[Jared]

I think those old bottom dumps were just trip the doors and let 'er fly. They were moving big yardages and get it dumped and back for another load was the name of the game. They opened by gravity trip and had some method or other of closing. I know some had a cable running to each door and up to a winch that was driven off the back tires. I would probably mount a servo on the back, put a sheave or pulley on the end of a horn and run a string/cable/what have you from one door, through the sheave and back to the other door so they will be equalized. Or just run it directly through a hole in the horn. Use a switched channel so its either open or closed with the flip of a switch. That's what I would do, anyway.