Maybe

I found this while I was looking for more information:

From:
[www.patentstorm.us]

"At present, such replacement knuckles are AAR Standard knuckles which weigh approximately 78 to 88 pounds, and are carried in the locomotive section of a train. In some cases, it may be necessary for a single operator to carry such a knuckle the length of 25, 50 or even 100 railroad cars to reach a defective knuckle which needs replacement. Then the operator much manipulate the replacement knuckle into position on the coupler, after the damaged knuckle is removed, which is no simple task. In fact, it is a necessary and important job, but a back breaking one to say the least. The invention is designed to alleviate this problem by the provision of a substantially lighter weight knuckle which weighs only about 48 pounds and can be used in an emergency to replace a defective AAR Standard knuckle in most knuckle type railroad car couplers. "

Bruce