OK - I'm trying to sort the pneumatic bead breaker on my Harvey Frost tyre changer so that it doesn't take three pairs of hands to use it. I'm looking for a valve that will supply air in a controlled fashion to extend the ram when you operate it and then allow air to vent freely from the cylinder when it's released. Ideally I'd like the valve to be foot operated. Anybody any idea where I'd get such a beast? Or even what it would be called so I can search? I did get a ball "L" valve but unfortunately between the positions all three ports are connected which means that as well as losing a load of air as you turn the handle you will have little or no control of the ram extending. I've an awful feeling that I'm going to be using two valves - one for supply and one for exhaust. I'm hoping for something with a single operation though if it's available.