Let's Make Robots!

Custom Gearbox

Hey all I have built a few small scale bots and am now working on a larger 200lb bot. I was wondering if anyone had constructed their own gearbox for a DC motor. If so how did you do it and what kind of gears did you use?


Thank you for any direction you can supply.


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OddBot's picture

You have not specified a voltage for the motors although for a robot that size 24V is fairly common. Windscreen wiper motors from Trucks and Busses are a pretty good as far as power in a compact assembly is concerned. I have one with all metal gears and an output torque of 50Kg/cm.

Another alternative although less compact is to use toothed belts and pulleys. They are smoother and quieter than gears.

ericteuh's picture

Here is two links where you can found some parts or ideas




this next one is in australia, but can be a source of motor models :



Also, you can use the wipers motor, golf cart motors (often 24VDC) or wheelchair motors, all have a strong torque and can be cheap if you buy used.

Maxhirez's picture
http://letsmakerobots.com/node/32683 This unit had a pretty hearty drive mechanism. Custom tank treads and a chain and sprocket drive. It weighs 300 lbs and is made of what he jokingly calls "plytanium" (plywood.). He looks a little like an IPR Marvin to my eye.
Chris the Carpenter's picture

Plytanium is actually a brand name, yo.

Chris the Carpenter's picture

While in reality there are a lot of different ways of moving a 200# robot, for all intents and purposes, there is really only one way:

You're looking for "wheel chair motors" on ebay. If you are lucky, you will score a couple motors and wheels for less than $200. A big SLA battery is $35-50 depending on how big. You can hack the wheel chair's control circuitry (if it comes with it) --if not, you are going to be looking at a very big controller (hundreds of dollars).

Beyond that, I am a fan of chain and sprockets. There is a place called "McMaster Carr" that seems to have everything like this.