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Module 1 - More on Drum and Disc Brakes (Page 1 of 3)

Brakes can be divided into two basic systems:

1. Service Brakes

Service brakes are the system used during normal driving conditions. These brakes are used to control the speed of the vehicle and to stop it when required. The service brakes can also be used to hold the vehicle stationary.

The service brakes are used intermittently - they are not designed to be applied for long period of time (ie: like parking brakes)

The service brake system includes the following parts: brake pedal, master cylinder, brake booster, hydraulic lines, rotors, calipers, pads, drums, wheel cylinders, shoes.

2. Parking brakes

The parking brakes are designed to hold the vehicle stationary when it is left unattended. The parking brake may apply the vehicle service brakes or may be independent.

The parking brake is often mistaken for an emergency brake and may be used for this purpose as a last resort. It has limited braking ability and a low life expectancy if used in this manner.

The parking brake system is often integrated with the rear brakes. Perhaps the most common design is the cable-actuated drum brake system. Quite simply, the driver pulls a racheting lever which in turn pulls on a cable operates a strut / lever inside the brake drum. This strut / lever spreads the brake shoes inside the drum brake and holds the vehicle stationary.

Vehicles that use rear disc brakes also utilize a parking brake system that is built into the brake caliper itself. The driver will pull the parking brake lever which is connected by a cable to a lever on the caliper. As thus lever turns, the pistons inside the caliper expand outward and squeezes the pads against the rotor thereby holding the vehicle stationary.

Module 1 - (Page 1 of 3)