1 motor chassis

hey i was just wondering if it was possible to do a legit drive train with 1 motor my teck teacher told me it was possible when we did 2 motor sumo bots last year(not vex). and i cant figure it out. all help would be appreciated

thx in advance

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well if you want it to only go back and forth you just hitch both sides to the motor directly.

I guess one way to turn and go straight is to always power one side while ratcheting the other so that it only spins when the motor is going a specific direction. That wouldn’t be ideal though because you can only go forward and rotate in one direction.


no he said that it could go forward back and turn bolth ways i thought of something similar

It is definitely possible. All you need is sprockets, a high strength shaft, and chain (assuming that you already know that you also need spacers, shaft collars, wheels, etc.). depending on where you can attach the motor (left or right), you can place a high strength shaft through the chassis (drilling holes through where it is going to go, obviously). Then you will need about 8 sprockets to do it right. With a four wheel drive (at least i think that is what you are doing, attach two medium sized sprockets to the shaft that contains the wheels, and then attach small sprockets to the high strength shaft going right through the middle. Do this for both sides. Then run chain from the middle shaft to the wheels on both ends, front and back, for both sides and there you go. A one motor drive. Just know that a one motor drive will have just about no power and just about no speed. It is not an ideal way to make a drive base but at least you will save motors.

What this will be able to run both sides at the same speed, meaning that you will only be able to move forward and backward.

uh… unfortunately you don’t need 8 sprockets for that :stuck_out_tongue:

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yeah u could do that with 4 sprockets

hm, I guess if you really wanted to you could ratchet it so your motor moves between options (drive forward, backward, left,right) when you spin it the opposite way…



That’s a great challenge!

The simplest practical way to have mobility on 2D plane with one motor is what @Deicer proposed - ratcheting one side in one direction.

However, what your teacher wants is, probably, some sort of gear shifting transmission. When you run motor in one direction it shifts among 4 transmission states:

  • both sides are powered in forward direction
  • sides are powered for turning left
  • both sides are powered in reverse direction
  • sides are powered for turning right

And then when you run the motor in other direction it actually powers them
And I just realized @Deicer beat me to this answer again :slight_smile:

Long time ago when I was in middle school I was given as a present remote control with a single button and receiver board that could turn on and off one motor in only one direction. I tried to implement this scheme, when it would switch modes on click-back when power was cut off - it was clearly too complex to me to finish.

Also, if your teacher didn’t say if it is legal to use pneumatics, then you can have shifting implemented with pneumatics. Then everything will be much simpler: you need to have both sides powered in ether same or opposite direction switched with pneumatic gear shift.


Yes you will. unless you have a two-wheel drive. Two for the middle one on one side, this is because you will need to run two chains to each of the big sprockets. Same for the other side. That means that each side has four sprockets. 4 + 4 = 8.

when your motor spins say, clockwise, the motor will move along a rail. Along this rail the counter-clockwise spinning gear falls into other ratcheting mechanisms that power your drive in one direction, left, right, forward, or backward. Have one for each. The clockwise rotation pushes your motor into the desired gearbox like a selector and the counter-clockwise actually powers it


since you can’t turn you can just connect both sides with your axle. Additionally, if your motor powers one of the wheels directly you could use just two total sprockets to connect the the other axle to it.

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Oh yeah, oof. How did I not think of that before? :laughing:

Like a single half of the drive base with one motor? Yeah it’s very possible and even a terrible builder such as myself have done it two different ways, but if you mean the entire drive base with 1 motor then still yeah, just the amount of power output by the single motor will be less for each wheel and you’ll have to do some fancy gear ratios so everything moves in the right direction.


i know this is not for a comp but i was just currious


For IQ, there is this design:


If I’m not mistaken that’s built like a car - one driving motor plus front wheel steering actuation (aka +1 motor)

Pneumatic drive. It’d only last about 30 seconds, but it’d be a cool train-style motion. Then you have your one motor left for a spinning arm of destruction.

That’s 2 motors tho, gyro walker, if this was in a shooting game you can rotate your flywheel and use the torque steer too move forward and turn


Double flywheel. Attach flaps to the flywheels and vary their speed to swim through the air and drag the robot forward.