I may be wrong, but I think Ted is probably from outside the U.S. I believe that travel trailers are called caravans in Europe or possibly England. The "ball and cup" probably refers to our standard trailer hitch and ball. Just guessing here. Ted, one of the manufactures of the standard ball and hitch is Attwood. Perhaps they can give you the information you seek.
Here is their url. http://www.attwoodmarine.com/produc...Jack&headername=Trailer+Parts+and+Accessories
Hope this helps you out.