8.3. Pressure regulator drive: A, B, C - holes; 1 - pressure regulator; 2, 16 - pressure regulator mounting bolts; 3 - arm of the pressure regulator drive lever; 4 - pin; 5 - pressure regulator drive lever; 6 - axis of the pressure regulator drive lever; 7 – lever spring; 8 - body bracket; 9 - pressure regulator mounting bracket; 10 - elastic lever of the pressure regulator drive; 11 - earring; 12 – earring bracket; 13 - washer; 14 - retaining ring; 15 - bracket pin
Pressure regulator 1 (pic. 8.3) is attached to the bracket 9 with two bolts 2 and 16. The fork bracket 3 of the lever 5 of the pressure regulator drive is simultaneously attached to the front bolt 2. On the pin of this bracket, a two-arm lever 5 is pivotally fixed with a pin 4. Its upper arm is connected to an elastic lever 10, the other end of which is pivotally connected through an earring 11 to the rear suspension arm bracket. The bracket 3 together with the lever 5 can be moved relative to the pressure regulator due to the oval holes for the fastening bolt. This regulates the force with which the lever 5 acts on the regulator piston (see «Pressure Regulator Actuator Adjustment»).
8.4. Pressure regulator: A, D - chambers connected to the main cylinder; B, C - chambers connected to the wheel cylinders of the rear brakes; E - control hole; K, M, H - gaps; 1 - pressure regulator housing; 2 - piston; 3 - protective cap; 4, 8 - retaining rings; 5 - piston sleeve; 6 - piston spring; 7 - housing sleeve; 9, 22 - support washers; 10 - pusher sealing rings; 11 - support plate; 12 - pusher bushing spring; 13 - sealing ring of the valve seat; 14 - valve seat; 15 - sealing gasket; 16 - cork; 17 - valve spring; 18 - valve; 19 - pusher bushing; 20 - pusher; 21 - piston head seal; 23 - piston rod seal; 24 - plug
The regulator has four chambers: A and D (pic. 8.4) connected to the master cylinder, B - to the right, and C - to the left working cylinder of the rear brakes.
In the initial position of the brake pedal, piston 2 is pressed by lever 5 (see fig. 8.3) through the leaf spring 7 to the pusher 20 (see fig. 8.4), which is pressed against the seat 14 of the valve 18 by this force. The latter is pressed from the seat, a gap H and a gap K are formed between the piston head and the seal 21. Through these gaps, chambers A and D communicate with chambers B and C.
When you press the brake pedal, the fluid through the gaps K and H and chambers B and C enters the wheel cylinders of the brake mechanisms. With an increase in fluid pressure, the force on the piston increases, tending to push it out of the housing. If the force from the fluid pressure exceeds the force from the elastic lever, the piston begins to move out of the housing, and after it the pusher 20 moves under the action of the springs 12 and 17 together with the sleeve 19 and rings 10. The gap M increases, and the gaps H and K decrease. When gap H is fully selected and valve 18 isolates chamber D from chamber C, pusher 20, together with the parts located on it, will stop moving after the piston. Now the pressure in chamber C will change depending on the pressure in chamber B. With a further increase in the effort on the brake pedal, the pressure in chambers D, B and A increases, piston 2 continues to move out of the housing, and sleeve 19, together with o-rings 10 and plate 11 under increasing pressure in chamber B, it shifts towards plug 16. Gap M begins to decrease. By reducing the volume of chamber C, the pressure in it, and hence in the brake drive, increases and will practically be equal to the pressure in chamber B. When the gap K becomes zero, the pressure in chamber B, and hence in chamber C, will increase to a lesser extent, than the pressure in chamber A, due to the throttling of fluid between the piston head and the seal 21. The relationship between the pressure in chambers B and A is determined by the ratio of the difference in the areas of the head and piston rod to the area of the head. With an increase in the load of the car, the elastic lever 10 (see fig. 8.3) is loaded more and the force from the lever 5 on the piston increases, i.e. moment of contact between the piston head and the seal 21 (see fig. 8.4) achieved with a higher pressure in the master brake cylinder. Thus, the effectiveness of the rear brakes increases with increasing load.
In case of failure of the brake circuit, the right front-left rear sealing rings 10, the sleeve 19 under the pressure of the liquid in the chamber B will move towards the plug 16 until the plate 11 stops in the seat 14. The pressure in the rear brake will be regulated by the part of the regulator, which includes the piston 2 with seal 21 and bushing 7. The operation of this part of the regulator in the event of a failure of the named circuit is similar to operation in a working system. The nature of the change in pressure at the outlet of the regulator is the same as with a working system. In the event of a brake circuit failure, the left front-right rear brake fluid pressure pusher 20 with bushing 19, sealing rings 10 is shifted towards the piston, pushing it out of the housing. The gap M increases and the gap H decreases. When the valve 18 touches the seat 14, the pressure increase in the chamber C stops, i.e. the regulator in this case works as a pressure limiter. However, the pressure reached is sufficient for reliable operation of the rear brake.
A hole E is made in the body 1, closed by a plug 24. The leakage of liquid from under the plug when it is squeezed out indicates the leakage of the rings 10.