Fig. 8.3. The main brake cylinder: 1 — the case; 2 — a tube; 3 — the connecting plug; 4 — a tank; 5 — a protective cap; 6 — the gauge of a signalling device of emergency falling of level of a brake liquid; 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 — compensatory apertures; With — перепускные apertures

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

The main brake cylinder creates pressure in two independent hydraulic contours. The volume of a brake liquid 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.

At braking, moving forward, the primary piston 10 and its cuff 15 block a compensatory aperture In, connecting a primary cavity of the main cylinder with a tank. The spring established between pistons 10 and 17, is stronger than a spring 19 located between the piston 17 and stopper 20, therefore simultaneously with the primary piston 10 starts to move and the secondary piston 17, blocking a cuff a compensatory aperture And, connecting a secondary cavity of the cylinder with a tank. The further moving of pistons is accompanied by pressure increase in cavities, and, hence, work both brake contours.

At removal of effort from a pedal of a brake pistons under the influence of springs come back in initial position. Compensatory apertures And and thus open In and the liquid in both cavities of the main cylinder is informed with a liquid which is in a tank, pressure thus in contours decreases to the atmospheric.

If the brake pedal is released sharply pistons of the main cylinder quickly come back in a starting position and are thus ready to the subsequent braking. Fast return of pistons is provided with that at their returning in a starting position in cavities of the main cylinder depression under which action a liquid from a tank through перепускные apertures With and apertures in pistons, wringing out washers 13 and edges of cuffs 14 is created, arrives in a cavity of the main cylinder. When pistons will reach the starting position, surplus of a liquid through compensatory apertures And and In will flow from each cavity in a tank.

At failure of one of drive contours, there is a leak of a liquid from the cavity of the main cylinder connected to a faulty contour. If the back contour the piston 10 reaches the holder of 16 springs is faulty 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, compressing a spring, supersedes a liquid from a primary cavity of the main cylinder in a contour going to brake mechanisms of back wheels.

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

At serviceable contours level of a brake liquid should be in a tank of the main cylinder between marks the MOVE and MIN. Gradual change of level of a liquid from the MOVE to MIN is connected with deterioration of overlays of brake mechanisms. Sharp falling of level of a brake liquid in a tank testifies to infringement of tightness of brake system. Thus works a signalling device of emergency falling of level of a brake liquid and on a combination of devices the lamp of red colour lights up. To add a liquid in this case follows only after restoration of tightness of system.

For check of serviceability of the gauge 6 emergency falling of level of a liquid in a tank are necessary for pressing at the included ignition from above the central part of a protective cap 5. The lamp on a combination of devices Thus should light up.