Fig. 12.9. Main brake cylinder: 1 – cover of a tank of brake fluid; 2 – tank of brake fluid; 3 – sealing rings of a tank; 4 – tank clips; 5 – case of the main brake cylinder; 6 – proportional valves; 7 – knot of the piston of the second contour; 8 – piston of the first contour; 9 – lock ring of the piston; 10 – sealing ring

The main brake cylinder is intended for use in the brake system with diagonal division of contours (one forward brake and the back brake located on diagonal from it works from the first piston, and the second forward brake and diagonalno the located back brake – from the second piston) (fig. 12.9). Except two pistons, the main cylinder is equipped with the sensor of level of brake fluid and proportional valves for adjustment of pressure.

For simplification of process of assembly grease all rubber details with pure brake fluid.

Do not blow a detail of the brake system the air from the compressor containing vapors of oils. It can lead to damage of rubber details and knots.

When dismantling knots of the hydraulic drive of the brake system there can be a need of pumping of all brake system or its part.

       PREVENTION

At repair of the main brake cylinder it is necessary to replace all details included in a repair set of spare details of the main brake cylinder.

Values of the moments of an inhaling of fasteners are given for the dry, not greased carving surfaces.

Operations on service of details of the main brake cylinder have to be performed on a pure dry workbench without danger to pollute details mineral oils.

1. Disconnect the socket of the sensor of emergency level from a tank cover.

2. Pump out brake fluid from a tank.

Fig. 12.10. Removal of a tank for brake fluid: 1 – tank; 2 – main brake cylinder; 3 – screw-driver

3. The screw-driver 3 (fig. 12.10) wring out springs of clips down. Incline a tank and remove it up.

4. Remove sealing rings of a tank from the case of the main brake cylinder 2.

1. Grease new sealing rings with pure brake fluid and install them in the case of the main brake cylinder.

Fig. 12.11. Installation on a tank (1) of new collars (2)

2. Establish new collars on a tank (fig. 12.11).

3. Install a tank on the case of the main brake cylinder.

4. Pump over the brake system.

5. Connect the electric socket of the sensor.

Replace a cover of a tank of brake fluid with a tight cap that in the dashboard the control lamp of low level of brake fluid did not burn.

       PREVENTION

At the correct installation of a tank the click has to be into place heard.

1. Disconnect the pipeline of the brake system from proportional valves.

2. Remove valves from the main brake cylinder.

       PREVENTION

As these valves are adjusted in common, it is necessary to replace at once both valves.

1. Screw valves in the case of the main brake cylinder and tighten their moment 40 N • m.

       PREVENTION

Fig. 12.12. Designation of proportional valves

Fig. 12.13. Removal of a sealing ring: 1 – screw-driver; 2 – sealing ring

Before installation of valves be convinced that both valves have identical marking from two numbers as it is shown in fig. 12.13.

2. Connect brake pipelines to valves and tighten connecting nuts the moment of 11 N • m.

3. Pump over brakes.

4. Check for existence of leak of brake fluid.

5. Check the level of brake fluid in a tank.

6. Remove a tight cap from a tank and establish a tank cover for brake fluid.

1. Disconnect the socket of the sensor of emergency level from a tank cover.

2. Disconnect brake pipelines from the case of the main brake cylinder and proportional valves. To prevent an effluence or pollution of brake fluid, close plastic caps the open ends of brake pipelines.

3. Turn out two fixing nuts.

4. Remove the main brake cylinder.

1. Install the main brake cylinder, fix new самоконтрящимися by nuts and tighten their moment 18 N • m.

2. Connect brake pipelines to proportional valves of the case of the main brake cylinder and tighten connecting nuts the moment of 11 N • m.

3. Connect the electric socket of the sensor.

4. Add brake fluid in a tank.

5. Pump over brakes.

6. Double-check the level of brake fluid.

The compressed air given from the compressor drain the main brake cylinder.

1. Remove the main brake cylinder.

2. Clamp the main brake cylinder in a vice and remove a tank.

3. Get a sealing ring from the case of the main brake cylinder (fig. 12.13).

Fig. 12.14. Cave-in of pistons in the main brake cylinder: 1 – wooden or plastic drift; 2 – main brake cylinder; 3 – welding electrode with a diameter of 3 mm

Fig. 12.15. Extraction of a lock ring: 1 – lock ring; 2 – screw-driver; 3 – welding electrode with a diameter of 3 mm

4. By means of a suitable wooden or plastic drift 1 (fig. 12.14) press pistons approximately on 10 mm in the cylinder. To hold cylinders in the pressed situation, insert into a compensation opening a welding electrode with a diameter of 3 mm or something similar.

Fig. 12.16. Extraction of the second piston: 1 – second piston; 2 – compressed air

5. By means of the suitable screw-driver take a lock ring 1 (fig. 12.16) from the case of the main brake cylinder.

       PREVENTION

Do not damage walls of the main brake cylinder or the surface of the piston. The lock ring is not subject to reuse.

6. Press pistons by means of a wooden/plastic drift in the cylinder and take an electrode from a compensation opening.

7. Get the first piston from the case of the main brake cylinder. For this purpose knock with the cylinder about a wooden surface until the piston is able to be taken.

8. Get the second piston 1 (fig. 12.16) from the cylinder case. Accurately take the second piston by means of the compressed air given from the compressor.

9. Wash out and clear all details by means of pure brake fluid or denatured alcohol.

       PREVENTION

Check the internal surface of the main brake cylinder regarding scratches and corrosion. At detection – replace the main brake cylinder.

Processing of an internal surface of the main cylinder abrasive materials is not allowed.

       PREVENTION

After dismantling repeated installation of rubber details and sealing rings of the main brake cylinder is not allowed.

1. Grease the internal surface of the main brake cylinder with pure brake fluid.

2. Clamp the case of the main brake cylinder in a vice openings for a tank up.

3. Accurately insert the second piston in the main brake cylinder and push against the stop in the cylinder case basis. As the tool use a wooden/plastic drift.

4. Insert the first piston.

Press pistons and insert a welding electrode or a similar subject into a compensation opening to hold pistons in this situation at installation of a lock ring.

5. Establish a lock ring in a flute on the internal surface of the cylinder.

       PREVENTION

Do not damage the internal surface of the cylinder.

6. By means of a wooden/plastic drift press pistons and get a welding electrode.

7. After installation move pistons for check of their free movement back/forward.

8. Grease with brake fluid a sealing ring and insert it into a cylinder opening the open party outside before landing of a ring to the piston.

9. Install the main brake cylinder into place.

10. Pump over brakes.

Proportional valves......... 40 N • m

Brake pipelines........ 11 N • m

Nuts of fastening of the main brake cylinder........ 18 N • m