Electric Park Brake Actuators
| ITEM | DESCRIPTION |
|---|---|
| 1 | Brake caliper |
| 2 | Spindle |
| 3 | Seal |
| 4 | EPB actuator |
| 5 | Screw (quantity 2) |
| 6 | Output shaft |
The EPB actuators are electro-mechanical positioning units attached to the rear brake calipers. Each EPB actuator incorporates a reversible electric motor driving an output shaft through a worm drive gear.
The output shaft of the EPB actuator is engaged in the splined end of a spindle. The spindle is inside the caliper piston and screwed into a ball screw drive. Operation of the electric motor turns the spindle and produces linear movement of the ball screw drive. The linear movement applies a target clamp load to the brake pads.
Operation of each EPB actuator is controlled by the ABS through 2 hardwired connections with the electric motor. The ABS changes the polarity of the connections to change the direction of drive of the motor.
When the EPB is applied, the electric motor turns the spindle to press against the caliper piston and apply the brake. The ABS measures the current draw of the electric motor. The ABS disconnects the power supply when it equates to a clamp load of 18.7 kN being applied to the caliper piston.
When the EPB is released, the electric motor turns the spindle for approximately 800 milliseconds to retract the spindle. This will release the pressure on the caliper piston.