6.4. Main brake cylinder

Features of a design

Fig. 6.2. The main brake cylinder with the vacuum amplifier: 1 – case cover; 2 – connecting ring; 3 – diaphragm; 4 – case basis; 5 – basic ring of a diaphragm; 6 – basic plate of a disk; 7 – sector of a basic disk of a diaphragm; 8 – the fixing washer of sectors; 9 – central valve; 10 – the directing piston ring; 11 – sealing cuff of the case of the piston; 12 – lock washer of a sealing cuff; 13 – piston case; 14 – clamping plug of a support of a pusher; 15 – air filter; 16 – piston pusher; 17 – adjusting screw; 18 – piston emphasis; 19 – locking ring of a diaphragm; 20 – returnable spring of the piston; 21 – persistent bracket; 22 – rod of the amplifier; 23 – returnable spring of sectors; 24 – adjusting bolt; 25 – backpressure valve; 26 – tank of the main cylinder; 27 – tank cover; 28 – tube of the connecting plug; 29 – connecting plug; 30 – persistent pin; 31 – piston of the second camera; 32 – returnable spring of the piston of the second camera; 33 – persistent washer of a cuff; 34 – main cuff; 35 – piston valve; 36 – case of the main cylinder; 37-dividing cuff of cameras of the main cylinder; 38 – returnable spring of the piston of the first camera; 39 – piston of the first camera; 40 – sealing ring; 41 - cap; And – the first camera; In – the second camera; With – a compensation opening


The main cylinder of the hydraulic drive of brakes like "tandem" has two separate cameras connected to independent hydraulic contours. The first camera A (fig. 6.2) is connected with left forward and right back brakes, the second In – with right forward and left back.
Has the main cylinder the tank 26, an internal cavity of which a partition is divided into two compartments. Each compartment feeds one of cameras of the main cylinder.
For an exception of cases of increase in pressure in contours because of temperature expansion of liquid each camera is reported with the feeding tank through a compensation opening of Page.
By pressing a brake pedal pistons of the main cylinder begin to move, working edges of cuffs block compensation openings, cameras and a tank are separated and replacement of brake fluid begins.

Removal and installation of the main brake cylinder
1. Clear of dirt the main cylinder, the vacuum amplifier and pipelines departing from the main cylinder.
2. Disconnect pipelines from the main cylinder. Muffle openings of tubes.
3. Turn off two nuts of fastening of the main cylinder to the vacuum amplifier and remove the cylinder from hairpins.
4. Uncover a tank and merge from it brake fluid.
5. Remove the remains of brake fluid from the main cylinder, having turned the main cylinder a tank down and having pressed several times the piston 39 of the first camera.
6. Before installation of the main cylinder on the vacuum amplifier check a condition of a sealing ring 40. Replace the ring torn or lost elasticity.
7. Install the main cylinder upside-down, fill in brake fluid and pump over a hydraulic system.
Repair of the main brake cylinder
1. Remove the main cylinder from the car.
2. Using a wooden shovel as the lever, remove a tank 26 from the cylinder.
3. Take connecting plugs 29 from the case of the main cylinder.
4. Having pressed the piston 39 of the first camera, take flat-nose pliers with narrow and thin sponges a persistent pin of the 30th piston of the second camera.
5. Remove the cap 41 holding the piston of the first camera from the case.
6. By effort of a hand take from the case pistons of the first and second cameras with cuffs, washers and springs. If the piston of 31 second cameras with the remained details is not taken out easily, blows of an end face of the case from the first camera about a pure board advance it via the first camera. For extraction of the piston it is also possible to use compressed air which needs to be brought to an exhaust outlet of the second camera, having closed at the same time an opening under a tank.
7. Attentively examine and are convinced of ideal purity of a mirror of the cylinder and the working surface of pistons, lack of a rust, рисок and other roughnesses.
8. Defects on a mirror of the case are eliminated with a honingovaniye, at the same time the internal diameter of the cylinder should not exceed 21,081 mm. Otherwise replace the case new.
9. Replace the cuffs torn, inflated or lost elasticity. It is recommended to replace at each dismantling of the main cylinder cuffs new irrespective of their state.
10. Replace the springs of pistons which lost elasticity.
11. Before assembly wash out all details pure brake fluid. Hit on a detail of mineral oils, gasoline, kerosene or diesel fuel is not allowed: even residual traces of these liquids can lead to destruction of rubber cuffs.
12. Install valves on pistons. Then establish cuffs, having oriented their working edges, as shown in fig. 6.2. For simplification of installation of cuffs it is recommended to moisten them with weak soap solution.
13. Install on plate pistons of springs. Then install a returnable spring on the piston of the second camera and connect a returnable spring both pistons. For simplification of installation of a spring screw on shafts of pistons.
14. Plentifully grease a mirror of the main cylinder and pistons with cuffs fresh brake fluid and insert pistons into the case of the main cylinder. For simplification of installation it is possible to fill accurately with a blunt object working edges of cuffs through openings in lugs under fastening of a tank.
15. Press a shaft of the piston of the first camera and establish a persistent pin 30.
16. Install on the case a cap 41.
17. Install connecting plugs of a tank on the case, previously having greased them with fresh brake fluid.
18. Put on a tank connecting plugs.