I am really challenged as I need to fit a bunch of motors in a 6" box acting as linear actuators. I was looking for linear actuators (most I found were brushed DC) at first but the ones I found that would fit in 6" didn't have a suitable speed torque curve for my application. I started looking at steppers and continuous spin servos, combined with a rack and pinion to transfer the rotational movement into a linear motion.

I need to calculate a linear force resulting from a torque applied on a rack from the pinion gear attached to the spinning motor. Let's say I have a servo applying a torque of 29 kg-cm on the rack, how is this force going to be transferred on the linear rack? (I do not know the pitch and size of rack and pinion yet, but I want to know how big the gear could be to make the rack move faster at a given motor RPM).

Thank you so much!


1 Answer 1


The linear force of the rack is equal to the tangential force on your pinion teeth (less power lost due to friction, typically 2-3% for spur tooth and racks). Tangential force = torque/(pitch diameter/2).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.