Hi Frad, I think the rear of the coupler is mounted in an type of box the coupler shank has a travel slot and pin there is a spring assembly that has the rod and couplers attached travel is only about 4" either direction. We used one of the MOW cars years back to go to Antonito during an early Sept snow storm to bring the 484 back we were the helper for the regular train we ha the MOW car and caboose 0503 between the 487? and the reg train after leaving Cumbres with the 2 cars in tow we found the rod had broken at the one end. they did a repair at Antonito and we returned to Chama I guess it still has the temp. repair on it . Fred