Section 17, act May 30, 1908, ch. 225, §§ 1, 2, 35 Stat. 476 , related to locomotives to be equipped with safety ash pans. Section 18, acts May 30, 1908, ch. 225, § 3, 35 Stat. 476 ; June 25, 1948, ch. 646, § 1, 62 Stat. 909 ; Oct. 15, 1966 , Pub. L. 89–670, § 6(e)(1)(D) , 80 Stat. 939 , set forth penalties for violations and authorized United States attorneys to bring actions for enforcement of provisions. Section 19, acts May 30, 1908, ch. 225, § 4, 35 Stat. 476 ; Oct. 15, 1966 , Pub. L. 89–670, § 6(e)(1)(D) , 80 Stat. 939 , provided for enforcement of the provisions of sections 17 to 21 of this title by the Secretary of Transportation. Section 20, act May 30, 1908, ch. 225, § 5, 35 Stat. 476 , specified those to be included in the term “common carrier”. Section 21, act May 30, 1908, ch. 225, § 6, 35 Stat. 476 , provided that the provisions of sections 17 to 21 of this title not be applicable to locomotives on which an ash pan is not necessary.