Drum Brake System: Description and Operation

Standard Rear Drum Brake Assembly:

Standard Rear Drum Brake Assembly (cont'd):

Heavy Duty Rear Drum Brake Assembly:

Heavy Duty Rear Drum Brake Assembly (Cont'd):

The rear drum brakes:
^ Have internal shoes that expand against the brake drum.

^ Are a single-anchor type.

^ Are actuated by one rear wheel cylinder.

^ Have two pistons in the rear wheel cylinder. One exerts force against the upper end of the primary shoe; the other exerts force against the upper end of the secondary shoe.

^ Adjust rear brake shoes and linings automatically.

^ Need manual brake adjustment if the adjusters are not operating properly or after the rear brake shoes and linings have been replaced.

^ When the brake pedal is applied, hydraulic fluid pressure forces the pistons in the rear wheel cylinder outward, moving the rear brake shoes and linings against the brake drum.

^ The rear drum brake system includes the parking brake mechanism.