49 CFR §215.123

1. (a)The car is equipped with a coupler shank that is bent out of alignment to the extent that the coupler will not couple automatically with the adjacent car;
2. (b)The car has a coupler that has a crack in the highly stressed junction area of the shank and head as shown in the figure below (see figure 2).
3. (c)The car has a coupler knuckle that is broken or cracked on the inside pulling face of the knuckle.
4. (d)The car has a knuckle pin or knuckle thrower that is:
   1. (1)Missing; or
   2. (2)Inoperative; or
5. (e)The car has a coupler retainer pin lock that is—
   1. (1)Missing; or
   2. (2)Broken; or
6. (f)The car has a coupler with any of the following conditions:
   1. (1)The locklift is inoperative;
   2. (2)The coupler assembly does not have anticreep protection to prevent unintentional unlocking of the coupler lock; or
   3. (3)The coupler lock is—
      1. (i)Missing;
      2. (ii)Inoperative;
      3. (iii)Bent;
      4. (iv)Cracked; or
      5. (v)Broken.