The best changeover is using 2 1" Dema hp solenoid valves. The motorized ball valve uses a small 24vac solenoid valve to shift from u/c to the gantry. Usually the 2 allen screws that hold the solenoid valve in place will strip out and allow air to leak. Get the Demas from KR. It will take a little creative wiring to make them work as the 3/4" feed to the gantry needs to be normally open. The Demas are normally closed. Wire it in to the "STOP" light, which will open it when the car reaches the treadle. Wire the U/C valve into where the u/c is wired now. Hope this helps. Let me know if you need part numbers.