Help with torque calculations and motor sizes!

​I hope it’s ok to post here. I’m working on a robot. I’m trying to calculate the torque and motor sizes needed. I’m no engineer so these are probably simple questions for most here. So…

This machine is scalable to any size. For now I’m making a small version to see how it moves. It should be around 10-15 lbs and I want to make it RC controlled.

There are motor driven main shafts connected to worm gears that help it move. Im looking at a 1,621 rpm brushed planetary gearmotor. 10.9 oz weight. 20 amp current stall and 97.2 oz-in torque stall.

First question:

If I gear it to the main shaft at 2:1 ratio will it double the torque to 194.4 oz-in? Then with the worm gears at 30:1 ratio does that mean torque is 194.4 x 30 = 5,832 oz-in?
30 ft-lb?

Will this be good to move 10-15lbs? It will run slow and smoothly with minimum friction.

2nd question:

I’m using 2 additional gear motors for turning it as it moves. Im looking at two brushed planetary gearmotors. 12V, 12rpm, 8,110 oz-in torque stall, 20 amp current stall motors. I will only use one at a time depending which direction it moves. I want to connect all 3 motors to one rc receiver. Am I ok as long as the receivers amp rating is high enough to cover all three motors combined? Say a 60 amp receiver? All 3 motors have 60 amp stall total.

I hope I can get some help. Thank you!!

Welcome to the community! In order to estimate the torque needed to propel a wheeled robot, we propose you start with the following:


This calculates worst case scenario of the torque needed to accelerate up an incline.

Yes, adding gears can multiply torque and divide speed, but there are losses at every stage, especially with worm gears. You’ll also need to ensure those gears are up to the torque you need.

The RC receiver should not be handling any current - it should only handle the signal, which is sent to DC motor controllers. Take a look here: