Heat damage to the motor is caused by excessive current. I can think of 3 things that might cause this.the motor is melting. the wires burn as a result.
- 1. You're using more or less voltage than the motor is designed to operate on.
2. The braking mechanism stops the vehicle without shutting off the electricity to the motor.
3. The transmission's gear ratio is too low to produce the torque needed to drive the vehicle.
- 1. Change the battery voltage to what the motor is designed for. (if the motor doesn't have enough power to drive the vehicle, see #3 below.)
2. Add a switch that turns off the motor when the brake is applied.
3. This is the more difficult problem to solve. It's caused by requiring the motor to produce more torque than it's designed for. If you're using just a pulley on the motor shaft connected to the drive wheel/axle with a belt(rubber band?), this may be the case.
The solution is to reduce the necessary torque by reducing overall vehicle weight and/or by increasing the transmission gear ratio. This, of course, may require a lot of design changes to your vehicle.