Drum Brake System Description & Operation
For exploded view of drum brake system, see Fig 1 .
The rear drum brake assembly is a leading/trailing design. Pressure on the brake pedal applies pressure on the master cylinder. The master cylinder increases the brake fluid pressure. The brake fluid applies pressure on the wheel cylinder pistons. The wheel cylinder pistons move both brake shoes out in order to contact the drum. The brake shoes contact the drum and apply enough friction to overcome the rotation of the drum, the wheels, and the tires. The slowing of the rotation of the tires slows the vehicle. Continued application of the brakes stops the vehicle.
Applying the brakes automatically adjusts the brake shoes. Normally, the primary brake shoe will wear at a faster rate than the secondary brake shoe. If you remove and reinstall the brake shoes, reinstall the brake shoes in the same position from which you removed the brake shoes. DO NOT switch the position of brake shoes that have been in service. Switching the position of the brake shoes may render the automatic adjustment feature inoperative and result in increased pedal travel.