49 CFR 229.61 - Draft system.
(a) A coupler may not have any of the following conditions:
(1) A distance between the guard arm and the knuckle nose of more than 5 5/16 inches on D&E couplers.
(2) A crack or break in the side wall or pin bearing bosses outside of the shaded areas shown in Figure 1 or in the pulling face of the knuckle.
(3) A coupler assembly without anti-creep protection.
(4) Free slack in the coupler or drawbar not absorbed by friction devices or draft gears that exceeds one-half inches.
(5) A broken or cracked coupler carrier.
(6) A broken or cracked yoke.
(7) A broken draft gear.
(b) A device shall be provided under the lower end of all drawbar pins and articulated connection pins to prevent the pin from falling out of place in case of breakage.