Fig. 8.3. Main brake cylinder: 1 — the case; 2 — a tube; 3 — the connecting plug; 4 — a tank; 5 — a protective cap; 6 — the sensor of a signaling device of emergency falling of level of brake fluid; 7 — a persistent ring; 8 — an external cuff; 9 — the directing plug; 10, 17 — pistons; 11 — a lock ring; 12 — a sealing ring; 13 — a piston washer; 14, 16 — cuffs; 15, 18 — persistent washers; 19 — a spring: 20 — a stopper; And, In — compensation openings; With — perepuskny openings

The main brake cylinder with two consistently located pistons 10 and 17 (fig. 8.3) and a two-section tank 4 with the sensor 6 of a signaling device of emergency falling of level of brake fluid fastens to a cover of the vacuum amplifier.

The main brake cylinder creates pressure in two independent hydraulic contours. The volume of brake fluid between pistons 10 and 17 is used to put in action back brake mechanisms, and liquid volume between the piston 17 and an end face of a stopper 20 — forward brake mechanisms.

When braking, moving forward, primary piston 10 and its cuff 15 block the compensation opening In connecting primary cavity of the main cylinder to a tank. The spring established between pistons 10 and 17 is stronger than the spring 19 located between the piston 17 and a stopper 20 therefore along with primary piston 10 also the secondary piston 17 begins to move, blocking a cuff a compensation opening And, connecting a secondary cavity of the cylinder to a tank. Further movement of pistons is followed by increase in pressure in cavities, and, therefore, both brake contours work.

At removal of effort from a brake pedal pistons under the influence of springs come back to initial situation. At the same time compensation openings open And yes In and liquid in both cavities of the main cylinder is reported with the liquid which is in a tank, pressure at the same time in contours decreases to atmospheric.

If the pedal of a brake is released sharply, then pistons of the main cylinder quickly come back to a starting position and at the same time are ready to the subsequent braking. Bystry return of pistons is provided that at their return to a starting position in cavities of the main cylinder depression under the influence of which liquid from a tank through perepuskny openings With and openings in pistons, wringing out washers 13 and edges of cuffs 14, comes to cavities of the main cylinder is created. When pistons reach the starting position, excess of liquid through compensation openings And yes In will flow from each cavity in a tank.

At failure of one of drive contours, there is a leak of liquid from the cavity of the main cylinder connected to a faulty contour. If the back contour is faulty, then the piston 10 reaches the holder of the 16th spring and through it influences the secondary piston 17 which creates pressure in a secondary cavity of the main cylinder and a forward contour.

At refusal of a contour of forward brake mechanisms the piston 17 influences an end face of a stopper 20, and the piston 10, squeezing a spring, forces out liquid from primary cavity of the main cylinder in the contour going to brake mechanisms of back wheels.

At refusal of one of contours of the drive there is an increase in the course of a pedal of a brake, but rather effective braking of the car is provided.

At serviceable contours the level of brake fluid has to be in a tank of the main cylinder between the marks MOVE and MIN. Gradual change of level of liquid from the MOVE to MIN is connected with wear of overlays of brake mechanisms. Sharp falling of level of brake fluid in a tank demonstrates violation of tightness of the brake system. At the same time the signaling device of emergency falling of level of brake fluid works and on a combination of devices the lamp of red color lights up. It is necessary to add liquid in this case only after restoration of tightness of system.

For check of serviceability of the sensor 6 of emergency falling of level of liquid in a tank it is necessary to press at the included ignition from above the central part of a protective cap 5. At the same time the lamp on a combination of devices has to light up.