Anyone got any ideas on how I can fix my arm

The arm on my robot won’t go up or down. We put another motor on the other side of the driveshaft to make it stronger, but now it’s even worse. Does anyone know what I can do.
Here are some pictures of the robot they are a few days out of date though.

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What color transmissions do you have in those motors? Having more torque might help.


Welcome to the forums. A couple of issues I see with the arm mechanism are the lack of gear ratio, and lack of proper support. If you make the motor power a little gear and the little gear spin your big gear, that will help your arm lift have more strength. Also, make sure that the motors and bearings are mounted well. This might be a friction problem, and it’s always good rule of thumb to have a structurally sound bot. Also, make sure the shaft is all the way in the motor for good measure.


After test driving the bot the other day it did get caught on the supports but we fixed that I didn’t think of the gears though I’ll try that and see how that works thank you


I’m using a red motor It should be the strongest out of all of them

Couple of things.

  1. You need a gear reduction. Direct drive, even with a red cartridge, is not powerful enough.

  2. If adding another motor made it worse, then it sounds like your programming has a problem and is not properly running both motors, at the same time, in the correct direction.

  3. Make sure both motors have the same gear cartridge.

If your having problems when you drive around and tip over I suggest having a low center of gravity on your bot just because you have a arm that goes 180 degrees when you swing the arm around quickly you might tip over something to be aware of when modifying your bot

ok thank we will try that i am in maddox group

If you want a quick solution and you have the resources, you can probably hook up another motor on the side to divvy up the load

I would recommend using aluminum instead of steel if you can.

That motor isn’t strong enough. You need mechanical advantage using a gear ratio.

Below is an image from the Vex Build Instructions - Claw Bot. Notice the 12 tooth gear connected to the motor that drives the larger gear. One motor will give you plenty of power to move the arm if you use the gears to trade speed for power.