I had the cotter pin come out on a trailer hitch once, and the trailer - fortunately, empty at the time - came loose but was kept off the ground by the short, crossed-over chains. The trailer rocked from side to side with some vigor, but I was able to pull off the side of the highway without incident. I walked back and found the trailer hitch pin, a bit scuffed up but still serviceable, but no cotter pin. I secured the hitch pin with a double loop of baling wire till I got to my destination a few miles away, then replaced it with a new cotter pin.