Front Plate Hubs

The front (pressure) plate is rigidly fixed to the compressor shaft using a spline or keyed connection. When the air conditioner is turned on, the front plate is magnetized to the compressor pulley and torque is transmitted from the belt to the pulley, from the pulley to the pressure plate, from the pressure plate to the compressor shaft itself.

When the system is turned off, the front plate is demagnetized and the pulley rotates "idle" without transmitting any torque to the shaft.

The front plate can wear out prematurely if the system is faulty and operates at elevated pressure.