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11. Brake system

All models of cars considered in the present manual are equipped with the hydraulic brake system with vacuum strengthening. On forward wheels disk brake mechanisms, on back - both disk, and drum are always installed.
All brake mechanisms are equipped with self-regulators. At the same time compensation of wear of brake shoes of disk mechanisms is carried out automatically whereas, special adjusting devices which activation happens at raising of the parking brake are installed on drum mechanisms.

The Main Brake Cylinder (MBC) is established on the assembly of the servo-driver of the vacuum amplifier of brakes fixed on a back partition of a motive compartment. From above on the cylinder the big tank of hydraulic liquid equipped with a plastic cover is located.

GTTs has the dual design providing functioning of two independent hydraulic contours (forward and back). Liquid pressure in each of contours is forced by the individual piston in separate cameras of the main cylinder. As the GTTs primary piston directly (through a metal rod) is connected to a pedal of a foot brake, movement of the last inevitably leads to increase in hydraulic pressure in brake lines. Instant increase in pressure in lines leads to movement of pistons in supports / wheel cylinders of brake mechanisms, and the size of the effort developed by the last increases in proportion to an increment of the area of their pistons concerning the area of GTTs pistons.

Wheel cylinders of drum brake mechanisms are equipped with two pistons which are pushed out in opposite directions and the brake boots providing a clip to the working surface of the reel. In disk mechanisms cylinders are built in assemblies of supports and provide a possibility of tightening of a brake disk between two frictional blocks.

Brake blocks / boots, and also GTTs pistons are equipped with returnable springs that guarantees transition of system to an initial state at an otpuskaniye of a pedal of a foot brake.

Tightness of landing of pistons in cylinders is provided due to use of rubber sealing cuffs, for protection of cylinders against dirt and moisture special boots are provided.

Main brake cylinder

In the main brake cylinders of double-circuit brake systems two pistons installed directly one after another are used. Primary piston by means of a metal rod is directly connected to a brake pedal. The drive of the secondary piston is carried out in a hydraulic way at the expense of the prisoner between liquid volume pistons. At formation of leaks ahead of the secondary piston, the last is displaced forward against the stop in a face wall of the cylinder and the liquid which is between pistons gets only to a back brake contour of system. At emergence of leaks in a back contour, primary piston rests directly against an end face of secondary, providing isolation of the defective site of the highway.

Hydraulic path

In all dual brake systems the possibility of the warning of the driver of refusal of one of hydraulic contours is realized. The sensor switch is usually built in the case of the valve installed on a back partition of a motive compartment, or on a frame under assembly of GTTs. In the valve there is a piston which is at the same time connected to both contours of a hydraulic path in such a way that pressure developed in them is put to the relevant party of the piston. At serviceable contours of pressure are equal in both contours and the piston remains motionless. Any violation of balance leads to the shift of the piston and short circuit of the sensor switch which chain included the special control lamp established on an instrument guard of the car. Besides the sensor switch also dosing valve providing a delay of giving of pressure in a forward contour until the beginning of operation of drum brake mechanisms of back wheels that allows to avoid braking of the car only one forward wheels can be a part of valvate assembly.

The special valve regulator allows to control pressure in wheel cylinders of back brake mechanisms, preventing thereby premature blocking of back wheels at sharp braking.

Check of serviceability of functioning of a control lamp can be carried out by squeezing of a pedal of a foot brake at the open gate of pumping of one of brake mechanisms. In case of need replace a lamp, or check serviceability of the corresponding electrical wiring and execute necessary recovery repair.

Vacuum amplifier

The special vacuum amplifier who is included in a basic equipment of all models uses the depression created in the inlet pipeline for increase in efficiency of functioning of a hydraulic actuator of the brake system. The servo-driver of the vacuum amplifier is fixed on a back partition of a motive compartment in the last.

System of anti-blocking of brakes (ABS)

ABS prevents premature blocking of wheels of the car at sharp braking (see the Section Replacement of the Sensor Switch of Stoplights).

Parking brake

The hummock drive of the parking brake is brought to brake mechanisms of back wheels of the car. Driving cables are brought to executive levers of assemblies of brake boots.


Upon completion of any of procedures of service connected with removal or dismantling any of components of the brake system without fail check efficiency of functioning of the brake system and having only made sure of full serviceability of its operation, start operation of the car. Trial runs should be made on a pure dry and equal paving.

Check efficiency of braking of the vehicle at various speeds of the movement and various efforts of squeezing of a pedal of a foot brake. The car has to be stopped evenly, keeping at the same time course stability. Try not to allow premature blocking of wheels, fraught loss of control over management.

Remember that the state and pressure of a rating of tires, level of loading of the car and correctness of geometry of a suspension bracket belong to number of the factors making impact on efficiency of braking of the vehicle.

Precautionary measures

At service of components of the brake system of cars it is necessary to observe some special precautionary measures:

a) For gas station of the brake system use only hydraulic liquid of the class DOT 3;
b) Frictional overlays of brake blocks / boots may contain noxious to health asbestos. Try not to inhale brake dust, do not blow off it compressed air. Apply to rubbing of components of brake mechanisms only the special cleaning structures;
c) You monitor observance of all required admissions and efforts of tightening of fixture. At service of components use only the serviceable tool. At the slightest doubts ask for the help experts. Remember that serviceability of functioning of brakes is the key to traffic safety;
d) At the slightest signs of violation of serviceability of functioning of the brake system operation of the car has to be suspended!