gearbox torque?!? Hi, I don't know much about mechanics and I'm trying to build a mechanism to drive a set of syringes, and I need to buy a gearbox motor to drive the syringe shaft forward and back. the syringe needs to be driven 70mm, and i'm going to attach a rack and gear to the motor to get this motion. however, because of the hydraulics, it actually requires quite a bit of force, and i don't know what gearbox motor will be strong enough to drive it. i didn't know how to measure how much force i need so i put weights on the shaft and it needs 2.5kg to drive forward at a good speed. (it doesn't have to be incredibly fast but i don't want it to be terribly slow either). could anyone recommend a motor that will be strong enough to drive it at a good pace?? or tell me what information and numbers to look for in the data sheet?? thanks so much!!