High noise while moving (abonrmal sound from gearbox)
Cause of failure:
1. Abnormal sound of drive wheel: wheel and axle not fitting perfectly. Replace wheel or axle.
2. Abnormal noise of drive motor: motor bearing grinding inner ring
3. Abnormal sound of gearbox: gear damage
Checking method:
1. Keep the truck off ground, remove drive wheel. If abnormal sound is gone, replace the drive wheel or wheel axle.
2. If abnormal sound still exists, temporarily remove motor, and push accelerator switch. If abnormal sound is gone, replace gear box; If abnormal sound still exists, replace drive motor.