Washing machines operate largely on centrifugal force. This is the force created by the spinning of the washer drum, which helps wash the clothes and get rid of the water after the clothes are thoroughly rinsed. Washing machines, however, need a way to monitor their centrifugal speed and keep it within certain parameters. The centrifugal switch acts as this important guard for the washing machine motor.
The centrifugal switch is a circuit component that can either complete a circuit, turning on components of the washer, or disconnect the circuit and keep the components from powering on. When the washer is first turned on, the switch is connected and completes its circuit. When the washing machines reaches a certain speed, the centrifugal action disconnects the switch, essentially slowing down the motor so it does not burn out.
The starting winding of the motor is powered when the drum first starts to turn. It provides a large amount of the necessary force to turn the drum, but eventually the drum builds inertia and no longer needs the help of the starting winding. When the motor reaches approximately 75 percent of its potential speed, the centrifugal switch turns off this starting winding. The drum is then turned using the running winding, which uses less power and does not damage the motor.
The switch has contacts on the stationary side of the drum, mounted on the end bell. These contacts do not move and complete the circuit even when the washing machine does not move. The other set of contacts is connected to the rotor and moves along with the drum. When these two contacts pull apart, the switch turns off. The switch is not one or the other but both sets of contact points working together.
If the washing machine drum refuses to spin at all, the problem is probably associated with the centrifugal switch, which may have become loose or may have burned out. If the clothes come out of the washer dripping wet, it is possible that the centrifugal switch is losing contact too quickly and needs to be adjusted or replaced.