Typical Front Wheel Disc Brake Component Layout
1 - Brake hose; 2 - Caliper; 3 - Brake disc; 4 - Caliper guide pin
Typical Rear Wheel Disc Brake Component Layout
1 - Caliper; 2 - Caliper bolts; 3 - Brake hose; 4 - Brake disc
General information
All brake mechanisms have a self-adjusting design. At the same time, compensation for wear of the brake pads of disc mechanisms (front and rear) It is carried out automatically, while special adjusting devices are installed on the drum brake mechanisms, the activation of which occurs during braking, as well as when the parking brake is cocked.
Twin design equipped with two separate reservoirs of the main brake cylinder (GTZ) allows you to split the hydraulic path into two circuits that operate independently of each other. The latter means that in the event of a failure of one of the circuits, the second continues to operate in the same mode, providing adequate braking of the car. The hydraulic circuits are arranged diagonally. Failure of any of the circuits, of course, leads to a decrease in braking efficiency and is accompanied by the operation of a warning lamp on the instrument panel when the foot brake pedal is depressed.
Master brake cylinder (GTZ)
The GTZ is mounted on the brake booster servo assembly mounted on the rear bulkhead of the engine compartment. On top of the cylinder is a large hydraulic fluid reservoir equipped with a plastic cap. The tank is fastened with a clamp.
As mentioned above, the GTZ has a dual design that provides the operation of two independent hydraulic circuits. The fluid pressure in each of the circuits is pumped by an individual piston inside the main cylinder.
Regulator valve
In addition to the vacuum booster, a double-circuit rear brake pressure regulator is included in the hydraulic drive of the brake system. The pressure control valve is installed on the rear bulkhead of the vehicle's engine compartment. On equipped with anti-lock brakes (ABS) the valve is built into the hydraulic modulator block located on the right side of the engine compartment.
The control valve is included in both circuits of the brake system and provides pressure limitation in the hydraulic drive of the brake mechanisms of the rear wheels, preventing their premature blocking during heavy braking. The valve is activated when the hydraulic pressure in the circuits reaches a certain value.
The regulator is non-repairable and, in case of failure, must be replaced as an assembly.
Vacuum brake booster
The booster uses the vacuum created in the intake piping to improve the efficiency of the hydraulic brake system. The vacuum booster servo is mounted on the rear bulkhead of the engine compartment.
Parking brake
The parking brake control lever is located in the passenger compartment. Attached to the lever is a single front drive cable, which in turn is connected to a pair of rear cables. When cocking the lever on models equipped with drum rear brakes, the rear cables pull back on the actuating levers attached to the brake shoe assemblies in both rear wheel mechanisms. In this case, the shoes are bred to the sides, pressing against the working surface of the drums. On models with rear wheel disc brakes, the actuating arms are attached to screw-type actuators in the caliper housings. The levers act on the caliper pistons, forcing the pads to press against the brake discs.
Precautionary measures
Some special precautions should be observed when servicing vehicle brake system components:
- a) Use only DOT 3 grade hydraulic fluid to fill the brake system;
- b) Friction linings of brake pads/shoes may contain hazardous asbestos. Try not to inhale brake dust, do not blow it off with compressed air. To wipe the components of the brake mechanisms, use only special cleaning compounds;
- c) Ensure that all required tolerances and tightening torques of fasteners are observed. When servicing components, use only serviceable tools. At the slightest doubt, seek help from specialists. Remember that the proper functioning of the brakes is the key to traffic safety;
- d) Never attempt to disconnect hydraulic brake system components on models equipped with ABS. Remember that bleeding the hydraulic path on such vehicles is carried out using special equipment;
- e) At the slightest sign of a malfunction in the functioning of the brake system, the operation of the car should be suspended!