The pressure regulator in the rear brakes

For passenger cars, equipped with a hydraulic brake actuator without ABS, apply a pressure regulator. It is often considered a mysterious host, devoid of the functional. But it is not so - this component is the brake system provides a more stable braking, even on slippery roads at high speed. In this publication we consider the pressure regulator in the rear brakes. Mechanisms of inhibition. During braking, the constituent parts of tire tread slip in the longitudinal direction relative to the coverage. The larger the slip, the more susceptible to the side effects of the wheel, while yuze the slightest impact of cross-wheel shift in the direction. To preserve the stability of the machine under braking especially significant sequence Hughes. If locking the rear wheels occurs before the front, even minor side effects (the helm or gusts of wind drift) can initiate the growing drift car. The car, still coasting, front-wheel clings to the road surface, and rear, locked, slide to the side. As a result, the car starts to rotate around the front formed an "anchor". Anticipatory lock the front wheels due to the formation of an "anchor" the back stabilizes the vehicle. Is highly undesirable when immediately blocked all-wheel drive, although the situation is more favorable than the first version of the wheel lock. With all the possible options for booting the machine, decelerating on all surfaces, the first to be blocked by the front wheels. In practice, the car under braking "bite" nose, unloading the rear wheels, and they begin to "take on the skid" before. To exclude such moments in cars without ABS applies a pressure regulator in the rear brakes. How does a pressure regulator rear brakes. Pressure regulator provides proper balance between the working fluid pressure in the rear and front brakes. Without adjusting their values ??are equal, and for each of the possible options for the vehicle load must be a certain relation, which, to avoid skidding, would provide the advanced blocking the front wheels. Moment when the pressure regulator determines the configuration of its drive, and further balance sheet - its own hydraulics, the drive parameters and unloading under braking the rear suspension. Log regulator connects to the master cylinder and exit - with the rear brakes. Work controller controls the drive, load spring which (torsion or twisted) communicates with the rear axle (suspension arms, transverse bar, beam). Consequently, the fluid pressure in the rear brake mechanisms behind the determined slope down body braking the car and its actual load - the total weight of passengers and luggage. The space housing the pressure regulator is divided into two cavities sealed piston. In this case one of them communicates with the master cylinder, and another - with the rear brakes. At the time of operation, the pressure of fluid in the cavities of the same, but one is affected to a smaller area of ??the piston in the other - on the big one. Consequently, the piston tends to start moving, but it counteracts the internal (centering) the spring. The resistance value of the spring and the ratio of the areas defined by its own characteristics of the regulator. They are chosen so that if the plunger does not have an external pressure (loading), spring drive, he shall be placed in the beginning of closing the valve. As the pressure in the master cylinder is to overcome the efforts of the internal spring, the piston is displaced, causing the valve is blocked, the liquid flow that prevents the growth of pressure in the rear brakes. In the functioning of the regulator in the car on the piston also affects external spring. By lowering the body grows this spring force, a shift piston. This opens the valve, increasing fluid pressure in the rear brakes to the point where he was again closed. Methods for testing the pressure regulator in the rear brakes. In the repair manuals have step by step instruction on the evaluation of the pressure regulator on a stationary car. But the real inhibition to evaluate the work unit believable. This process is a road test, though simplistic. To ensure the safety check and a maximum of correctness of the results must comply with certain conditions. First, you should choose a section of road has the following characteristics: a wide, straight, smooth, with no significant lateral / longitudinal slope, free from the continuous movement of cars and pedestrians; located away from potential hazards such as trees, poles, etc.; coverage should be uniform (eg, dense layer of wet sand), which allows braking easily block the wheels. Secondly, the car should meet the following requirements: Friction brake pads must be bedded in during the previous operation; brakes must be cold, not overheated, tires should have a normal air pressure and uniform wear, does not exceed permissible. Advised to check the car with a driver - with the lowest load. The car should accelerate and then brake, locking all the wheels, removing the motor from the transmission, which squeeze the clutch pedal or turn neutral. Rational first 1-2 times slow to a speed of 25-30 km / h, and then, with no signs of failure (jerks, vibration, leaving cars to the side), proceed to the main stage of testing - braking from a speed of 50-55 km / h . Convenient sequence Hughes monitored by an assistant who can follow the trial from a safe distance (at a distance of 6-10 m). For clarity, we recommend chalk cause radial stripes on the surface of the tire. If the verification holds one person, then he needs to study the long tracks of locked wheels, when comparing the rear which should be shorter. If the prints overlap, reduce the initial rate of deceleration or braking, "softer". Recommendations. In the case where the rear wheels lock before going forward, you want to adjust drive pressure regulator - should gradually reduce the load on the piston. If after the next inspection the rear wheels are not locked at all or much later blocked the front wheels, it should raise a little effort from the drive. A sign of inoperability of the pressure regulator in the rear brakes are outpacing block rear brake, even in cases when the piston is not affected by load. In other words, when the gap between the adjustment screw and piston Max. In the process of leveling rear brakes with the wheels hung recommended to increase the load on the piston shank site, such as inserting a lever between it and the outer spring screwdriver. It is forbidden to dismantle a pressure regulator or replace it, as well as other elements of the drive to other, not recommended by auto manufacturers. If after surgery to replace the front brake pads fell braking and returned to normal after the break-pads (path about 200 km), they should be replaced. After installing the spacers, replacement suspension springs, pressure control, load springs and tires (especially on one axis), should be tested and if necessary, to re-regulation drive.