I've got a Zimmerman 32' foot double chain (I think it's a model 380) and a 32' Little Giant double chain. I also have a 16' aluminum Harvest Handler.
My grandfather had a JI Case E-2 which was a single chain that had moveable side sheets so you could make it an enclosed grain elevator, 1/3 of the way open for ear corn, 2/3 open for moving bags, or all the way open for bales.