whenever the vacuum in the vehicle's supply reservoir is less than 203 mm (8 inches) of mercury. (e) Hydraulic brakes applied or assisted by air or vacuum. (f) Exceptions. [70 FR 48052, Aug. 15, 2005] § 393.52 Brake performance. (a) Upon application of its service brakes, a motor vehicle or combination of motor vehicles must under any condition of loading in which it is found on a public highway, be capable of— (1) Developing a braking force at least equal to the percentage of its gross weight specified in the table in paragraph (d) of this section; (2) Decelerating to a stop from 20 miles per hour at not less than the rate specified in the table in paragraph (d) of this section; and (3) Stopping from 20 miles per hour in a distance, measured from the point at which movement of the service brake pedal or control begins, that is not greater than the distance specified in the table in paragraph (d) of this section; or, for motor vehicles or motor vehicle combinations that have a GVWR or GVW greater than 4,536 kg (10,000 pounds), (4) Developing only the braking force specified in paragraph (a)(1) of this section and the stopping distance specified in paragraph (a)(3) of this section, if braking force is measured by a performance-based brake tester which meets the requirements of functional specifications for performance-based brake testers for commercial motor vehicles, where braking force is the sum of the braking force at each wheel of the vehicle or vehicle combination as a percentage of gross vehicle or combination weight. (b) Upon application of its emergency brake system and with no other brake system applied, a motor vehicle or combination of motor vehicles must, under any condition of loading in which it is found on a public highway, be capable of stopping from 20 miles per hour in a distance, measured from the point at which movement of the emergency brake control begins, that is not greater than the distance specified in the table in paragraph (d) of this section. (c) Conformity to the stopping-distance requirements of paragraphs (a) and (b) of this section shall be determined under the following conditions: (1) Any test must be made with the vehicle on a hard surface that is substantially level, dry, smooth, and free of loose material. (2) The vehicle must be in the center of a 12-foot-wide lane when the test begins and must not deviate from that lane during the test. (d) Vehicle brake performance table: Type of motor vehicle Service brake systems Emergency brake systems Braking force as a percentage of gross vehicle or combination weight Deceleration in feet per second per second Application and braking distance in feet from initial speed at 20 mph Application and braking distance in feet from initial speed of 20 mph A. Passenger-carrying vehicles: (1) Vehicles with a seating capacity of 10 persons or less, including driver, and built on a passenger car chassis 65.2 21 20 54 (2) Vehicles with a seating capacity of more than 10 persons, including driver, and built on a passenger car chassis; vehicles built on a truck or bus chassis and having a manufacturer's GVWR of 10,000 pounds or less 52.8 17 25 66 (3) All other passenger-carrying vehicles 43.5 14 35 85 B. Property-carrying vehicles: (1) Single unit vehicles having a manufacturer's GVWR of 10,000 pounds or less 52.8 17 25 66 (2) Single unit vehicles having a manufacturer's GVWR of more than 10,000 pounds, except truck tractors. Combinations of a 2-axle towing vehicle and trailer having a GVWR of 3,000 pounds or less. All combinations of 2 or less vehicles in drive-away or tow-away operation 43.5 14 35 85 (3) All other property-carrying vehicles and combinations of property-carrying vehicles 43.5 14 40 90 Notes: (a) There is a definite mathematical relationship between the figures in columns 2 and 3. If the decelerations set forth in column 3 are divided by 32.2 feet per-second per-second, the figures in column 2 will be obtained. (For example, 21 divided by 32.2 equals 65.2 percent.) Column 2 is included in the tabulation because certain brake testing devices utilize this factor. (b) The decelerations specified in column 3 are an indication of the effectiveness of the basic brakes, and as measured in practical brake testing are the maximum decelerations attained at some time during the stop. These decelerations as measured in brake tests cannot be used to compute the values in column 4 because the deceleration is not sustained at the same rate over the entire period of the stop. The deceleration increases from zero to a maximum during a period of brake system application and brake-force buildup. Also, other factors may cause the deceleration to decrease after reaching a maximum. The added distance that results because maximum deceleration is not sustained is included in the figures in column 4 but is not indicated by the usual brake-testing devices for checking deceleration. (c) The distances in column 4 and the decelerations in column 3 are not directly related. “Brake-system application and braking distance in feet” (column 4) is a definite measure of the overall effectiveness of the braking system, being the distance traveled between the point at which the driver starts to move the braking controls and the point at which the vehicle comes to rest. It includes distance traveled while the brakes are being applied and distance traveled while the brakes are retarding the vehicle. (d) The distance traveled during the period of brake-system application and brake-force buildup varies with vehicle type, being negligible for many passenger cars and greatest for combinations of commercial vehicles. This fact accounts for the variation from 20 to 40 feet in the values in column 4 for the various classes of vehicles. (e) The terms “GVWR” and “GVW” refer to the manufacturer's gross vehicle weight rating and the actual gross vehicle weight, respectively. [36 FR 20298, Oct. 20, 1971, as amended at 37 FR 5251, Mar. 11, 1972; 37 FR 11336, June 7, 1972; 67 FR 51777, Aug. 9, 2002] § 393.53 Automatic brake adjusters and brake adjustment indicators. (a) Automatic brake adjusters (hydraulic brake systems). (b) Automatic brake adjusters (air brake systems). (c) Brake adjustment indicator (air brake systems). [60 FR 46245, Sept. 6, 1995, as amended at 77 FR 46639, Aug. 6, 2012] § 393.55 Antilock brake systems. (a) Hydraulic brake systems. (b) ABS malfunction indicators for hydraulic braked vehicles. (c) Air brake systems. (2) Each air braked commercial motor vehicle other than a truck tractor, manufactured on or after March 1, 1998 (except commercial motor vehicles engaged in driveaway-towaway operations), shall be equipped with an antilock brake system that meets the requirements of FMVSS No. 121 (49 CFR 571.121, S5.1.6.1(a) for trucks and buses, S5.2.3 for semitrailers, converter dollies and full trailers). (d) ABS malfunction circuits and signals for air braked vehicles. (2) Each truck tractor manufactured on or after March 1, 2001, and each single-unit vehicle that is equipped to tow another air-braked vehicle, subject to the requirements of paragraph (c) of this section, shall be equipped with an electrical circuit that is capable of transmitting a malfunction signal from the antilock brake system(s) on the towed vehicle(s) to the trailer ABS malfunction lamp in the cab of the towing vehicle, and shall have the means for connection of the electrical circuit to the towed vehicle. The ABS malfunction circuit and signal shall meet the requirements of FMVSS No. 121 (49 CFR 571.121, S5.1.6.2(b)). (3) Each semitrailer, trailer converter dolly, and full trailer manufactured on or after March 1, 2001, and subject to the requirements of paragraph (c)(2) of this section, shall be equipped with an electrical circuit that is capable of signaling a malfunction in the trailer's antilock brake system, and shall have the means for connection of this ABS malfunction circuit to the towing vehicle. In addition, each trailer manufactured on or after March 1, 2001, subject to the requirements of paragraph (c)(2) of this section, that is designed to tow another air-brake equipped trailer shall be capable of transmitting a malfunction signal from the antilock brake system(s) of the trailer(s) it tows to the vehicle in front of the trailer. The ABS malfunction circuit and signal shall meet the requirements of FMVSS No. 121 (49 CFR 571.121, S5.2.3.2). (e) Exterior ABS malfunction indicator lamps for trailers. [63 FR 24465, May 4, 1998, as amended at 75 FR 57396, Sept. 21, 2010] Subpart D—Glazing and Window Construction § 393.60 Glazing in specified openings. (a) Glazing material. (b) Windshields required. (c) Windshield condition. Exceptions: (1) Coloring or tinting which meets the requirements of paragraph (d) of this section; (2) Any crack that is not intersected by any other cracks; (3) Any damaged area which can be covered by a disc 19 mm ( 3/4 (d) Coloring or tinting of windshields and windows. (e) Prohibition on obstructions to the driver's field of view—(1) Devices mounted on the interior of the windshield. (ii) Paragraph (e)(1)(i) of this section does not apply to vehicle safety technologies, (A) Not more than 216 mm (8.5 inches) below the upper edge of the area swept by the windshield wipers; (B) Not more than 175 mm (7 inches) above the lower edge of the area swept by the windshield wipers; and (C) Outside the driver's sight lines to the road and highway signs and signals. (2) Decals and stickers mounted on the windshield. 1/2 [63 FR 1387, Jan. 9, 1998, as amended at 81 FR 65574, Sept. 23, 2016; 83 FR 22878, May 17, 2018; 87 FR 12604, Mar. 7, 2022] § 393.61 Truck and truck tractor window construction. Each truck and truck tractor (except trucks engaged in armored car service) shall have at least one window on each side of the driver's compartment. Each window must have a minimum area of 1,290 cm 2 2 3/4 [70 FR 48052, Aug. 15, 2005] § 393.62 Emergency exits for buses. (a) Buses manufactured on or after September 1, 1994. (b) Buses manufactured on or after September 1, 1973, but before September 1, 1994. (2) Each bus (including a school bus used in interstate commerce for non-school bus operations) with a GVWR of 4,536 kg (10,000 lbs) or less must meet the requirements of FMVSS No. 217, S5.2.2.3 in effect on the date of manufacture. (c) Buses manufactured before September 1, 1973. 2 2 2 2 3/4 (d) Laminated safety glass/push-out window requirements for buses manufactured before September 1, 1973. (1) Safety glass. (2) Push-out windows. (e) Emergency exit identification. (f) Exception for the transportation of prisoners. [70 FR 48052, Aug. 15, 2005] § 393.63 [Reserved] Subpart E—Fuel Systems § 393.65 All fuel systems. (a) Application of the rules in this section. (b) Location. (1) No part of the system extends beyond the widest part of the vehicle; (2) No part of a fuel tank is forward of the front axle of a power unit; (3) Fuel spilled vertically from a fuel tank while it is being filled will not contact any part of the exhaust or electrical systems of the vehicle, except the fuel level indicator assembly; (4) Fill pipe openings are located outside the vehicle's passenger compartment and its cargo compartment; (5) A fuel line does not extend between a towed vehicle and the vehicle that is towing it while the combination of vehicles is in motion; and (6) No part of the fuel system of a bus manufactured on or after January 1, 1973, is located within or above the passenger compartment. (c) Fuel tank installation. (d) Gravity or syphon feed prohibited. (1) When an auxiliary pump with a nominal fuel tank capacity of not more than five gallons is mounted on the trailer chassis frame or trailer bed for purposes other than operation of the motor vehicle; and (2) The auxiliary pump shall be operated only when the motor vehicle is not in motion. (e) Selection control valve location. (1) The driver may operate it while watching the roadway and without leaving his/her driving position; or (2) The driver must stop the vehicle and leave his/her seat in order to operate the valve. (f) Fuel lines. (1) Long enough and flexible enough to accommodate normal movements of the parts to which it is attached without incurring damage; and (2) Secured against chafing, kinking, or other causes of mechanical damage. (g) Excess flow valve. [36 FR 15445, Aug. 14, 1971, as amended at 37 FR 4341, Mar. 2, 1972; 37 FR 28752, Dec. 29, 1972; 91 FR 7893, Feb. 19, 2026] § 393.67 Liquid fuel tanks. (a) Application of the rules in this section. (1) A liquid fuel tank manufactured on or after January 1, 1973, and a side-mounted gasoline tank must conform to all rules in this section. (2) A diesel fuel tank manufactured before January 1, 1973, and mounted on a bus must conform to the rules in paragraphs (c)(7)(ii) and (d)(2) of this section. (3) A diesel fuel tank manufactured before January 1, 1973, and mounted on a vehicle other than a bus must conform to the rules in paragraph (c)(7)(ii) of this section. (4) A gasoline tank, other than a side-mounted gasoline tank, manufactured before January 1, 1973, and mounted on a bus must conform to the rules in paragraphs (c) (1) through (10) and (d)(2) of this section. (5) A gasoline tank, other than a side-mounted gasoline tank, manufactured before January 1, 1973, and mounted on a vehicle other than a bus must conform to the rules in paragraphs (c) (1) through (10), inclusive, of this section. (6) Private motor carrier of passengers. Motor carriers engaged in the private transportation of passengers may continue to operate a commercial motor vehicle which was not subject to this section or 49 CFR 571.301 at the time of its manufacture, provided the fuel tank of such vehicle is maintained to the original manufacturer's standards. (7) Motor vehicles that meet the fuel system integrity requirements of 49 CFR 571.301 are exempt from the requirements of this subpart, as they apply to the vehicle's fueling system. (b) Definitions. (1) The term liquid fuel tank (2) A side-mounted (i) If mounted on a truck tractor, extends outboard of the vehicle frame and outside of the plan view outline of the cab; or (ii) If mounted on a truck, extends outboard of a line parallel to the longitudinal centerline of the truck and tangent to the outboard side of a front tire in a straight ahead position. In determining whether a fuel tank on a truck or truck tractor is side-mounted, the fill pipe is not considered a part of the tank. (c) Construction of liquid fuel tanks Joints. (2) Fittings. (3) Threads. (4) Drains and bottom fittings. (ii) Drains or other bottom fittings must be protected against damage from impact. (iii) If a fuel tank has drains the drain fittings must permit substantially complete drainage of the tank. (iv) Drains or other bottom fittings must be installed in a flange or spud designed to accommodate it. (5) Fuel withdrawal fittings. (6) [Reserved] (7) Fill pipe. (ii) For diesel-fueled vehicles, the fill pipe and vents of a fuel tank having a capacity of more than 94.75 L (25 gallons) of fuel must permit filling the tank with fuel at a rate of at least 75.8 L/m (20 gallons per minute) without fuel spillage. (iii) For gasoline- and methanol-fueled vehicles with a GVWR of 3,744 kg (8,500 pounds) or less, the vehicle must permit filling the tank with fuel dispensed at the applicable fill rate required by the regulations of the Environmental Protection Agency under 40 CFR 80.22. (iv) For gasoline- and methanol-fueled vehicles with a GVWR of 14,000 pounds (6,400 kg) or less, the vehicle must comply with the applicable fuel-spitback prevention and onboard refueling vapor recovery regulations of the Environmental Protection Agency under 40 CFR part 86. (v) Each fill pipe must be fitted with a cap that can be fastened securely over the opening in the fill pipe. Screw threads or a bayonet-type point are methods of conforming to the requirements of paragraph (c) of this section. (8) Safety venting system. (9) Pressure resistance. (10) Air vent. (11) Markings. (12) Overfill restriction. (d) Liquid fuel tank tests. (1) Safety venting system test Procedure. (ii) Required performance. (2) Leakage test Procedure. (ii) Required performance. (e) Side-mounted liquid fuel tank tests. (1) Drop test Procedure. (ii) Required performance. (2) Fill-pipe test Procedure. (ii) Required performance. (f) Certification and markings. (1) The month and year of manufacture, (2) The manufacturer's name on tanks manufactured on and after July 1, 1989, and means of identifying the facility at which the tank was manufactured, and (3) A certificate that it conforms to the rules in this section applicable to the tank. The certificate must be in the form set forth in either of the following: (i) If a tank conforms to all rules in this section pertaining to side-mounted fuel tanks: “Meets all FMCSA side-mounted tank requirements.” (ii) If a tank conforms to all rules in this section pertaining to tanks which are not side-mounted fuel tanks: “Meets all FMCSA requirements for non-side-mounted fuel tanks.” (iii) The form of certificate specified in paragraph (f)(3) (i) or (ii) of this section may be used on a liquid fuel tank manufactured before July 11, 1973, but it is not mandatory for liquid fuel tanks manufactured before March 7, 1989. The form of certification manufactured on or before March 7, 1989, must meet the requirements in effect at the time of manufacture. (4) Exception. not (i) Ford vehicles with GVWR over 10,000 pounds identified as follows: The vehicle identification numbers (VINs) contain A, K, L, M, N, W, or X in the fourth position. (ii) GM G-Vans (Chevrolet Express and GMC Savanna) and full-sized C/K trucks (Chevrolet Silverado and GMC Sierra) with GVWR over 10,000 pounds identified as follows: The VINs contain either a “J” or a “K” in the fourth position. In addition, the seventh position of the VINs on the G-Van will contain a “1.” [36 FR 15445, Aug. 14, 1971, as amended at 37 FR 4341, Mar. 2, 1972; 37 FR 28753, Dec. 29, 1972; 45 FR 46424, July 10, 1980; 53 FR 49400, Dec. 7, 1988; 59 FR 8753, Feb. 23, 1994; 69 FR 31305, June 3, 2004; 70 FR 48053, Aug. 15, 2005; 78 FR 58484, Sept. 24, 2013; 91 FR 7884, Feb. 19, 2026] § 393.68 Compressed natural gas fuel containers. (a) Applicability. (b) CNG containers manufactured on or after March 26, 1995. (c) Labeling. [70 FR 48053, Aug. 15, 2005] § 393.69 Liquefied petroleum gas systems. (a) A fuel system that uses liquefied petroleum gas as a fuel for the operation of a motor vehicle or for the operation of auxiliary equipment installed on, or used in connection with, a motor vehicle must conform to the “Standards for the Storage and Handling of Liquefied Petroleum Gases” of the National Fire Protection Association, Battery March Park, Quincy, MA 02269, as follows: (1) A fuel system installed before December 31, 1962, must conform to the 1951 edition of the Standards. (2) A fuel system installed on or after December 31, 1962, and before January 1, 1973, must conform to Division IV of the June 1959 edition of the Standards. (3) A fuel system installed on or after January 1, 1973, and providing fuel for propulsion of the motor vehicle must conform to Division IV of the 1969 edition of the Standards. (4) A fuel system installed on or after January 1, 1973, and providing fuel for the operation of auxiliary equipment must conform to Division VII of the 1969 edition of the Standards. (b) When the rules in this section require a fuel system to conform to a specific edition of the Standards, the fuel system may conform to the applicable provisions in a later edition of the Standards specified in this section. (c) The tank of a fuel system must be marked to indicate that the system conforms to the Standards. [36 FR 15445, Aug. 14, 1971, as amended at 37 FR 4342, Mar. 2, 1972; 41 FR 53031, Dec. 3, 1976; 53 FR 49400, Dec. 7, 1988] Subpart F—Coupling Devices and Towing Methods § 393.70 Coupling devices and towing methods, except for driveaway-towaway operations. (a) Tracking. (b) Fifth wheel assemblies Mounting Lower half. (ii) Upper half. (2) Locking. (3) Location. (c) Towing of full trailers. (1) Be structurally adequate for the weight being drawn; (2) Be properly and securely mounted; (3) Provide for adequate articulation at the connection without excessive slack at that location; and (4) Be provided with a locking device that prevents accidental separation of the towed and towing vehicles. The mounting of the trailer hitch (pintle hook or equivalent mechanism) on the towing vehicle must include reinforcement or bracing of the frame sufficient to produce strength and rigidity of the frame to prevent its undue distortion. (d) Safety devices in case of tow-bar failure or disconnection. (1) The safety device must not be attached to the pintle hook or any other device on the towing vehicle to which the tow-bar is attached. However, if the pintle hook or other device was manufactured prior to July 1, 1973, the safety device may be attached to the towing vehicle at a place on a pintle hook forging or casting if that place is independent of the pintle hook. (2) The safety device must have no more slack than is necessary to permit the vehicles to be turned properly. (3) The safety device, and the means of attaching it to the vehicles, must have an ultimate strength of not less than the gross weight of the vehicle or vehicles being towed. (4) The safety device must be connected to the towed and towing vehicles and to the tow-bar in a manner which prevents the tow-bar from dropping to the ground in the event it fails or becomes disconnected. (5) Except as provided in paragraph (d)(6) of this section, if the safety device consists of safety chains or cables, the towed vehicle must be equipped with either two safety chains or cables or with a bridle arrangement of a single chain or cable attached to its frame or axle at two points as far apart as the configuration of the frame or axle permits. The safety chains or cables shall be either two separate pieces, each equipped with a hook or other means for attachment to the towing vehicle, or a single piece leading along each side of the tow-bar from the two points of attachment on the towed vehicle and arranged into a bridle with a single means of attachment to be connected to the towing vehicle. When a single length of cable is used, a thimble and twin-base cable clamps shall be used to form the forward bridle eye. The hook or other means of attachment to the towing vehicle shall be secured to the chains or cables in a fixed position. (6) If the towed vehicle is a converter dolly with a solid tongue and without a hinged tow-bar or other swivel between the fifth wheel mounting and the attachment point of the tongue eye or other hitch device— (i) Safety chains or cables, when used as the safety device for that vehicle, may consist of either two chains or cables or a single chain or cable used alone; (ii) A single safety device, including a single chain or cable used alone as the safety device, must be in line with the centerline of the trailer tongue; and (iii) The device may be attached to the converter dolly at any point to the rear of the attachment point of the tongue eye or other hitch device. (7) Safety devices other than safety chains or cables must provide strength, security of attachment, and directional stability equal to, or greater than, safety chains or cables installed in accordance with paragraphs (d) (5) and (6) of this section. (8)(i) When two safety devices, including two safety chains or cables, are used and are attached to the towing vehicle at separate points, the points of attachment on the towing vehicle shall be located equally distant from, and on opposite sides of, the longitudinal centerline of the towing vehicle. (ii) Where two chains or cables are attached to the same point on the towing vehicle, and where a bridle or a single chain or cable is used, the point of attachment must be on the longitudinal centerline or within 152 mm (6 inches) to the right of the longitudinal centerline of the towing vehicle. (iii) A single safety device, other than a chain or cable, must also be attached to the towing vehicle at a point on the longitudinal centerline or within 152 mm (6 inches) to the right of the longitudinal centerline of the towing vehicle. [37 FR 21439, Oct. 11, 1972, as amended at 70 FR 48053, Aug. 15, 2005] § 393.71 Coupling devices and towing methods, driveaway-towaway operations. (a) Number in combination. (2) No more than one tow-bar or ball-and-socket type coupling device may be used in any combination. (3) When motor vehicles are towed by means of triple saddle-mounts, all but the final towed vehicle must have brakes acting on all wheels in contact with the roadway. (b) Carrying vehicles on towing vehicle. (2) No motor vehicle or motor vehicles may be full-mounted on a towing vehicle unless the relationship of such full-mounted vehicles to the rear axle or axles results in proper distribution of the total gross weight of the vehicles and does not unduly interfere with the steering, braking, or maneuvering of the towing vehicle, or otherwise contribute to the unsafe operation of the vehicles comprising the combination. (3) Saddle-mounted vehicles must be arranged such that the gross weight of the vehicles is properly distributed to prevent undue interference with the steering, braking, or maneuvering of the combination of vehicles. (c) Carrying vehicles on towed vehicles. (2) No motor vehicle shall be full-mounted on a motor vehicle towed by means of a tow-bar unless the towed vehicle is equipped with brakes and is provided with means for effective application of brakes acting on all wheels and is towed on its own wheels. (3) No motor vehicle or motor vehicles shall be full-mounted on a motor vehicle towed by means of a saddle-mount unless the center line of the kingpin or equivalent means of attachment of such towed vehicle shall be so located on the towing vehicle that the relationship to the rear axle or axles results in proper distribution of the total gross weight of the vehicles and does not unduly interfere with the steering, braking, or maneuvering of the towing vehicle or otherwise contribute to the unsafe operation of vehicles comprising the combination; and unless a perpendicular to the ground from the center of gravity of the full-mounted vehicles lies forward of the center line of the rear axle of the saddle-mounted vehicle. (4) If a motor vehicle towed by means of a saddle-mount has any vehicle full-mounted on it, the saddle-mounted vehicle must at all times while so loaded have effective brakes acting on all wheels in contact with the roadway. (d) Bumper tow-bars on heavy vehicles prohibited. (e) Front wheels of saddle-mounted vehicles restrained. (f) Vehicles to be towed in forward position. (g) Means required for towing. (h) Requirements for tow-bars. (1) Tow-bars, structural adequacy and mounting. Gross weight of towed vehicle (pounds) 1 Longitudinal strength in tension and compression 2 All tow-bars New tow-bars acquired and used by a motor carrier after Sept. 30, 1948 Strength as a beam (in any direction concentrated load at center) 2 3 Pounds Less than 5,000 3,000 6,500 3,000 5,000 and over Less than 10,000 6,000 ( 1 ( 1 10,000 and over Less than 15,000 9,000 ( 1 ( 1 1 2 3 (2) Tow-bars, jointed. (3) Tow-bar fastenings. Provided, however, (4) Means of adjusting length. (5) Method of clamping. (6) Tow-bar connection to steering mechanism. (7) Tracking. (8) Passenger car-trailer type couplings. 1 1 (9) Marking tow-bars. This tow-bar complies with the requirements of the Federal Motor Carrier Safety Administration for (maximum gross weight for which tow-bar is manufactured) vehicles. Allowable Maximum Gross Weight Manufactured (month and year) by (name of manufacturer) Tow-bar certification manufactured before the effective date of this regulation must meet requirements in effect at the time of manufacture. (10) Safety devices in case of tow-bar failure or disconnection. (ii) If chains or cables are used as the safety device, they shall be crossed and attached to the vehicles near the points of bumper attachments to the chassis of the vehicles. The length of chain used shall be no more than necessary to permit free turning of the vehicles. The chains shall be attached to the tow-bar at the point of crossing or as close to that point as is practicable. (iii) A safety device other than safety chains or cables must provide strength, security of attachment, and directional stability equal to, or greater than, that provided by safety chains or cables installed in accordance with paragraph (h)(10)(ii) of this section. A safety device other than safety chains or cables must be designed, constructed, and installed so that, if the tow-bar fails or becomes disconnected, the tow-bar will not drop to the ground. (i) [Reserved] (j) Requirements for upper-half of saddle-mounts. (1) Upper-half connection to towed vehicle. (2) U- bolts or other attachments. Provided, however, Diameter of U-Bolts in Inches Weight in pounds of heaviest towed vehicle Double or triple saddle-mount Front mount Middle or front mount Rear mount Single saddle-mount 1 Up to 5,000 0.625 0.5625 0.500 0.500 5,000 and over 0.6875 0.625 0.5625 0.5625 1 (3) U- bolts and points of support, location. (4) Cradle-type upper-halves, specifications. (5) Lateral movement of towed vehicle. 3/16 (ii) Towed vehicles with an axle with a drop of 3 inches or more, or connected by a saddle-mount constructed in accordance with paragraph (m)(2) of this section, need not be restrained by chains or cables provided that the upper-half is so designed as to provide against such relative motion. (iii) Chains or cables shall not be required if the upper-half is so designed as positively to provide against lateral movement of the axle. (k) Requirements for lower half of saddle-mounts. (1) U- bolts or other attachments. Provided, however, Total Cross-Sectional Area of U-Bolts in Square Inches Weight in pounds of heaviest towed vehicle Double or triple saddle-mount Front mount Middle or front mount Rear mount Single saddle-mount 1 Up to 5,000 1.2 1.0 0.8 0.8 5,000 and over 1.4 1.2 1.0 1.0 1 (2) Shifting. (3) Swaying. (ii) The lower-half shall have a bearing surface on the frame of the towing vehicle of such dimensions that the pressure exerted by the lower-half upon the frame of the towing vehicle shall not exceed 200 pounds per square inch under any conditions of static loading. Hardwood blocks or blocks of other suitable material, such as hard rubber, aluminum or brakelining, if used between the lower half and the frame of the towing vehicle shall be at least 1/2 (iii) Under no condition shall the highest point of support of the towed vehicle by the upper-half be more than 24 inches, measured vertically, above the top of the frame of the towing vehicle, measured at the point where the lower-half rests on the towing vehicle. (4) Wood blocks. (ii) Hardwood blocks must be at least 4 inches in width and the surfaces between blocks or block and lower-half or block and upper-half shall be planed and so installed and maintained as to minimize any tendency of the towed vehicle to sway or rock. (5) Cross-member, general requirements. (6) Cross-member, use of wood. (7) Lower half strength. Minimum Test Load in Pounds Weight in pounds of heaviest towed vehicle Double or triple saddle-mount Front mount Middle or front mount Rear mount Single saddle-mount 1 Up to 5,000 15,000 10,000 5,000 5,000 5,000 and over 30,000 20,000 10,000 10,000 1 (l) Requirements for kingpins of saddle-mounts. (1) Kingpin size. Diameter of Solid Kingpin in Inches Weight in pounds of heaviest towed vehicle Double or triple saddle-mount Front mount Middle or front mount Rear mount Single saddle-mount 1 Mild steel H.T.S. 2 Mild steel H.T.S. 2 Mild steel H.T.S. 2 Mild steel H.T.S. Up to 5,000 1.125 1.000 1.000 0.875 0.875 0.750 0.875 0.750 5,000 and over 1.500 1.125 1.250 1.000 1.000 0.875 1.000 0.875 1 2 (ii) If a ball and socket joint is used in place of a kingpin, the diameter of the neck of the ball shall be at least equal to the diameter of the corresponding solid kingpin given in the above table. If hollow kingpins are used, the metallic cross-sectional area shall be at least equal to the cross-sectional area of the corresponding solid kingpin. (2) Kingpin fit. (3) Kingpin bushing on saddle-mounts. (4) Kingpin to restrain vertical motion. (m) Additional requirements for saddle-mounts. (1) Bearing surface between upper and lower-halves. Provided, however, And further provided, (2) Saddle-mounts, angularity. (3) Tracking. (4) Prevention of frame bending. (5) Extension of frame. (6) Nuts, secured. (7) Inspection of all parts. (8) Saddle-mounts, marking. This saddle-mount complies with the requirements of the Federal Motor Carrier Safety Administration for vehicles up to 5,000 pounds (or over 5,000 pounds): Manufactured (Month and year) by (Name of manufacturer) (n) Requirements for devices used to connect motor vehicles or parts of motor vehicles together to form one vehicle Front axle attachment. (2) Rear axle attachment. 1/2 1/2 3/4 [33 FR 19735, Dec. 25, 1968, as amended at 35 FR 10907, July 7, 1970; 37 FR 21440, Oct. 11, 1972; 53 FR 49400, Dec. 7, 1988; 70 FR 48054, Aug. 15, 2005; 76 FR 56322, Sept. 13, 2011; 78 FR 58484, Sept. 24, 2013; 80 FR 59075, Oct. 1, 2015; 86 FR 57076, Oct. 14, 2021] Subpart G—Miscellaneous Parts and Accessories § 393.75 Tires. (a) No motor vehicle shall be operated on any tire that— (1) Has body ply or belt material exposed through the tread or sidewall, (2) Has any tread or sidewall separation, (3) Is flat or has an audible leak, or (4) Has a cut to the extent that the ply or belt material is exposed. (b) Any tire on the front wheels of a bus, truck, or truck tractor shall have a tread groove pattern depth of at least 4/32 (c) Except as provided in paragraph (b) of this section, tires shall have a tread groove pattern depth of at least 2/32 (d) No bus shall be operated with regrooved, recapped or retreaded tires on the front wheels. (e) A regrooved tire with a load-carrying capacity equal to or greater than 2,232 kg (4,920 pounds) shall not be used on the front wheels of any truck or truck tractor. (f) No motor vehicle may be operated with speed-restricted tires labeled with a maximum speed of 55 mph or less in accordance with S6.5(e) of FMVSS No. 119 at speeds that exceed the rated limit of the tire. (g) Tire loading restrictions (except on manufactured homes). (1) The vehicle is being operated under the terms of a special permit issued by the State; and (2) The vehicle is being operated at a reduced speed to compensate for the tire loading in excess of the manufacturer's rated capacity for the tire. In no case shall the speed exceed 80 km/hr (50 mph). (h)(1) Tire loading restrictions for manufactured homes built before January 1, 2002. (2) Tire loading restrictions for manufactured homes built on or after January 1, 2002. (i) Tire inflation pressure. (2) If the inflation pressure of the tire has been increased by heat because of the recent operation of the vehicle, the cold inflation pressure shall be estimated by subtracting the inflation buildup factor shown in Table 1 from the measured inflation pressure. (j) The requirements in paragraphs (g) and (h) of this section shall not be construed to require manufacturers to add any markings to the sidewall of a tire. Table 1—Inflation Pressure Measurement Correction for Heat Average speed of vehicle Minimum inflation pressure buildup Tires with 1,814 kg (4,000 lbs.) maximum load rating or less Tires with over 1,814 kg (4,000 lbs.) load rating 66-88.5 km/hr (41-55 mph) 34.5 kPa (5 psi) 103.4 kPa (15 psi). [34 FR 9344, June 13, 1969, as amended at 40 FR 44557, Sept. 29, 1975; 41 FR 36657, Aug. 31, 1976; 44 FR 25455, May 1, 1979; 44 FR 47938, Aug. 16, 1979; 53 FR 18057, May 19, 1988; 53 FR 49401, Dec. 7, 1988; 63 FR 8339, Feb. 18, 1998; 65 FR 70220, Nov. 21, 2000; 66 FR 67694, Dec. 31, 2001; 70 FR 48054, Aug. 15, 2005; 81 FR 47731, July 22, 2016; 91 FR 7887, Feb. 19, 2026] § 393.76 Sleeper berths. (a) Dimensions Size. Date of installation on motor vehicle Length measured on centerline of longitudinal axis (inches) Width measured on centerline of transverse axis (inches) Height measured from highest point of top of mattress (inches) 1 Before January 1, 1953 72 18 18 After December 31, 1952, and before October 1, 1975 75 21 21 After September 30, 1975 75 24 24 1 (2) Shape. 1/2 (3) Access. (b) Location. (2) A sleeper berth located within the cargo space of a motor vehicle must be securely compartmentalized from the remainder of the cargo space. A sleeper berth installed on or after January 1, 1953 must be located in the cab or immediately adjacent to the cab and must be securely fixed with relation to the cab. (c) Exit from the berth. (2) A sleeper berth installed before January 1, 1953 must either: (i) Conform to the requirements of paragraph (c)(1) of this section; or (ii) Have at least two exits, each of which is at least 18 inches high and 21 inches wide, located at opposite ends of the vehicle and useable by the occupant without the assistance of any other person. (d) Communication with the driver. (e) Equipment. (1) Adequate bedclothing and blankets; and (2) Either: (i) Springs and a mattress; or (ii) An innerspring mattress; or (iii) A cellular rubber or flexible foam mattress at least four inches thick; or (iv) A mattress filled with a fluid and of sufficient thickness when filled to prevent “bottoming-out” when occupied while the vehicle is in motion. (f) Ventilation. (g) Protection against exhaust and fuel leaks and exhaust heat. (h) Occupant restraint. [39 FR 14711, Apr. 26, 1974; 39 FR 17233, May 14, 1974, as amended at 53 FR 49401, Dec. 7, 1988] § 393.77 Heaters. On every motor vehicle, every heater shall comply with the following requirements: (a) Prohibited types of heaters. (1) Exhaust heaters. (2) Unenclosed flame heaters. (3) Heaters permitting fuel leakage. (4) Heaters permitting air contamination. (5) Solid fuel heaters except wood charcoal. (6) Portable heaters. (b) Heater specifications. (1) Heating elements, protection. (2) Moving parts, guards. (3) Heaters, secured. (4) Relative motion between fuel tank and heater. (5) Operating controls to be protected. (6) Heater hoses. (7) Electrical apparatus. Note: Electrical parts certified as proper for use by Underwriters' Laboratories, Inc., shall be deemed to comply with the foregoing requirements. (8) Storage battery caps. (9) Combustion heater exhaust construction. Provided, however, (10) Combustion chamber construction. (11) Heater fuel tank location. (12) Heater, automatic fuel control. (13) “Tell-tale” indicators. (14) Shut-off control. (15) Certification required. (c) Exception. [33 FR 19735, Dec. 25, 1968, as amended at 40 FR 51198, Nov. 4, 1975; 53 FR 49401, Dec. 7, 1988; 77 FR 59828, Oct. 1, 2012; 78 FR 58484, Sept. 24, 2013] § 393.78 Windshield wiping and washing systems. (a) Vehicles manufactured on or after December 25, 1968. (b) Vehicles manufactured between June 30, 1953, and December 24, 1968. (c) Driveaway-towaway operations. [70 FR 48054, Aug. 15, 2005] § 393.79 Windshield defrosting and defogging systems. (a) Vehicles manufactured on or after December 25, 1968. (b) Vehicles manufactured before December 25, 1968. [70 FR 48054, Aug. 15, 2005] § 393.80 Rear-vision mirrors. (a) Every bus, truck, and truck tractor shall be equipped with two rear-vision mirrors, one at each side, firmly attached to the outside of the motor vehicle, and so located as to reflect to the driver a view of the highway to the rear, along both sides of the vehicle. All such regulated rear-vision mirrors and their replacements shall meet, as a minimum, the requirements of FMVSS No. 111 (49 CFR 571.111) in force at the time the vehicle was manufactured. (b) Exceptions. (2) Only one outside mirror shall be required, which shall be on the driver's side, on trucks which are so constructed that the driver has a view to the rear by means of an interior mirror. (3) In driveway-towaway operations, the driven vehicle shall have at least one mirror furnishing a clear view to the rear. [48 FR 57139, Dec. 28, 1983, as amended at 66 FR 49874, Oct. 1, 2001] § 393.81 Horn. Every bus, truck, truck-tractor, and every driven motor vehicle in driveaway-towaway operations shall be equipped with a horn and actuating elements which shall be in such condition as to give an adequate and reliable warning signal. § 393.82 Speedometer. Each bus, truck, and truck-tractor must be equipped with a speedometer indicating vehicle speed in miles per hour and/or kilometers per hour. The speedometer must be accurate to within plus or minus 8 km/hr (5 mph) at a speed of 80 km/hr (50 mph). [70 FR 48054, Aug. 15, 2005] § 393.83 Exhaust systems. (a) Every motor vehicle having a device (other than as part of its cargo) capable of expelling harmful combustion fumes shall have a system to direct the discharge of such fumes. No part shall be located where its location would likely result in burning, charring, or damaging the electrical wiring, the fuel supply, or any combustible part of the motor vehicle. (b) No exhaust system shall discharge to the atmosphere at a location immediately below the fuel tank or the fuel tank filler pipe. (c) The exhaust system of a bus powered by a gasoline engine shall discharge to the atmosphere at or within 6 inches forward of the rearmost part of the bus. (d) The exhaust system of a bus using fuels other than gasoline shall discharge to the atmosphere either: (1) At or within 15 inches forward of the rearmost part of the vehicle; or (2) To the rear of all doors or windows designed to be open, except windows designed to be opened solely as emergency exits. (e) The exhaust system of every truck and truck tractor shall discharge to the atmosphere at a location to the rear of the cab or, if the exhaust projects above the cab, at a location near the rear of the cab. (f) No part of the exhaust system shall be temporarily repaired with wrap or patches. (g) No part of the exhaust system shall leak or discharge at a point forward of or directly below the driver/sleeper compartment. The exhaust outlet may discharge above the cab/sleeper roofline. (h) The exhaust system must be securely fastened to the vehicle. (i) Exhaust systems may use hangers which permit required movement due to expansion and contraction caused by heat of the exhaust and relative motion between engine and chassis of a vehicle. [53 FR 49401, Dec. 7, 1988] § 393.84 Floors. The flooring in all motor vehicles shall be substantially constructed, free of unnecessary holes and openings, and shall be maintained so as to minimize the entrance of fumes, exhaust gases, or fire. Floors shall not be permeated with oil or other substances likely to cause injury to persons using the floor as a traction surface. [53 FR 49401, Dec. 7, 1988] § 393.85 [Reserved] § 393.86 Rear impact guards and rear end protection. (a)(1) General requirements for trailers and semitrailers manufactured on or after January 26, 1998. (2) Impact guard width. (3) Guard height. (4) Guard rear surface. (5) Cross-sectional vertical height. (6) [Reserved] (b)(1) Requirements for motor vehicles manufactured after December 31, 1952 (except trailers or semitrailers manufactured on or after January 26, 1998). (i) The vertical distance between the bottom of the guard(s) and the ground does not exceed 76.2 cm (30 inches) when the motor vehicle is empty; (ii) The maximum lateral distance between the closest points between guards, if more than one is used, does not exceed 61 cm (24 inches); (iii) The outermost surfaces of the horizontal member of the guard are no more than 45.7 cm (18 inches) from each side extremity of the motor vehicle; (iv) The impact guard(s) are no more than 61 cm (24 inches) forward of the rear extremity of the motor vehicle. (2) Construction and attachment. (3) Vehicle components and structures that may be used to satisfy the requirements of paragraph (b) of this section. [64 FR 47708, Sept. 1, 1999, as amended at 67 FR 61824, Oct. 2, 2002; 86 FR 62111, Nov. 9, 2021; 91 FR 7877, Feb. 19, 2026] § 393.87 Warning flags on projecting loads. (a) Any commercial motor vehicle transporting a load which extends beyond the sides by more than 102 mm (4 inches) or more than 1,219 mm (4 feet) beyond the rear must have the extremities of the load marked with red or orange fluorescent warning flags. Each warning flag must be at least 457 mm (18 inches) square. (b) Position of flags. [70 FR 48054, Aug. 15, 2005] § 393.88 Television receivers. Any motor vehicle equipped with a television viewer, screen or other means of visually receiving a television broadcast shall have the viewer or screen located in the motor vehicle at a point to the rear of the back of the driver's seat if such viewer or screen is in the same compartment as the driver and the viewer or screen shall be so located as not to be visible to the driver, while he/she is driving the motor vehicle. The operating controls for the television receiver shall be so located that the driver cannot operate them without leaving the driver's seat. § 393.89 Buses, driveshaft protection. Any driveshaft extending lengthways under the floor of the passenger compartment of a bus shall be protected by means of at least one guard or bracket at that end of the shaft which is provided with a sliding connection (spline or other such device) to prevent the whipping of the shaft in the event of failure thereof or of any of its component parts. A shaft contained within a torque tube shall not require any such device. [33 FR 19735, Dec. 25, 1968, as amended at 53 FR 49402, Dec. 7, 1988] § 393.90 Buses, standee line or bar. Except as provided below, every bus, which is designed and constructed so as to allow standees, shall be plainly marked with a line of contrasting color at least 2 inches wide or equipped with some other means so as to indicate to any person that he/she is prohibited from occupying a space forward of a perpendicular plane drawn through the rear of the driver's seat and perpendicular to the longitudinal axis of the bus. Every bus shall have clearly posted at or near the front, a sign with letters at least one-half inch high stating that it is a violation of the Federal Motor Carrier Safety Administration's regulations for a bus to be operated with persons occupying the prohibited area. The requirements of this section shall not apply to any bus being transported in driveaway-towaway operation or to any level of the bus other that the level in which the driver is located nor shall they be construed to prohibit any seated person from occupying permanent seats located in the prohibited area provided such seats are so located that persons sitting therein will not interfere with the driver's safe operation of the bus. § 393.91 Buses, aisle seats prohibited. No bus shall be equipped with aisle seats unless such seats are so designed and installed as to automatically fold and leave a clear aisle when they are unoccupied. No bus shall be operated if any seat therein is not securely fastened to the vehicle. [53 FR 49402, Dec. 7, 1988] § 393.92 [Reserved] § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses Buses manufactured on or after January 1, 1965, and before July 1, 1971. 1 1 1 (2) Buses manufactured on or after July 1, 1971. 1 1 (3) Buses manufactured on or after January 1, 1972. 1 (b) Trucks and truck tractors Trucks and truck tractors manufactured on and after January 1, 1965, and before July 1, 1971. (2) Trucks and truck tractors manufactured on or after July 1, 1971. 1 1 1 (3) Trucks and truck tractors manufactured on or after January 1, 1972. 1 (c) Effective date of standards. (d) Trucks and truck tractors manufactured on or after January 1, 1965, and before July 1, 1971, and operated in the State of Hawaii, must comply with the provisions of paragraph (b) of this section on and after January 1, 1976. [35 FR 16839, Oct. 30, 1970, as amended at 39 FR 32561, Sept. 9, 1974; 40 FR 32336, Aug. 1, 1975; 72 FR 55703, Oct. 1, 2007] § 393.94 Interior noise levels in power units. (a) Applicability of this section. (b) General rule. (c) Test procedure. (2) Close all vehicle doors, windows, and vents. Turn off all power-operated accessories. (3) Place the driver in his/her normal seated position at the vehicle's controls. Evacuate all occupants except the driver and the person conducting the test. (4) The sound level meters used to determine compliance with the requirements of this section must meet the American National Standards Institute “Specification for Sound Level Meters,” (5) Locate the microphone, oriented vertically upward, 6 inches to the right of, in the same plane as, and directly in line with, the driver's right ear. (6) With the vehicle's transmission in neutral gear, accelerate its engine to either its maximum governed engine speed, if it is equipped with an engine governor, or its speed at its maximum rated horsepower, if it is not equipped with an engine governor. Stabilize the engine at that speed. (7) Observe the A-weighted sound level reading on the meter for the stabilized engine speed condition. Record that reading, if the reading has not been influenced by extraneous noise sources such as motor vehicles operating on adjacent roadways. (8) Return the vehicle's engine speed to idle and repeat the procedures specified in paragraphs (c) (6) and (7) of this section until two maximum sound levels within 2 dB of each other are recorded. Numerically average those two maximum sound level readings. (9) The average obtained in accordance with paragraph (c)(8) of this section is the vehicle's interior sound level at the driver's seating position for the purpose of determining whether the vehicle conforms to the rule in paragraph (b) of this section. However, a 2 dB tolerance over the sound level limitation specified in that paragraph is permitted to allow for variations in test conditions and variations in the capabilities of meters. (10) If the motor vehicle's engine radiator fan drive is equipped with a clutch or similar device that automatically either reduces the rotational speed of the fan or completely disengages the fan from its power source in response to reduced engine cooling loads the vehicle may be parked before testing with its engine running at high idle or any other speed the operator may choose, for sufficient time but not more than 10 minutes, to permit the engine radiator fan to automatically disengage. [38 FR 30881, Nov. 8, 1973, as amended at 40 FR 32336, Aug. 1, 1975; 41 FR 28268, July 9, 1976; 70 FR 48054, Aug. 15, 2005] Subpart H—Emergency Equipment § 393.95 Emergency equipment on all power units. Each truck, truck tractor, and bus (except those towed in driveaway-towaway operations) must be equipped as follows: (a) Fire extinguishers Minimum ratings. (ii) A power unit that is not used to transport hazardous materials must be equipped with either: (A) A fire extinguisher having an Underwriters' Laboratories rating of 5 B:C or more; or (B) Two fire extinguishers, each of which has an Underwriters' Laboratories rating of 4 B:C or more. (2) Labeling and marking. (3) Visual Indicators. (4) Condition, location, and mounting. (5) Extinguishing agents. (6) Exception. (b)-(e) [Reserved] (f) Warning devices for stopped vehicles. (1) Three bidirectional emergency reflective triangles that conform to the requirements of Federal Motor Vehicle Safety Standard No. 125, § 571.125 of this title; or (2) At least 6 fusees. The vehicle must have as many additional fusees as are necessary to satisfy the requirements of § 392.22 of this chapter. (3) Other warning devices may be used in addition to, but not in lieu of, the required warning devices, provided those warning devices do not decrease the effectiveness of the required warning devices. (g) Restrictions on the use of flame-producing devices. (h)-(i) [Reserved] (j) Requirements for fusees. (k) Requirements for red flags. [33 FR 19735, Dec. 25, 1968, as amended at 35 FR 13019, Aug. 15, 1970; 35 FR 14619, Sept. 18, 1970; 37 FR 17176, Aug. 25, 1972; 40 FR 10685, Mar. 7, 1975; 41 FR 53031, Dec. 3, 1976; 47 FR 47837, Oct. 28, 1982; 59 FR 34712, July 6, 1994; 67 FR 61225, Sept. 27, 2002; 70 FR 48054, Aug. 15, 2005; 72 FR 44036, Aug. 7, 2007; 78 FR 58484, Sept. 24, 2013; 80 FR 59075, Oct. 1, 2015; 91 FR 7870, Feb. 19, 2026; 91 FR 7880, Feb. 19, 2026] Subpart I—Protection Against Shifting and Falling Cargo Source: 67 FR 61225, Sept. 27, 2002, unless otherwise noted. § 393.100 Applicability and general requirements of cargo securement standards. (a) Applicability. (b) Prevention against loss of load. (c) Prevention against shifting of load. § 393.102 Minimum performance criteria for cargo securement devices and systems. (a) Performance criteria Breaking strength. (i) 0.8 g deceleration in the forward direction; (ii) 0.5 g acceleration in the rearward direction; and (iii) 0.5 g acceleration in a lateral direction. (2) Working Load limit. (i) 0.435 g deceleration in the forward direction; (ii) 0.5 g acceleration in the rearward direction; and (iii) 0.25 g acceleration in a lateral direction. (b) Performance criteria for devices to prevent vertical movement of loads that are not contained within the structure of the vehicle. (c) Equivalent means of securement. (1) Immobilized, such so that it cannot shift or tip to the extent that the vehicle's stability or maneuverability is adversely affected; or (2) Transported in a sided vehicle that has walls of adequate strength, such that each article of cargo within the vehicle is in contact with, or sufficiently close to a wall or other articles, so that it cannot shift or tip to the extent that the vehicle's stability or maneuverability is adversely affected; or (3) Secured in accordance with the applicable requirements of §§ 393.104 through 393.136. [71 FR 35832, June 22, 2006, as amended at 78 FR 58484, Sept. 24, 2013] § 393.104 Standards for cargo securement devices and systems. (a) General. (b) Prohibition on the use of damaged securement devices. (c) Vehicle structures and anchor points. (d) Material for dunnage, chocks, cradles, shoring bars, blocking and bracing. (e) Manufacturing standards for tiedown assemblies. An assembly component of . . . Must conform to . . . (1) Steel strapping 1 2 Standard Specification for Strapping, Flat Steel and Seals, American Society for Testing and Materials (ASTM) D3953-97, February 1998. 4 (2) Chain National Association of Chain Manufacturers' Welded Steel Chain Specifications, dated September 28, 2005. 4 (3) Webbing Web Sling and Tiedown Association's Recommended Standard Specification for Synthetic Web Tiedowns, WSTDA-T1, 1998. 4 (4) Wire rope 3 Wire Rope Technical Board's Wire Rope Users Manual, 2nd Edition, November 1985. 4 (5) Cordage Cordage Institute rope standard: (i) PETRS-2, Polyester Fiber Rope, three-Strand and eight-Strand Constructions, January 1993; 4 (ii) PPRS-2, Polypropylene Fiber Rope, three-Strand and eight-Strand Constructions, August 1992; 4 (iii) CRS-1, Polyester/Polypropylene Composite Rope Specifications, three-Strand and eight-Strand Standard Construction, May 1979; 4 (iv) NRS-1, Nylon Rope Specifications, three-Strand and eight-Strand Standard Construction, May 1979; 4 (v) C-1, Double Braided Nylon Rope Specifications DBN, January 1984. 4 1 2 3 4 (f) Use of tiedowns. (2) If a tiedown is repaired, it must be repaired in accordance with the applicable standards in paragraph (e) of this section, or the manufacturer's instructions. (3) Each tiedown must be attached and secured in a manner that prevents it from becoming loose, unfastening, opening or releasing while the vehicle is in transit. (4) Edge protection must be used whenever a tiedown would be subject to abrasion or cutting at the point where it touches an article of cargo. The edge protection must resist abrasion, cutting and crushing. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35833, June 22, 2006] § 393.106 General requirements for securing articles of cargo. (a) Applicability. e.g. (b) General. (c) Cargo placement and restraint. (2) Articles or cargo placed beside each other and secured by transverse tiedowns must either: (i) Be placed in direct contact with each other, or (ii) Be prevented from shifting towards each other while in transit. (d) Aggregate working load limit for tiedowns. (1) One-half the working load limit of each tiedown that goes from an anchor point on the vehicle to an anchor point on an article of cargo; (2) One-half the working load limit of each tiedown that is attached to an anchor point on the vehicle, passes through, over, or around the article of cargo, and is then attached to an anchor point on the same side of the vehicle. (3) The working load limit for each tiedown that goes from an anchor point on the vehicle, through, over, or around the article of cargo, and then attaches to another anchor point on the other side of the vehicle. [67 FR 61225, Sept. 27, 2002, as amended at 68 FR 56208, Sept. 30, 2003; 71 FR 35833, June 22, 2006] § 393.108 Determining the working load limit of a tiedown or the load restraining value of a friction mat. (a) The working load limit (WLL) of a tiedown, associated connector or attachment mechanism is the lowest working load limit of any of its components (including tensioner), or the working load limit of the anchor points to which it is attached, whichever is less. (b) The working load limits of tiedowns may be determined by using either the tiedown manufacturer's markings or by using the tables in this section. The working load limits listed in the tables are to be used when the tiedown material is not marked by the manufacturer with the working load limit. Tiedown materials which are marked by the manufacturer with working load limits that differ from the tables, shall be considered to have a working load limit equal to the value for which they are marked. (c) Synthetic cordage ( e.g., (d) Welded steel chain which is not marked or labeled to enable identification of its grade or working load limit shall be considered to have a working load limit equal to that for grade 30 proof coil chain. (e)(1) Wire rope which is not marked by the manufacturer with a working load limit shall be considered to have a working load limit equal to one-fourth of the nominal strength listed in the Wire Rope Users Manual. (2) Wire which is not marked or labeled to enable identification of its construction type shall be considered to have a working load limit equal to that for 6 × 37, fiber core wire rope. (f) Manila rope which is not marked by the manufacturer with a working load limit shall be considered to have a working load limit based on its diameter as provided in the tables of working load limits. (g) Friction mats which are not marked or rated by the manufacturer shall be considered to provide resistance to horizontal movement equal to 50 percent of the weight placed on the mat. Tables to § 393.108 [Working Load Limits (WLL), Chain] Size mm (inches) WLL in kg (pounds) Grade 30 proof coil Grade 43 high test Grade 70 transport Grade 80 alloy Grade 100 alloy 1. 7 (1/4) 580 (1,300) 1,180 (2,600) 1,430 (3,150) 1,570 (3,500) 1,950 (4,300) 2. 8 (5/16) 860 (1,900) 1,770 (3,900) 2,130 (4,700) 2,000 (4,500) 2,600 (5,700) 3. 10 (3/8) 1,200 (2,650) 2,450 (5,400) 2,990 (6,600) 3,200 (7,100) 4,000 (8,800) 4. 11 (7/16) 1,680 (3,700) 3,270 (7,200) 3,970 (8,750) 5. 13 (1/2) 2,030 (4,500) 4,170 (9,200) 5,130 (11,300) 5,400 (12,000) 6,800 (15,000) 6. 16 (5/8) 3,130 (6,900) 5,910 (13,000) 7,170 (15,800) 8,200 (18,100) 10,300 (22,600) Chain Mark Examples: Example 1 3 4 7 8 10 Example 2 30 43 70 80 100 Example 3 300 430 700 800 1000 Synthetic Webbing Width mm (inches) WLL kg (pounds) 45 (1 3 4 790 (1,750) 50 (2) 910 (2,000) 75 (3) 1,360 (3,000) 100 (4) 1,810 (4,000) Wire Rope (6 × 37, Fiber Core) Diameter mm (inches) WLL kg (pounds) 7 (1/4) 640 (1,400) 8 (5/16) 950 (2,100) 10 (3/8) 1,360 (3,000) 11 (7/16) 1,860 (4,100) 13 (1/2) 2,400 (5,300) 16 (5/8) 3,770 (8,300) 20 (3/4) 4,940 (10,900) 22 (7/8) 7,300 (16,100) 25 (1) 9,480 (20,900) Manila Rope Diameter mm (inches) WLL kg (pounds) 10 (3/8) 90 (205) 11 (7/16) 120 (265) 13 (1/2) 150 (315) 16 (5/8) 210 (465) 20 (3/4) 290 (640) 25 (1) 480 (1,050) Polypropylene Fiber Rope WLL (3-Strand and 8-Strand Constructions) Diameter mm (inches) WLL kg (pounds) 10 (3/8) 180 (400) 11 (7/16) 240 (525) 13 (1/2) 280 (625) 16 (5/8) 420 (925) 20 (3/4) 580 (1,275) 25 (1) 950 (2,100) Polyester Fiber Rope WLL (3-Strand and 8-Strand Constructions) Diameter mm (inches) WLL kg (pounds) 10 (3/8) 250 (555) 11 (7/16) 340 (750) 13 (1/2) 440 (960) 16 (5/8) 680 (1,500) 20 (3/4) 850 (1,880) 25 (1) 1,500 (3,300) Nylon Rope Diameter mm (inches) WLL kg (pounds) 10 (3/8) 130 (278) 11 (7/16) 190 (410) 13 (1/2) 240 (525) 16 (5/8) 420 (935) 20 (3/4) 640 (1,420) 25 (1) 1,140 (2,520) Double Braided Nylon Rope Diameter mm (inches) WLL kg (pounds) 10 (3/8) 150 (336) 11 (7/16) 230 (502) 13 (1/2) 300 (655) 16 (5/8) 510 (1,130) 20 (3/4) 830 (1,840) 25 (1) 1,470 (3,250) Steel Strapping Width × thickness mm (inches) WLL kg (pounds) 31.7 × .74 (1 1 4 540 (1,190) 31.7 × .79 (1 1 4 540 (1,190) 31.7 × .89 (1 1 4 540 (1,190) 31.7 × 1.12 (1 1 4 770 (1,690) 31.7 × 1.27 (1 1 4 770 (1,690) 31.7 × 1.5 (1 1 4 870 (1,925) 50.8 × 1.12 (2 × 0.044) 1,200 (2,650) 50.8 × 1.27 (2 × 0.05) 1,200 (2,650) § 393.110 Additional requirements for determining the minimum number of tiedowns. (a) When tiedowns are used as part of a cargo securement system, the minimum number of tiedowns required to secure an article or group of articles against movement depends on the length of the article(s) being secured, and the requirements of paragraphs (b) and (c) of this section. These requirements are in addition to the rules under § 393.106. (b) When an article is not blocked or positioned to prevent movement in the forward direction by a headerboard, bulkhead, other cargo that is positioned to prevent movement, or other appropriate blocking devices, it must be secured by at least: (1) One tiedown for articles 5 feet (1.52 meters) or less in length, and 1,100 pounds (500 kg) or less in weight; (2) Two tiedowns if the article is: (i) 5 feet (1.52 meters) or less in length and more than 1,100 pounds (500 kg) in weight; or (ii) Longer than 5 feet (1.52 meters) but less than or equal to 10 feet (3.04 meters) in length, irrespective of the weight. (3) Two tiedowns if the article is longer than 10 feet (3.04 meters), and one additional tiedown for every 10 feet (3.04 meters) of article length, or fraction thereof, beyond the first 10 feet (3.04 meters) of length. (c) If an individual article is blocked, braced, or immobilized to prevent movement in the forward direction by a headerboard, bulkhead, other articles which are adequately secured or by an appropriate blocking or immobilization method, it must be secured by at least one tiedown for every 3.04 meters (10 feet) of article length, or fraction thereof. (d) Special rule for special purpose vehicles. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35833, June 22, 2006] § 393.112 Adjustability of tiedowns. Each tiedown, or its associated connectors, or its attachment mechanisms must be designed, constructed, and maintained so the driver of an in-transit commercial motor vehicle can tighten them. However, this requirement does not apply to the use of steel strapping. § 393.114 Requirements for front end structures used as part of a cargo securement system. (a) Applicability. (b) Height and width. (2) The front end structure must have a width which is at least equal to the width of the vehicle or which blocks forward movement of any article of cargo being transported on the vehicle, whichever is narrower. (c) Strength. (1) For a front end structure less than 6 feet in height, a horizontal forward static load equal to one-half (0.5) of the weight of the articles of cargo being transported on the vehicle uniformly distributed over the entire portion of the front end structure that is within 4 feet above the vehicle's floor or that is at or below a height above the vehicle's floor at which it blocks forward movement of any article of the vehicle's cargo, whichever is less; or (2) For a front end structure 6 feet in height or higher, a horizontal forward static load equal to four-tenths (0.4) of the weight of the articles of cargo being transported on the vehicle uniformly distributed over the entire front end structure. (d) Penetration resistance. (e) Substitute devices. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35833, June 22, 2006] Specific Securement Requirements by Commodity Type § 393.116 Specific securement requirements for logs. (a) Applicability. (1) Logs that are unitized by banding or other comparable means may be transported in accordance with the general cargo securement rules of §§ 393.100 through 393.114. (2) Loads that consist of no more than four processed logs may be transported in accordance with the general cargo securement rules of §§ 393.100 through 393.114. (3) Firewood, stumps, log debris and other such short logs must be transported in a vehicle or container enclosed on both sides, front, and rear and of adequate strength to contain them. Longer logs may also be so loaded. (b) Components of a securement system. (2) All vehicle components involved in securement of logs must be designed and built to withstand all anticipated operational forces without failure, accidental release or permanent deformation. Stakes or standards that are not permanently attached to the vehicle must be secured in a manner that prevents unintentional separation from the vehicle in transit. (3) Tiedowns must be used in combination with the stabilization provided by bunks, stakes, and bolsters to secure the load unless the logs: (i) are transported in a crib-type log trailer (as defined in 49 CFR 393.5), and (ii) are loaded in compliance with paragraphs (b)(2) and (c) of this section. (4) The aggregate working load limit for tiedowns used to secure a stack of logs on a frame vehicle, or a flatbed vehicle equipped with bunks, bolsters, or stakes must be at least one-sixth the weight of the stack of logs. (c) Use of securement system. (2) Each outside log on the side of a stack of logs must touch at least two stakes, bunks, bolsters, or standards. If one end does not actually touch a stake, it must rest on other logs in a stable manner and must extend beyond the stake, bunk, bolster or standard. (3) The center of the highest outside log on each side or end must be below the top of each stake, bunk or standard. (4) Each log that is not held in place by contact with other logs or the stakes, bunks, or standards must be held in place by a tiedown. Additional tiedowns or securement devices must be used when the condition of the wood results in such low friction between logs that they are likely to slip upon each other. (d) Securement of shortwood logs loaded crosswise on frame, rail and flatbed vehicles. (1) In no case may the end of a log in the lower tier extend more than one-third of the log's total length beyond the nearest supporting structure on the vehicle. (2) When only one stack of shortwood is loaded crosswise, it must be secured with at least two tiedowns. The tiedowns must attach to the vehicle frame at the front and rear of the load, and must cross the load in this direction. (3) When two tiedowns are used, they must be positioned at approximately one-third and two-thirds of the length of the logs. (4) A vehicle that is more than 10 meters (33 feet) long must be equipped with center stakes, or comparable devices, to divide it into sections approximately equal in length. Where a vehicle is so divided, each tiedown must secure the highest log on each side of the center stake, and must be fastened below these logs. It may be fixed at each end and tensioned from the middle, or fixed in the middle and tensioned from each end, or it may pass through a pulley or equivalent device in the middle and be tensioned from one end. (5) Any structure or stake that is subjected to an upward force when the tiedowns are tensioned must be anchored to resist that force. (6) If two stacks of shortwood are loaded side-by-side, in addition to meeting the requirements of paragraphs (d)(1) through (d)(5) of this section, they must be loaded so that: (i) There is no space between the two stacks of logs; (ii) The outside of each stack is raised at least 2.5 cm (1 in) within 10 cm (4 in) of the end of the logs or the side of the vehicle; (iii) The highest log is no more than 2.44 m (8 ft) above the deck; and (iv) At least one tiedown is used lengthwise across each stack of logs. (e) Securement of logs loaded lengthwise on flatbed and frame vehicles Shortwood. (i) Secured to the vehicle by at least two tiedowns, or (ii) If all the logs in any stack are blocked in the front by a front-end structure strong enough to restrain the load, or by another stack of logs, and blocked in the rear by another stack of logs or vehicle end structure, the stack may be secured with one tiedown. If one tiedown is used, it must be positioned about midway between the stakes, or (iii) Be bound by at least two tiedown-type devices such as wire rope, used as wrappers that encircle the entire load at locations along the load that provide effective securement. If wrappers are being used to bundle the logs together, the wrappers are not required to be attached to the vehicle. (2) Longwood. (i) Be secured to the vehicle by at least two tiedowns at locations that provide effective securement, or (ii) Be bound by at least two tiedown-type devices, such as wire rope, used as wrappers that encircle the entire load at locations along the load that provide effective securement. If a wrapper(s) is being used to bundle the logs together, the wrapper is not required to be attached to the vehicle. (f) Securement of logs transported on pole trailers. (2) The front and rear wrappers must be at least 3.04 meters (10 feet) apart. (3) Large diameter single and double log loads must be immobilized with chock blocks or other equivalent means to prevent shifting. (4) Large diameter logs that rise above bunks must be secured to the underlying load with at least two additional wrappers. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35833, June 22, 2006] § 393.118 Specific securement requirements for dressed lumber and similar building products. (a) Applicability. (b) Positioning of bundles. (c) Securement of bundles transported using no more than one tier. (d) Securement of bundles transported using more than one tier. (1) Blocked against lateral movement by stakes on the sides of the vehicle and secured by tiedowns laid out over the top tier, as outlined in the general provisions of §§ 393.100 through 393.114; or (2) Restrained from lateral movement by blocking or high friction devices between tiers and secured by tiedowns laid out over the top tier, as outlined in the general provisions of §§ 393.100 through 393.114; or (3) Placed directly on top of other bundles or on spacers and secured in accordance with the following: (i) The length of spacers between bundles must provide support to all pieces in the bottom row of the bundle. (ii) The width of individual spacers must be equal to or greater than the height. (iii) If spacers are comprised of layers of material, the layers must be unitized or fastened together in a manner which ensures that the spacer performs as a single piece of material. (iv) The arrangement of the tiedowns for the bundles must be: (A) Secured by tiedowns over the top tier of bundles, in accordance with the general provisions of §§ 393.100 through 393.114 with a minimum of two tiedowns for bundles longer than 1.52 meters (5 ft); and (B) Secured by tiedowns as follows: ( 1 ( 2 i ( ii (4) Secured by tiedowns over each tier of bundles, in accordance with §§ 393.100 through 393.114 using a minimum of two tiedowns over each of the top bundles longer than 1.52 meters (5 ft), in all circumstances; or (e) When loaded in a sided vehicle or container of adequate strength, dressed lumber or similar building products may be secured in accordance with the general provisions of §§ 393.100 through 393.114. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35834, June 22, 2006; 78 FR 58484, Sept. 24, 2013] § 393.120 Specific securement requirements for metal coils. (a) Applicability. (b) Securement of coils transported with eyes vertical on a flatbed vehicle, in a sided vehicle or in an intermodal container with anchor points An individual coil. (i) At least one tiedown attached diagonally from the left side of the vehicle or intermodal container (near the forwardmost part of the coil), across the eye of the coil, to the right side of the vehicle or intermodal container (near the rearmost part of the coil); (ii) At least one tiedown attached diagonally from the right side of the vehicle or intermodal container (near the forwardmost part of the coil), across the eye of the coil, to the left side of the vehicle or intermodal container (near the rearmost part of the coil); (iii) At least one tiedown attached transversely over the eye of the coil; and (iv) Either blocking and bracing, friction mats or tiedowns to prevent longitudinal movement in the forward direction. (2) Coils grouped in rows. (i) At least one tiedown attached to the front of the row of coils, restraining against forward motion, and whenever practicable, making an angle no more than 45 degrees with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; (ii) At least one tiedown attached to the rear of the row of coils, restraining against rearward motion, and whenever practicable, making an angle no more than 45 degrees with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; (iii) At least one tiedown over the top of each coil or transverse row of coils, restraining against vertical motion. Tiedowns going over the top of a coil(s) must be as close as practicable to the eye of the coil and positioned to prevent the tiedown from slipping or becoming unintentionally unfastened while the vehicle is in transit; and (iv) Tiedowns must be arranged to prevent shifting or tipping in the forward, rearward and lateral directions. (c) Securement of coils transported with eyes crosswise on a flatbed vehicle, in a sided vehicle or in an intermodal container with anchor points An individual coil. (i) A means ( e.g., (ii) At least one tiedown through its eye, restricting against forward motion, and whenever practicable, making an angle no more than 45 degrees with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; and (iii) At least one tiedown through its eye, restricting against rearward motion, and whenever practicable, making an angle no more than 45 degrees with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container. (2) Prohibition on crossing of tiedowns when coils are transported with eyes crosswise. (d) Securement of coils transported with eyes lengthwise on a flatbed vehicle, in a sided vehicle or in an intermodal container with anchor points An individual coil-option 1. (i) A means ( e.g., (ii) At least one tiedown attached diagonally through its eye from the left side of the vehicle or intermodal container (near the forward-most part of the coil), to the right side of the vehicle or intermodal container (near the rearmost part of the coil), making an angle no more than 45 degrees, whenever practicable, with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; (iii) At least one tiedown attached diagonally through its eye, from the right side of the vehicle or intermodal container (near the forward-most part of the coil), to the left side of the vehicle or intermodal container (near the rearmost part of the coil), making an angle no more than 45 degrees, whenever practicable, with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; (iv) At least one tiedown attached transversely over the top of the coil; and (v) Either blocking or friction mats to prevent longitudinal movement. (2) An individual coil—option 2. (i) A means ( e.g., (ii) At least one tiedown attached straight through its eye from the left side of the vehicle or intermodal container (near the forward-most part of the coil), to the left side of the vehicle or intermodal container (near the rearmost part of the coil), and, whenever practicable, making an angle no more than 45 degrees with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; (iii) At least one tiedown attached straight through its eye, from the right side of the vehicle or intermodal container (near the forward-most part of the coil), to the right side of the vehicle or intermodal container (near the rearmost part of the coil), and whenever practicable, making an angle no more than 45 degrees with the floor of the vehicle or intermodal container when viewed from the side of the vehicle or container; (iv) At least one tiedown attached transversely over the top of the coil; and (v) Either blocking or friction mats to prevent longitudinal movement. (3) An individual coil—option 3. (i) A means ( e.g., (ii) At least one tiedown over the top of the coil, located near the forward-most part of the coil; (iii) At least one tiedown over the top of the coil located near the rearmost part of the coil; and (iv) Either blocking or friction mats to prevent longitudinal movement. (4) Rows of coils. (i) A means ( e.g., (ii) At least one tiedown over the top of each coil or transverse row, located near the forward-most part of the coil; (iii) At least one tiedown over the top of each coil or transverse row, located near the rearmost part of the coil; and (iv) Either blocking, bracing or friction mats to prevent longitudinal movement. (e) Securement of coils transported in a sided vehicle without anchor points or an intermodal container without anchor points. [67 FR 61225, Sept. 27, 2002, as amended at 78 FR 58484, Sept. 24, 2013] § 393.122 Specific securement requirements for paper rolls. (a) Applicability. (b) Securement of paper rolls transported with eyes vertical in a sided vehicle. (2) If there are not enough paper rolls in the shipment to reach the walls of the vehicle, lateral movement must be prevented by filling the void, blocking, bracing, tiedowns or friction mats. The paper rolls may also be banded together. (3) When any void behind a group of paper rolls, including that at the rear of the vehicle, exceeds the diameter of the paper rolls, rearward movement must be prevented by friction mats, blocking, bracing, tiedowns, or banding to other rolls. (4)(i) If a paper roll is not prevented from tipping or falling sideways or rearwards by vehicle structure or other cargo, and its width is more than 2 times its diameter, it must be prevented from tipping or falling by banding it to other rolls, bracing, or tiedowns. (ii) If the forwardmost roll(s) in a group of paper rolls has a width greater than 1.75 times its diameter and it is not prevented from tipping or falling forwards by vehicle structure or other cargo, then it must be prevented from tipping or falling forwards by banding it to other rolls, bracing, or tiedowns. (iii) If the forwardmost roll(s) in a group of paper rolls has a width equal to or less than 1.75 times its diameter, and it is restrained against forward movement by friction mat(s) alone, then banding, bracing, or tiedowns are not required to prevent tipping or falling forwards. (iv) If a paper roll or the forwardmost roll in a group of paper rolls has a width greater than 1.25 times its diameter, and it is not prevented from tipping or falling forwards by vehicle structure or other cargo, and it is not restrained against forward movement by friction mat(s) alone, then it must be prevented from tipping or falling by banding it to other rolls, bracing or tiedowns. (5) If paper rolls are banded together, the rolls must be placed tightly against each other to form a stable group. The bands must be applied tightly, and must be secured so that they cannot fall off the rolls or to the deck. (6) A friction mat used to provide the principal securement for a paper roll must protrude from beneath the roll in the direction in which it is providing that securement. (c) Securement of split loads of paper rolls transported with eyes vertical in a sided vehicle. (2) A friction mat used to provide the principal securement for a paper roll must protrude from beneath the roll in the direction in which it is providing that securement. (d) Securement of stacked loads of paper rolls transported with eyes vertical in a sided vehicle. (2) Paper rolls in the second and subsequent layers must be prevented from forward, rearward or lateral movement by means as allowed for the bottom layer, or by use of a blocking roll from a lower layer. (3) The blocking roll must be at least 38 mm (1.5 in) taller than other rolls, or must be raised at least 38 mm (1.5 in) using dunnage. (4) A roll in the rearmost row of any layer raised using dunnage may not be secured by friction mats alone. (e) Securement of paper rolls transported with eyes crosswise in a sided vehicle. (2) Chocks, wedges or blocking must be held securely in place by some means in addition to friction, so they cannot become unintentionally unfastened or loose while the vehicle is in transit. (3) The rearmost roll must not be secured using the rear doors of the vehicle or intermodal container, or by blocking held in place by those doors. (4) If there is more than a total of 203 mm (8 in) of space between the ends of a paper roll, or a row of rolls, and the walls of the vehicle, void fillers, blocking, bracing, friction mats, or tiedowns must be used to prevent the roll from shifting towards either wall. (f) Securement of stacked loads of paper rolls transported with eyes crosswise in a sided vehicle. (2) Rolls must not be loaded in a third or higher layer unless all wells in the layer beneath are filled. (3) The foremost roll in each upper layer, or any roll with an empty well in front of it, must be secured against forward movement by: (i) Banding it to other rolls, or (ii) Blocking against an adequately secured eye-vertical blocking roll resting on the floor of the vehicle which is at least 1.5 times taller than the diameter of the roll being blocked, or (iii) Placing it in a well formed by two rolls on the lower row whose diameter is equal to or greater than that of the roll on the upper row. (4) The rearmost roll in each upper layer must be secured by banding it to other rolls if it is located in either of the last two wells formed by the rearmost rolls in the layer below. (5) Rolls must be secured against lateral movement by the same means allowed for the bottom layer when there is more than a total of 203 mm (8 in) of space between the ends of a paper roll, or a row of rolls, and the walls of the vehicle. (g) Securement of paper rolls transported with the eyes lengthwise in a sided vehicle. (2) Each roll must be prevented from rearward movement by contact with other cargo, blocking, friction mats or tiedowns. (3) The paper rolls must be prevented from rolling or shifting laterally by contact with the wall of the vehicle or other cargo, or by chocks, wedges or blocking of adequate size. (4) Chocks, wedges or blocking must be held securely in place by some means in addition to friction, so they cannot become unintentionally unfastened or loose while the vehicle is in transit. (h) Securement of stacked loads of paper rolls transported with the eyes lengthwise in a sided vehicle. (2) An upper layer must be formed by placing paper rolls in the wells formed by the rolls beneath. (3) A roll in an upper layer must be secured against forward and rearward movement by any of the means allowed for the bottom layer, by use of a blocking roll, or by banding to other rolls. (i) Securement of paper rolls transported on a flatbed vehicle or in a curtain-sided vehicle Paper rolls with eyes vertical or with eyes lengthwise. (ii) Stacked loads of paper rolls with eyes vertical are prohibited. (2) Paper rolls with eyes crosswise. (ii) Chocks, wedges or blocking must be held securely in place by some means in addition to friction so that they cannot become unintentionally unfastened or loose while the vehicle is in transit. (iii) Tiedowns must be used in accordance with the requirements of §§ 393.100 through 393.114 to prevent lateral movement. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35834, June 22, 2006] § 393.124 Specific securement requirements for concrete pipe. (a) Applicability. (2) Concrete pipe bundled tightly together into a single rigid article that has no tendency to roll, and concrete pipe loaded in a sided vehicle or container must be secured in accordance with the provisions of §§ 393.100 through 393.114. (b) General specifications for tiedowns. (2) A transverse tiedown through a pipe on an upper tier or over longitudinal tiedowns is considered to secure all those pipes beneath on which that tiedown causes pressure. (c) Blocking. (2) One piece must extend at least half the distance from the center to each end of the pipe, and two pieces must be placed on the opposite side, one at each end of the pipe. (3) Blocking must be placed firmly against the pipe, and must be secured to prevent it moving out from under the pipe. (4) Timber blocking must have minimum dimensions of at least 10 × 15 cm (4 × 6 in). (d) Arranging the load Pipe of different diameter. (2) Arranging a bottom tier. (3) Arranging an upper tier. (4) Arranging the top tier. (5) Arranging bell pipe. (ii) Bell pipe loaded in one tier must have the bells alternating on opposite sides of the vehicle. (iii) The ends of consecutive pipe must be staggered, if possible, within the allowable width, otherwise they must be aligned. (iv) Bell pipe loaded in more than one tier must have the bells of the bottom tier all on the same side of the vehicle. (v) Pipe in every upper tier must be loaded with bells on the opposite side of the vehicle to the bells of the tier below. (vi) If the second tier is not complete, pipe in the bottom tier which do not support a pipe above must have their bells alternating on opposite sides of the vehicle. (e) Securing pipe with an inside diameter up to 1,143 mm (45 in). (1) Stabilizing the bottom tier. (ii) Other pipe in the bottom tier may also be held in place by blocks and/or wedges; and (iii) Every pipe in the bottom tier must also be held firmly in contact with the adjacent pipe by tiedowns though the front and rear pipes: (A) At least one tiedown through the front pipe of the bottom tier must run aft at an angle not more than 45 degrees with the horizontal, whenever practicable. (B) At least one tiedown through the rear pipe of the bottom tier must run forward at an angle not more than 45 degrees with the horizontal, whenever practicable. (2) Use of tiedowns. (ii) If each pipe is not secured individually with a tiedown, then: (A) Either one 1/2-inch diameter chain or wire rope, or two 3/8-inch diameter chain or wire rope, must be placed longitudinally over the group of pipes; (B) One transverse tiedown must be used for every 3.04 m (10 ft) of load length. The transverse tiedowns may be placed through a pipe, or over both longitudinal tiedowns between two pipes on the top tier; (C) If the first pipe of a group in the top tier is not placed in the first well formed by pipes at the front of the tier beneath, it must be secured by an additional tiedown that runs rearward at an angle not more than 45 degrees to the horizontal, whenever practicable. This tiedown must pass either through the front pipe of the upper tier, or outside it and over both longitudinal tiedowns; and (D) If the last pipe of a group in the top tier is not placed in the last well formed by pipes at the rear of the tier beneath, it must be secured by an additional tiedown that runs forward at an angle not more than 45 degrees to the horizontal, whenever practicable. This tiedown must pass either through the rear pipe of the upper tier or outside it and over both longitudinal tiedowns. (f) Securing large pipe, with an inside diameter over 1143 mm (45 in). (1) The front pipe and the rear pipe must be immobilized by blocking, wedges, vehicle end structure, stakes, locked pipe unloader, or other equivalent means. (2) Each pipe must be secured by tiedowns through the pipe: (i) At least one tiedown through each pipe in the front half of the load, which includes the middle one if there is an odd number, and must run rearward at an angle not more than 45 degrees with the horizontal, whenever practicable; (ii) At least one tiedown through each pipe in the rear half of the load, and must run forward at an angle not more than 45 degrees with the horizontal, whenever practicable, to hold each pipe firmly in contact with adjacent pipe; and (iii) If the front or rear pipe is not also in contact with vehicle end structure, stakes, a locked pipe unloader, or other equivalent means, at least two tiedowns positioned as described in paragraphs (f)(2)(i) and (ii) of this section, must be used through that pipe. (3) If only one pipe is transported, or if several pipes are transported without contact between other pipes, the requirements in this paragraph apply to each pipe as a single front and rear article. [67 FR 61225, Sept. 27, 2002, as amended at 78 FR 58484, Sept. 24, 2013] § 393.126 Specific securement requirements for intermodal containers. (a) Applicability. (b) Securement of intermodal containers transported on container chassis vehicle(s). (2) The securement devices must restrain the container from moving more than 1.27 cm (1/2 in) forward, more than 1.27 cm (1/2 in) aft, more than 1.27 cm (1/2 in) to the right, more than 1.27 cm (1/2 in) to the left, or more than 2.54 cm (1 in) vertically. (3) The front and rear of the container must be secured independently. (c) Securement of loaded intermodal containers transported on vehicles other than container chassis vehicle(s). (2) Each container must be secured to the vehicle by: (i) Chains, wire ropes or integral devices which are fixed to all lower corners; or (ii) Crossed chains which are fixed to all upper corners; and, (3) The front and rear of the container must be secured independently. Each chain, wire rope, or integral locking device must be attached to the container in a manner that prevents it from being unintentionally unfastened while the vehicle is in transit. (d) Securement of empty intermodal containers transported on vehicles other than container chassis vehicle(s). (1) The empty intermodal container is balanced and positioned on the vehicle in a manner such that the container is stable before the addition of tiedowns or other securement equipment; and, (2) The amount of overhang for the empty container on the trailer does not exceed five feet on either the front or rear of the trailer; (3) The empty intermodal container must not interfere with the vehicle's maneuverability; and, (4) The empty intermodal container is secured to prevent lateral, longitudinal, or vertical shifting. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35834, June 22, 2006] § 393.128 Specific securement requirements for automobiles, light trucks, and vans. (a) Applicability. (b) Securement of automobiles, light trucks, and vans. (2) Tiedowns that are designed to be affixed to the structure of the automobile, light truck, or van must use the mounting points on those vehicles that have been specifically designed for that purpose. (3) Tiedowns that are designed to fit over or around the wheels of an automobile, light truck, or van must provide restraint in the lateral, longitudinal and vertical directions. (4) Edge protectors are not required for synthetic webbing at points where the webbing comes in contact with the tires. § 393.130 Specific securement requirements for heavy vehicles, equipment, and machinery. (a) Applicability. (b) Preparation of equipment being transported. (2) Articulated vehicles shall be restrained in a manner that prevents articulation while in transit. (c) Securement of heavy vehicles, equipment or machinery with crawler tracks or wheels. (2) Each of the tiedowns must be affixed as close as practicable to the front and rear of the vehicle, or mounting points on the vehicle that have been specifically designed for that purpose. § 393.132 Specific securement requirements for flattened or crushed vehicles. (a) Applicability. (b) Prohibition on the use of synthetic webbing. (c) Securement of flattened or crushed vehicles. (1) Containment walls or comparable means on four sides which extend to the full height of the load and which block against movement of the cargo in the forward, rearward and lateral directions; or (2)(i) Containment walls or comparable means on three sides which extend to the full height of the load and which block against movement of the cargo in the direction for which there is a containment wall or comparable means, and (ii) A minimum of two tiedowns are required per vehicle stack; or (3)(i) Containment walls on two sides which extend to the full height of the load and which block against movement of the cargo in the forward and rearward directions, and (ii) A minimum of three tiedowns are required per vehicle stack; or (4) A minimum of four tiedowns per vehicle stack. (5) In addition to the requirements of paragraphs (c)(2), (3), and (4), the following rules must be satisfied: (i) Vehicles used to transport flattened or crushed vehicles must be equipped with a means to prevent liquids from leaking from the bottom of the vehicle, and loose parts from falling from the bottom and all four sides of the vehicle extending to the full height of the cargo. (ii) The means used to contain loose parts may consist of structural walls, sides or sideboards, or suitable covering material, alone or in combinations. (iii) The use of synthetic material for containment of loose parts is permitted. [67 FR 61225, Sept. 27, 2002, as amended at 71 FR 35834, June 22, 2006] § 393.134 Specific securement requirements for roll-on/roll-off and hook lift containers. (a) Applicability. (b) Securement of a roll-on/roll-off and hook lift container. (1) Blocked against forward movement by the lifting device, stops, a combination of both or other suitable restraint mechanism; (2) Secured to the front of the vehicle by the lifting device or other suitable restraint against lateral and vertical movement; (3) Secured to the rear of the vehicle with at least one of the following mechanisms: (i) One tiedown attached to both the vehicle chassis and the container chassis; (ii) Two tiedowns installed lengthwise, each securing one side of the container to one of the vehicle's side rails; or (iii) Two hooks, or an equivalent mechanism, securing both sides of the container to the vehicle chassis at least as effectively as the tiedowns in the two previous items. (4) The mechanisms used to secure the rear end of a roll-on/roll off or hook lift container must be installed no more than two meters (6 ft 7 in) from the rear of the container. (5) In the event that one or more of the front stops or lifting devices are missing, damaged or not compatible, additional manually installed tiedowns must be used to secure the container to the vehicle, providing the same level of securement as the missing, damaged or incompatible components. § 393.136 Specific securement requirements for large boulders. (a) Applicability. (2) Pieces of rock weighing more than 100 kg (220 lb.), but less than 5,000 kg (11,000 lb.) must be secured, either in accordance with this section, or in accordance with the provisions of §§ 393.100 through 393.114, including: (i) Rock contained within a vehicle which is designed to carry such cargo; or (ii) Secured individually by tiedowns, provided each piece can be stabilized and adequately secured. (3) Rock which has been formed or cut to a shape and which provides a stable base for securement must also be secured, either in accordance with the provisions of this section, or in accordance with the provisions of §§ 393.100 through 393.114. (b) General requirements for the positioning of boulders on the vehicle. (2) Each boulder must be supported on at least two pieces of hardwood blocking at least 10 cm × 10 cm (4 inches × 4 inches) side dimensions extending the full width of the boulder. (3) Hardwood blocking pieces must be placed as symmetrically as possible under the boulder and should support at least three-fourths of the length of the boulder. (4) If the flattest side of a boulder is rounded or partially rounded, so that the boulder may roll, it must be placed in a crib made of hardwood timber fixed to the deck of the vehicle so that the boulder rests on both the deck and the timber, with at least three well-separated points of contact that prevent its tendency to roll in any direction. (5) If a boulder is tapered, the narrowest end must point towards the front of the vehicle. (c) General tiedown requirements. (2) Tiedowns which are in direct contact with the boulder should, where possible, be located in valleys or notches across the top of the boulder, and must be arranged to prevent sliding across the rock surface. (d) Securement of a cubic shaped boulder. (1) Each boulder must be secured individually with at least two chain tiedowns placed transversely across the vehicle. (2) The aggregate working load limit of the tiedowns must be at least half the weight of the boulder. (3) The tiedowns must be placed as closely as possible to the wood blocking used to support the boulder. (e) Securement of a non-cubic shaped boulder—with a stable base. (1) The boulder must be secured individually with at least two chain tiedowns forming an “X” pattern over the boulder. (2) The aggregate working load limit of the tiedowns must be at least half the weight of the boulder. (3) The tiedowns must pass over the center of the boulder and must be attached to each other at the intersection by a shackle or other connecting device. (f) Securement of a non-cubic shaped boulder—with an unstable base. (1) One chain must surround the top of the boulder (at a point between one-half and two-thirds of its height). The working load limit of the chain must be at least half the weight of the boulder. (2) Four chains must be attached to the surrounding chain and the vehicle to form a blocking mechanism which prevents any horizontal movement. Each chain must have a working load limit of at least one-fourth the weight of the boulder. Whenever practicable, the angle of the chains must not exceed 45 degrees from the horizontal. [67 FR 61225, Sept. 27, 2002, as amended at 78 FR 58484, Sept. 24, 2013] Subpart J—Frames, Cab and Body Components, Wheels, Steering, and Suspension Systems Source: 53 FR 49402, Dec. 7, 1988, unless otherwise noted. § 393.201 Frames. (a) The frame or chassis of each commercial motor vehicle shall not be cracked, loose, sagging or broken. (b) Bolts or brackets securing the cab or the body of the vehicle to the frame must not be loose, broken, or missing. (c) The frame rail flanges between the axles shall not be bent, cut or notched, except as specified by the manufacturer. (d) Parts and accessories shall not be welded to the frame or chassis of a commercial motor vehicle except in accordance with the vehicle manufacturer's recommendations. Any welded repair of the frame must also be in accordance with the vehicle manufacturer's recommendations. (e) No holes shall be drilled in the top or bottom rail flanges, except as specified by the manufacturer. [53 FR 49402, Dec. 7, 1988, as amended at 70 FR 48055, Aug. 15, 2005] § 393.203 Cab and body components. (a) The cab compartment doors or door parts used as an entrance or exits shall not be missing or broken. Doors shall not sag so that they cannot be properly opened or closed. No door shall be wired shut or otherwise secured in the closed position so that it cannot be readily opened. Exception: (b) Bolts or brackets securing the cab or the body of the vehicle to the frame shall not be loose, broken, or missing. (c) The hood must be securely fastened. (d) All seats must be securely mounted. (e) The front bumper must not be missing, loosely attached, or protruding beyond the confines of the vehicle so as to create a hazard. [53 FR 49402, Dec. 7, 1988, as amended at 78 FR 58484, Sept. 24, 2013] § 393.205 Wheels. (a) Wheels and rims shall not be cracked or broken. (b) Stud or bolt holes on the wheels shall shall not be elongated (out of round). (c) Nuts or bolts shall not be missing or loose. § 393.207 Suspension systems. (a) Axles. (b) Adjustable axles. (c) Leaf springs. (d) Coil springs. (e) Torsion bar. (f) Air suspensions. (g) Air suspension exhaust controls. (1) Devices that could exhaust air from both axle systems simultaneously; or (2) Lift axles on multi-axle units. [53 FR 49402, Dec. 7, 1988, as amended at 70 FR 48055, Aug. 15, 2005] § 393.209 Steering wheel systems. (a) The steering wheel shall be secured and must not have any spokes cracked through or missing. (b) Steering wheel lash. Steering wheel diameter Manual steering system Power steering system 406 mm or less (16 inches or less) 51 mm (2 inches) 108 mm (4 1 4 457 mm (18 inches) 57 mm (2 1 4 121 mm (4 3 4 483 mm (19 inches) 60 mm (2 3 8 127 mm (5 inches). 508 mm (20 inches) 64 mm (2 1 2 133 mm (5 1 4 533 mm (21 inches) 67 mm (2 5 8 140 mm (5 1 2 559 mm (22 inches) 70 mm (2 3 4 146 mm (5 3 4 (2) For steering wheel diameters not listed in paragraph (b)(1) of this section the steering wheel lash shall not exceed 14 degrees angular rotation for manual steering systems, and 30 degrees angular rotation for power steering systems. (c) Steering column. (d) Steering system. (e) Power steering systems. [53 FR 49402, Dec. 7, 1988, as amended at 70 FR 48055, Aug. 15, 2005]

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