Fig. 12.39. Vacuum amplifier of brakes: 1 – nut of fastening of the main brake cylinder; 2 – main brake cylinder; 3 – backpressure valve of the vacuum amplifier of brakes; 4 – hose of the vacuum amplifier of brakes; 5 – sealing ring of a hose; 6 – vacuum amplifier of brakes; 7 – plug of the device of adjustment of the course of a pedal of a brake; 8 – lock plate of the device of adjustment of the course; 9 – nut; 10 – brake pedal pusher; 11 – protective cover; 12 – bracket of fastening of the vacuum amplifier of brakes

The vacuum amplifier of brakes reduces the effort enclosed to a brake pedal, facilitating thereby driving (fig. 12.39). The principle of operation of the vacuum amplifier of brakes is based on use of depression in an inlet collector. At an exit of the vacuum amplifier out of operation operability of the brake system is not broken, but for pressing of a pedal of a brake it is necessary to make considerably bigger effort.

       PREVENTION

At removal or a detachment of details of the hydraulic drive there can be a need of pumping of the brake system in general or its separate knots.

The specified moments of inhalings of threaded connections are given for the dry, not greased surfaces.

1. By means of nippers cut a collar of fastening of a vacuum hose and remove a vacuum hose from an inlet collector.

Fig. 12.40. Arrangement of a vacuum hose

2. Remove a vacuum hose and a connecting detail from the case of the vacuum amplifier of brakes (fig. 12.40).

3. Measure length of the replaced vacuum hose.

4. Cut off a vacuum hose on both sides of the backpressure valve 3 (see fig. 12.39).

       PREVENTION

At the choice of a vacuum hose from a set of spare parts the vacuum hose has to have the same diameter, and new fixing collars have to be established in all points of fastening.

1. Cut off a new vacuum hose of the corresponding length and establish, having put on collars.

2. Fix collars and be convinced that connections dense.

       PREVENTION

Make sure that the vacuum backpressure valve is installed in the same direction, as replaced.

3. Check operation of the vacuum amplifier of brakes.

1. Press a brake pedal several times at the idle engine to create the identical pressure close to atmospheric in cavities of the vacuum amplifier. At the same time, determine by the effort enclosed to a pedal whether there is no jamming of the case of the valve. Stop a brake pedal in the middle of its course and launch the engine.

2. At the serviceable vacuum amplifier the brake pedal after start of the engine has to leave forward.

3. If the pedal does not leave forward, check fastening of a tip of a hose, connection of fastening of a flange of a tip in the amplifier, a condition of a hose and the union.

4. If when checking defects it is not revealed, so the vacuum amplifier of brakes is faulty.

1. Remove the main brake cylinder from the vacuum amplifier of brakes and remove a little forward. Do not disconnect brake pipelines.

2. Remove a vacuum hose from the amplifier.

3. Remove a windshield washer reservoir.

4. Remove the stoplight sensor.

5. Remove a brake pedal spring.

6. Remove a lock bracket of a finger of a pusher and a finger of a pusher.

7. Unscrew the lower screw located behind the brake pedal pipeline.

8. Remove the amplifier with an assembly bracket of the panel, having a little inclined and having removed the drive up.

9. Remove a fixing bracket from the amplifier.

10. Remove a protective cover 11 (see fig. 12.39) from the amplifier.

Fig. 12.41. Removal of a lock plate: 1 – plug of the adjusting device; 2 – lock plate; 3 – screw-driver

11. Remove a lock plate 2 from a pusher and the plug of the adjusting device 1 (fig. 12.41).

12. Remove a pusher 10 (see fig. 12.39).

Fig. 12.42. Removal of the plug of the adjusting device

13. Turn off and remove the plug of the adjusting device from a piston rod (fig. 12.42).

14. Turn off a nut 9 (see fig. 12.39).

1. Clamp the new vacuum amplifier in a vice, at the same time use safety overlays for sponges of a vice.

2. Wrap a nut 9 and the adjusting plug 7 on a piston rod.

3. Insert a pusher 10 into the plug 7 and fix a lock plate 8.

Fig. 12.43. Measurement of length (A) of a pusher: 1 – pusher; 2 – vacuum amplifier of brakes; In – the center of an opening

Adjust position of the plug. The distance from the surface of the amplifier to the center of an opening under a finger in a fork of a pusher has to be 278,5 mm (fig. 12.43).

4. Establish a protective cover 11 (see fig. 12.39) on the amplifier.

5. Establish a fixing bracket to the amplifier and fix by bolts, having tightened their moment 22 N • m.

6. Establish the amplifier with a bracket on a partition of a motor compartment.

7. Install a windshield washer reservoir.

8. Install the main brake cylinder on the amplifier and fix by nuts, having tightened their moment 18 N • m.

9. Connect a vacuum hose to the amplifier and screw a connecting nut on an inlet collector, having tightened its moment 15 N • m.

10. Implant a finger of connection of a pusher and pedal of a brake.

11. Establish a lock bracket and connect a pedal spring.

12. Install the stoplight switch.

Nut of fastening of the main brake cylinder to the amplifier........ 18 N • m

Connecting nut and vacuum hose to an inlet collector........ 15 N • m

Nut of fastening of an assembly bracket to the amplifier........ 22 N • m

Nut of fastening of an assembly bracket to a partition of a motor compartment........ 22 N • m