Knob wheel problems

[pluto7443]

I built my first truck trial vehicle, and it was working fine for about 15 minutes of continous use, however, it soon began to exhibit a problem with knob wheels that I have had before. The knob wheels are in the centre chassis and both axles. They are all mounted basically like this. (I apologize for the large picture, I am using my BlackBerry PlayBook and have no way to resize it ).

After a little while of working fine, the knob wheels will begin to make a loud, kind of screeching/grinding noise. Also, the motor can hardly move the truck on level ground once this occurs. Once it starts, the grinding will continue. I have had this problem before with other high torque uses, such as one vehicle with 3 nxt motors driving one driveshaft. Any ideas to solve this?

[DLuders]

You should get some 100% Silicone Spray at a local auto parts store, and lubricate the Knob Wheels. Whereas the new Knob Wheels probably only contacted each other at small points, over time the contact points grew larger and now there's more friction.