The design of a support has one wheel brake cylinder and fastens on a rotary fist two bolts. When pressing a brake pedal the created hydraulic pressure will be transformed by a support to the braking effort. This effort is transferred equally to the piston and to a support cylinder bottom, moving the piston and shifting a support. It brings to a zazhatiya of a brake disk on both sides.

Fig. 12.17. Support of disk brakes and brake disk: 1 – external brake shoe; 2 – spring; 3 – internal brake shoe; 4 – bolt of fastening of the case of a support; 5 – a washer of the directing finger; 6 – cap; 7 – the directing finger; 8 – protective cover; 9 – a support with the brake cylinder; 10 – support plug; 11 – sealing ring of the piston; 12 – piston; 13 – protective cap of the piston; 14 – guide of blocks; 15 – fingers; 16 – brake board; 17 – wheel nave; 18 – brake disk; 19 – forelock; 20 – nut of fastening of the hug bearing; 21 – persistent washer; 22 – screw; 23 – screw of fastening of a brake board; 24 – washer

The squeezing effort is transmitted through overlays of brake shoes. Friction force arising at the same time leads to a car stop.

       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. 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 of 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.

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 cylinder have to be performed on a pure dry workbench.

1. Pump out two thirds of brake fluid from a tank.

2. Lift the car on the elevator.

3. Note provisions of disks of forward wheels in relation to naves and remove wheels.

       PREVENTION

For replacement of brake shoes or service of a brake disk it is not required to remove a support.

Fig. 12.18. Knocking-out of fingers: 1 – support; 2 – brake shoe; 3 – fingers; 4 – drift; 5 – hammer; 6 – guide of blocks

4. Beat out fingers 3 (fig. 12.18) brake shoes from the inside of a nave.

       PREVENTION

Springs under the influence of fingers are in the compressed state. Be careful.

5. Big flat-nose pliers press the piston in the support cylinder. It will create a gap between brake shoes and a brake disk.

6. Remove brake shoes with slips. Now it is possible to remove a brake disk without removal of a support.

Measure thickness of a brake disk.

Check a condition of a surface of a brake disk.

Check a condition of a dustproof cap of the piston.

1. Establish a brake shoe with the wear sensor to the support piston. At installation check a possibility of small movements of brake shoes in a support forward/back.

2. Establish a spring on a brake shoe.

Fig. 12.19. Installation of fingers (1) and springs (2)

3. Establish fingers from outer side of a support inside, previously having leveled an arrangement of openings (fig. 12.19).

4. Establish wheels, having combined the marks made earlier.

5. Lower the car.

6. Several times press a brake pedal to bring blocks into contact with brake disks.

       PREVENTION

Do not move the car until the pedal of a brake does not become rigid when pressing.

7. Check the level of brake fluid and if necessary add it.

Fig. 12.20. Reversing of a guide of blocks: 1 – support; 2 – guide of blocks; 3 – key

1. Turn off and remove a guide of blocks from a support (fig. 12.20).

2. Turn out the screw and remove a brake disk.

Fig. 12.21. Removal of a protective cap: 1 – nave; 2 – protective cap; 3 – chisel

3. By means of a chisel 3 (fig. 12.21) get moving forward a protective cap 2 and the screw-driver remove it from a support 1.

1. Dress a protective cap on a pro-point in the piston and insert into the wheel brake cylinder. If it is necessary, for installation of a dustproof cap in the cylinder slightly wring out the piston from the wheel cylinder.

2. Establish a dustproof cap into place.

3. Establish a brake disk and fix it.

4. Screw guides of blocks on a support and tighten their moment 95 N • m.

       PREVENTION

For removal of a brake disk it is not required to remove a support.

1. Remove brake shoes.

2. Turn out the adjusting screw of fastening of a brake disk.

Fig. 12.22. Removal of a brake disk

3. Remove a brake disk (fig. 12.22). Incline a brake disk a little and remove it. If it is required, pull a little for a support in the direction outside.

1. Establish a brake disk and fix it by the adjusting screw.

       PREVENTION

For ensuring identical braking of both wheels of a surface of their brake disks have to be identical. It concerns smoothness of a surface and depth of the available scratches. Therefore if necessary replace both brake disks at the same time.

2. Establish brake shoes.

1. Pump out two thirds of brake fluid from a tank.

2. Lift the car on the elevator.

3. Note provisions of disks of forward wheels in relation to naves and remove wheels.

4. Big flat-nose pliers press the piston in the support cylinder. It will create a gap between brake shoes and a brake disk.

5. If for repair it is necessary to remove a support from the car, turn off hollow perepuskny a bolt, the fixing brake hose to a support. For prevention of an effluence and pollution of brake fluid close the opened openings in a hose and a support.

Fig. 12.23. Use of a chisel (1) for removal of protective caps (2) from a support

6. By means of a chisel 1 (fig. 12.23) shift a protective cap 2 from a support and finally remove it by means of the screw-driver.

7. Turn out bolts of fastening and remove a support from a rotary fist.

If removal of a support is necessary only for ensuring access to other knots, suspend it on a soft wire on a rack of a forward suspension bracket.

At production the carving of bolts of fastening of a support was processed by the blocking means interfering their otvorachivaniye.

Clean a carving in rotary fists a tap of M 12x1,5.

If the carving of new bolts of fastening of a support was not processed by the blocking means interfering their otvorachivaniye put the blocking means.

Fig. 12.24. Tightening of bolts of fastening of a support: 1 – bolts, 95 N • m; 2 – key

1. Establish a support on a rotary fist, fix by bolts 1 (fig. 12.24) and tighten their moment 95 N • m.

2. Fix a brake hose by a hollow perepuskny bolt and tighten its moment 25 N • m.

3. Establish protective caps from the outer side of a support.

       PREVENTION

Always use new protective caps. Protective caps have to adjoin to the support case evenly on all surface.

4. Establish wheels, having combined earlier made marks, and tighten bolts of fastening of wheels.

5. Lower the car.

6. Add in a tank pure brake liquid to the required level. If brake hoses were disconnected, then pump over the wheel brake cylinder.

7. Several times press and release a brake pedal to bring blocks into contact with a brake disk.

1. Remove a support.

2. Turn out the adjusting screw and remove a brake disk.

3. Through an opening in a nave turn out bolts of fastening of a brake board.

Fig. 12.25. Removal of a brake board: 1 – brake board; 2 – wheel nave

4. Turn a brake board so that access to the thin crossing point connecting two half of a board opened and scissor it on metal (fig. 12.25).

5. Remove a brake board through a wheel nave neck.

Fig. 12.26. Preparation of a new brake board

1. Before installation of a new brake board cut out scissors on metal a connecting crossing point (fig. 12.26). Clear the cut edge of agnails and coat.

2. Dress a brake board with the cut-out crossing point through a neck of a nave of a wheel and attach to a rotary fist.

3. Establish a brake disk and screw the adjusting screw.

4. Establish a support.

1. Remove a support.

2. Remove brake shoes from a support.

Fig. 12.27. Removal of protective caps from the inside of a support: 1 – vice; 2 – support; 3 – screw-driver; 4 – protective cap

3. By means of the screw-driver remove protective caps of the directing fingers from the inside of a support (fig. 12.27).

Fig. 12.28. Use of a chisel for removal of a dustproof cap from a support: 1 – support; 2 – dustproof cap; 3 – chisel

4. By means of a chisel remove a dustproof cap of the piston from the wheel cylinder (fig. 12.28).

5. Press the plug outside in the direction of a protective cap and remove a protective cap from a pro-point on the surface of the plug.

6. Remove a dustproof cap from the piston and the wheel cylinder.

Fig. 12.29. Removal of plugs of sliding: 1 – plug; 2 – sealing ring

7. Squeeze out plugs 1 (fig. 12.29) from the case of the wheel cylinder and take out sealing rings 2 by means of the wooden or plastic tool.

Fig. 12.30. Removal of the piston: 1 – guide of blocks; 2 – board; 3 – piston; 4 – vice; 5 – support; 6 – supply of compressed air

8. Remove the piston from a support, giving to the cylinder compressed air through an opening for connection of a brake hose (fig. 12.30).

       PREVENTION

At supply of compressed air do not try to hold a hand in front of the piston in order that to catch it, it can lead to a serious trauma. At extraction of the piston insert a wooden board 15-20 mm thick in the support case.

Fig. 12.31. Use of a key (3) fastenings of a guide of blocks (1) to a support (2)

9. Turn off a guide of blocks from a support and remove it (fig. 12.31). For simplification of dismantling clamp a support in a vice.

Fig. 12.32. Extraction of a sealing ring of the wheel cylinder: 1 – vice; 2 – support; 3 – sealing ring; 4 – wooden or plastic tool

10. By means of the small wooden or plastic tool get a sealing ring 3 (fig. 12.32) from a flute in the wheel cylinder. Do not use for this purpose the metal tool as these can damage the internal surface of the wheel cylinder or a flute.

11. Turn out the union.

Clear all details pure brake fluid or denatured alcohol.

Dry all details the air from the compressor which is not containing vapors of oils.

Blow all channels in the case and in unions.

Check the piston and the wheel cylinder for existence:

– scratches;

– jags;

– corrosion.

Replace details at detection of the specified defects.

If one of details rusted, replace a support and the piston assembled.

       PREVENTION

Grinding of the piston or cylinder of a support is not allowed.

1. Insert the greased sealing ring of the piston into a support cylinder flute. Make sure that the ring is not overwound.

Fig. 12.33. Installation of the piston

2. Install the piston greased with brake fluid in the support cylinder (fig. 12.33). At installation of the piston be convinced that it is inserted without distortion and that the sealing ring in a flute of the cylinder is established correctly.

Not to utaplivayta the piston in a cavity of the wheel cylinder completely. Leave the piston acting so that in a flute on the piston it was possible to establish a dustproof cap.

3. Establish a dustproof cap in a flute on the piston and push the piston in the support cylinder.

4. Put on a cap edge of the cylinder of a support.

5. Establish a guide of blocks and fix by bolts to a support, having tightened their moment 95 N • m.

6. Install sealing rings on the sliding plugs.

Cover plugs with a thin layer of the dense lubricant delivered in repair set.

Establish a sealing ring in the central flute of the sliding plug. Make sure that the sealing ring did not warp at installation in a flute.

7. Install the sliding plug in a support so that the flute for an internal protective cap settled down from the same party of the cylinder, as the piston. Move the plug back and forth.

Leave the end of the plug acting so that it was possible to put on a protective cap it.

8. Establish internal protective caps in flutes of the sliding plugs and dress on a side on the support cylinder case.

9. Establish protective caps into place.

       PREVENTION

Always establish new protective caps.

10. Drown the sliding plugs in the support cylinder case.

11. Screw the directing fingers.

12. Establish a brake shoe with the wear sensor from the piston.

       PREVENTION

Make sure that fingers and springs are established correctly.

13. Establish a support.

Bolt of a guide of blocks to a support......... 95 N • m

Bolt of fastening of a support to a rotary fist........ 95 N • m

Hollow perepuskny bolt of fastening of a brake hose........ 25 N • m