9.6. Pressure regulator

Fig. 8.4. Pressure regulator: With = 28 — 32 mm (for buses), 13 — 17 mm (for motor vans); 1 — press the lever; 2 — a pin; 3 — the fixing bolt; 4 — an axis of the press lever; 5 — a nut; 6 — an axis; 7 — the case; 8 and 9 — regulator arms; 10 — a lock-nut; 11 — an adjusting bolt; 12 — a load spring; 13 — a spring; 14 — a piston sleeve; 15 — the operating cone; 16 — a clamping spring; 17 — a ball; 18 — a persistent bracket; 19 — a returnable spring; 20 — the plug; 21 — the piston; 22 — a protective cover; 23 — a bridge arm; 24 — a rack; 25 — a spring washer

The regulator of pressure (fig. 8.4) corrects pressure of the brake fluid arriving to brake mechanisms of back wheels depending on loading of the car that prevents a car drift at intensive braking.
The regulator fastens to the left longeron of a frame through an arm 8, and by means of a load spring 12 and are resistant 24 is connected with the back bridge of the car. The load spring the lever 1 affects with the top short end through press the external end of the piston 21, and 24 is connected by the long end through a rack to the arm 23 welded on the back bridge of the car.
The regulator of pressure consists of the case 7 in which the sleeve 14 is installed and the plug 20 is screwed.
The step piston 21 will mix up in the plug and a sleeve, at the same time in the cavity of I which is constantly tied with the main cylinder there is a part of the piston of small diameter, and in the cavity of II which is constantly tied with wheel cylinders of back brake mechanisms — bigger diameter. On the piston the operating cone 15 which influences the ball 17 which is in an opening of a sleeve 14 is fixed. The ball is kept in an opening by a lamellar spring 16.
Load spring 12 which effort in direct ratio to loading of the car, defines the beginning of turning on of the regulator, and a difference of diameters of pistons — adjustment of pressure of the liquid arriving to back brake mechanisms.
To the introduction in operation of the regulator liquid pressure in cavities of I and II is identical as under the influence of a spring 19 and a load spring the 12th piston 21 through a persistent bracket 18 is pressed to a sleeve 14, and the ball 17 is lifted from a saddle by the operating cone 15, as provides free passing of liquid from a cavity of I in a cavity of II.
When braking in the beginning liquid pressure in cavities of I and II will be identical until force received from pressure upon the most part of the piston 21 (a cavity of II) is not more than the sum of forces received from action of springs 12 and 19 and from the liquid pressure upon the area formed between big and small diameters of the piston (a cavity of I). In this case the piston will move to the left (according to the drawing), the operating cone 15 will depart from a ball 17 which will move to a saddle of a sleeve 14, than will separate a cavity of I with a cavity of II. From this point liquid pressure will grow in the cavity of II arriving to back brake mechanisms more slowly and at the same time will be less, than in a cavity of I.
At removal of effort from a brake pedal pressure in a cavity of I falls, the piston 21 will come back to a starting position (in the drawing to the right), and the operating cone, having lifted a ball, will open access of liquid from a cavity of II in a cavity of I.
The sleeve of the 14th piston under the influence of pressure in a cavity of II will move to the left (according to the drawing), and the ball 17 will depart from a saddle under the influence of the operating cone 15, having opened access of liquid from a cavity of II in a cavity of I.
After liquid pressure drop the sleeve of the piston 14 and the piston 21 under the influence of a returnable spring washer 25 and springs 19 will return to a starting position.