6.8. Pressure regulator

Description of the device
The regulator of pressure corrects when braking pressure of brake fluid in back brake mechanisms, excepting a possibility of the advancing blocking of back wheels. It is reached by reduction of pressure in back brakes in relation to pressure in lobbies in proportion to load of a back axis.
The regulator is fixed on the bottom of a body and by means of a load spring reacts to change of the loading perceived by the back bridge.

Fig. 6.11. Pressure regulator: 1 – regulator case; 2 – piston spring; 3 – sealant; 4 – plug; 5 – the washer is lock; 6 – the washer is basic; 7 – pusher plug; 8 – the plate is basic; 9 – plug spring; 10 – the ring is sealing; 11 – valve saddle; 12 – laying; 13 – stopper; 14 – spring; 15 – valve; 16 – the ring is sealing; 17 – regulator pusher; 18 – the washer is basic; 19 – the ring is sealing; 20 – nut; 21 – piston plug; 22 – the ring is lock; 23 – the cover is protective; 24 – cap; 25 – regulator piston; 26 – arm


In the regulator four cameras: the camera A (fig. 6.11) connects to the second camera of the main brake cylinder, the camera F – to the first camera, the camera C – with left and the camera B – with right wheel cylinders of back brakes.

Fig. 6.12. Pressure regulator mechanism: 1 – pressure regulator; 2 – axis of the press lever; 3 – pin; 4 – the spring is load; 5 – the bolt is adjusting; 6 – nut; 7 – lever of press; 8 – screw; 9 – rack


In a starting position of a pedal of a brake the piston 25 is drawn in by the press lever 7 (fig. 6.12) through an adjusting bolt 5 to a pusher 17 (see fig. 6.11) which under the influence of effort is drawn in to a saddle of the 11th valve 15. At the same time the valve 15 is wrung out from a saddle therefore gaps of U and K between a head of the piston and a sealant 3 are formed. Through these gaps of the camera A and F are reported with cameras C and B. When pressing a brake pedal liquid through gaps To and U cameras C and B comes to wheel cylinders of back brake mechanisms. At increase in pressure of liquid the effort to the piston seeking to nominate him from the case increases. When the effort from pressure exceeds effort from the press lever, the piston begins to start from the case, and after it the 9 and 14 pusher 17 together with the plug 7 and rings 16 moves under the influence of springs.
At the same time the gap of N increases, and gaps of U and K decrease. When the gap of U is chosen completely and the valve 15 isolates the camera F from the camera B, the pusher 17 together with the details located on it will cease to move after the piston. Now pressure in the camera B will change depending on pressure in the camera C. At further increase in effort to a brake pedal pressure increases in the F, S and A cameras, the piston 25 continues to start from the case, and the plug 7 together with sealing rings 16 and a plate 8 under the amplifying pressure in the camera C moves towards a stopper 13. At the same time the gap of N begins to decrease. Due to reduction of volume of the camera In pressure in it, so, and in the drive of a brake accrues and it will be almost equal to pressure in the camera C. When the gap To is completely chosen, pressure in the camera C, so, and in the camera B will grow to a lesser extent, than pressure in the camera A, at the expense of a liquid drosselirovaniye between a head of the piston and a sealant 3. Dependence between pressure in cameras C and A is defined by the relation of a difference of the areas of a head and a rod of the piston to the area of a head. In the case of 1 regulator the opening closed by a cap 24 is executed. The liquid leak from under a cap at its expression testifies to leakage of rings 16.

Check and preliminary adjustment of the regulator of pressure
Accelerate the car to the speed of 50-60 km/h on the flat horizontal section of the road with a hard dry coating. Then you brake, smoothly increasing efforts to a brake pedal before blocking of wheels. The observer who is out of the car has to fix some advancing of blocking of forward wheels.
At earlier blocking of back wheels, holding from a provorachivaniye an adjusting bolt 5 (see fig. 6.12), turn off a lock-nut 6, then turn counterclockwise on 1/2 turns an adjusting bolt and tighten a lock-nut, without allowing rotation of an adjusting bolt. Repeat trial arrival. At too late blocking of back wheels rotate an adjusting bolt clockwise.
If in this way it is not possible to achieve normal operation of the regulator, remove it from the car and check at the stand. If necessary repair or replace the regulator.

Removal and installation of the regulator of pressure
1. Disconnect a rack of the 9th load spring 4 from an arm on a beam of the back bridge, having removed a spring washer and having taken out an axis of the lower hinge from an opening in an arm.
2. Disconnect pipelines from the regulator. Mark them that at installation to attach to the same nests. Muffle openings of pipelines.
3. Turn off three nuts of fastening of an arm of the regulator to the bottom of a body and remove the regulator.
4. Install pressure regulator upside-down. After that restore liquid level in a tank and pump over a hydraulic actuator.

Check of the regulator of pressure at the special stand
Remove pressure regulator from the car and install it on the stand. Give to entrance openings brake fluid with pressure not less than 3 MPas (30 kgfs/cm2) and apply to the end of a rack of the 9th load spring the 4th effort of 10 N (1 kgf) in the direction of an arrow A. Pressure at the exit has to be twice less than pressure on an entrance. Keeping the given pressure at the certain level, increase load of a load spring. If pressure at the exit begins to increase – the regulator is serviceable.

Repair of the regulator of pressure
1. Turn out the screw 8 (see fig. 6.12) fastenings of a spring, take out a persistent pin 3 and release the end of a load spring 4.
2. Take out axis 2 and remove press the lever 7. When dismantling the regulator it is not necessary to violate the provision of an adjusting bolt 5.
3. Remove a protective cover 23 (see fig. 6.11).
4. Having turned off a nut 20, disconnect from the regulator an arm 26.
5. Turn out a stopper 13, remove laying 12, take out a spring 9 and a basic plate 8.
6. Press on the plug of 21 pistons and remove a lock ring 22. At the same time hold the plug until due to effort of a spring 2 it do not go out of the case, remove it.
7. Take out the piston 25 with sealants 3 and 19, washers 18 and a spring 2.
8. Take out a pusher 17 with sealing rings 16, the plug 7 and a washer 6. If necessary take out the plug 4 from the case.
9. Wash out details pure brake fluid, attentively examine them. Surfaces of details should not have damages and noticeable wear.
10. Check a state and elasticity of a spring 9. Its length in a free state has to be 14 mm, under load (15±1,5) N or (1,5±0,15) kgfs – 7,5 mm.
11. Check at the special stand tightness of the valve 15, zavaltsovanny in a stopper 13. In case of leak of liquid when checking (the ring 10 is damaged) replace a stopper assembled with the valve.
12. Check a cylinder mirror. Existence рисок and blackouts is not allowed.
13. Replace the damaged and worn-out details, and also sealing rings new.
14. Plentifully grease sealing rings, the piston with a pusher and a cylinder mirror pure brake fluid.
15. Install the plug 4 if it was taken out in the case.
16. Collect the piston 25 together with sealants 3 and 19, washers 18, a spring 2, the plug 21 and insert into the case of 1 regulator.
17. Press on the plug 21 and insert a lock ring 22.
18. Collect a pusher 17 with a washer 6, sealing rings 16, the plug 7, a basic plate 8 and insert into the regulator case.
19. Establish a spring 9, laying 12 and wrap a stopper the 13th moment of 40-50 N · m (4–5 kgfs · м).
20. Be convinced available caps 24, in case of absence – insert new.
21. Collect the regulator with an arm 26, having wrapped a nut the 20th moment of 40-50 N · m (4–5 kgfs · l), put on a protective cover 23.
22. Insert into an arm press the lever 7 (see fig. 6.12), axis 2, a load spring 4, a pin 3. Fix an arm by the screw 8 the moment of 9 - 12 N · m (0,9–1,2 kgfs · м).