I saw a question posted in one thread on The Gauge regarding couplers to use on a rotary dumper. I don't know if an answer was given, and I don't model coaltrains or rotary dumpers so it wasn't something I was familier with at all. I was just looking at the Sergent Engineering web page for some other information and noticed that they offer a working dummy rotary coupler. It can't be uncoupled and coupled automatically, but if you are going to run a unit coal train over a rotary dumper, uncoupling probably isn't necessary. Check it out at http://user.icx.net/!sergent/ If this info was already given to the individual asking, my apologies, but in case it wasn't I'm going to throw this out. I have the box to automatically parse links in the text, but aparantly the board doesn't recognise the url for Sergent Engineering as a link.