Elements of the rear brake drum
1 - clamping safety washer; 2 - shield of the brake mechanism; 3 - passive brake shoe; 4 - dustproof cuff of the wheel brake cylinder; 5 - wheel brake cylinder; 6 - upper coupling spring; 7 - active brake shoe; 8 - coupling spring of the parking brake strut; 9 - parking brake spacer; 10 - adjusting nut; 11 - clamping brake pads; 12 - parking brake cable; 13 - brake pad support; 14 - lower coupling spring; 15 - lever for manual drive of pads with limiter.
The rear drum brakes consist of 2 semi-circular brake pads which are actuated by the wheel brake cylinder (cylinder with two pistons). The brake pads are mounted on the opposite side of the brake cylinder, on a support riveted to the shield of the brake mechanism. Such a design of a drum brake mechanism, with one brake cylinder, is called a wheel brake mechanism with one expansion device for both pads (simplex brake).
The drum brake mechanism operates with a certain gain. This means that the brake shoe is attracted by the rotation of the wheel to the brake drum. As a result, less effort is required when depressing the brake pedal. When the vehicle is moving forward, the front brake pad acts with reinforcement. It is called the incoming, or primary, brake shoe, as opposed to the rear, descending and, accordingly, the secondary brake shoe.