S-3.3, r. 2 - Regulation respecting rail safety
53. The supervisor must remove from service, until it is repaired, a car that shows one of the following defects:
(1) a coupler shank is bent out of alignment to the extent that the coupler will not couple automatically;
(2) a coupler yoke is broken;
(3) a draft key or a draft key retainer is inoperative or missing;
(4) a vertical coupler pin retainer plate or a follower plate is missing or broken;
(5) a coupler knuckle is broken or cracked on the inside pulling face of the knuckle; or
(6) a coupler pin retainer is missing or broken.