Hi guys, new here to the forum. I was an electrical engineering student but am now working on more of a mechanical issue so I'm a bit out of my element. I am working with a small electric motor attached to a gearbox. The final gear opens and closes a metal valve. I am having trouble finding a combination of motor torque/rpm and gear ratio that successfully accomplishes what we need. Too much torque and the valve is damaged, too little and the valve gets pushed back open by air pressure. Through my research and experimenting, it seems that a high gear ratio, with a low torque motor should accomplish what I need. It is my thought that, the high gear ratio requires more reverse force to push the valve back open from air alone. Through testing the higher gear sets are way more difficult to turn the valve (but is this due to gear ratio alone or also resistance on the motor gear?). But a low torqued motor should still be able to turn the gears and will not over torque the valve. For reference, the gear sets I have tested so far are between the ratios of 400 and 1100. I am hopefully calculating these right. Each gear set has either 4 or 5 compound gears (so 8-10 in total). I am working on getting motor specs, but I am unsure if there's any way I can actually calculate torque on the motor. Does final gear RPM*gear ratio determine motor rpm? Because final gear is very slow and easy to observe/measure. Thanks for the help! I apologize if I'm a bit off on my thinking.