Help with Drive Motor Issue in Clawbot


We have built Clawbot and I installed the firmware updates.

I turned on the brain to use the built in programs with the user control. The left hand motor seems to be operating perfectly (gears and wheels moving) but the right hand motor is just making a sound with nothing really happening (no gears or wheels moving). Consequently the robot is basically only moving in a circular motion as only the left hand motor is working. Left hand motor is plugged into port 1 of the brain and right hand motor is plugged into port 6, as requested by documentation. I have checked that cables are also inserted correctly.

Anyone have any idea as to what the problem could be? Many thanks in advance.

This is commonly caused by the axle shaft that connects the wheels to the motor becoming dislodged. The shaft must go all the way into the square hole in the motor.

Here is a video that might help:

Thank you - that would appear to be the problem. When the boys were building it the axel shaft they used was too short so it didn’t even go into the motor. That’s a job sorted for them tomorrow! Thanks again.

Our group of newbies are building 5 clawbots, just to get started. One of the clawbots will only go backward. We made sure the axel is in the motor. We made sure the drive train motors are in 1 and 6 for the default operation. Any suggestions?

Hi SFAC - I responded in your other thread but I can see that ports is not the issue. Do you mean it will drive backwards when the joysticks are pulled backwards, but it doesn’t drive forwards at all?

I believe (but I’m not 100% sure) that if you connect the ultrasonic sensor on the front, the robot will not more forward if something is in front of it. Try unplugging that sensor, and see if that solves the problem.

They fixed that with VEXos Steve. However, it is a valid point, if you have old firmware (i.e. 1.1x) and you have the distance sensor plugged in, you could well experience what you describe.
If you have a distance sensor plugged in, unplug it as Steve suggests and see if it fixes it. If it does, you should upgrade your firmware to VEXos on all devices