Automatic bus brake force adjustment device—a torsion bar load-sensing proportional valve. The load-sensing proportional valve is essentially a hydraulic cylinder fixed on the frame. The position of the plunger of the load-sensing proportional valve is controlled by a torsion bar. One end of the torsion bar acts on the plunger, and the other end is connected to the rear axle by adjusting the tie rod.
When auto is unloaded, the deformation of the rear leaf spring is small, the vertical distance between the rear axle housing and the frame is large, and the torsion bar does not exert any effect on the load-sensing proportional valve. The brake fluid from the brake master cylinder first reaches the C chamber of the load-sensing proportional valve, and then passes through the channel H between the sealing ring 7 and the plunger 1 to reach the D chamber, and flows out from the D chamber to act on the rear brake wheel cylinder. As the pump pressure increases, the hydraulic pressure in chamber D also increases. Since the diameter of the top of the plunger is too large for the diameter of the rod, the pressure at the top of the plunger is greater than the pressure at the rod, and the plunger moves toward one side of the torsion bar 9. When the end of the plunger is in contact with the sealing ring, the passage H is closed, and the two chambers C and D are cut off. C chamber is at the same pressure as the brake master cylinder, while D chamber remains the same. The pressure in chamber D is determined by the structure of the load-sensing proportional valve.
When the auto is fully loaded, the deformation of the rear leaf spring increases, and the torsion bar 9 is rotated by adjusting the pull rod, and the torsion bar acts on the front of the plunger 1 with a certain force, which is greater than the reverse force acting on the top of the plunger, so The plunger moves to the right, so that the H channel is normally open, and the C cavity and the D cavity are directly connected. In this way, the pressure provided by the brake master cylinder directly reaches the rear brake cylinder, so that the pressure in the front and rear brake circuits is the same. When the load is medium, as the vehicle load varies
Similarly, the rear suspension will have different deformations. This means that the force exerted by the torsion bar on the front of the plunger will be proportional to the distance between the rear axle and the frame. If the load increases, the spring deflection increases, and the force exerted by the torsion bar on the front of the plunger increases, and the D cavity needs to be larger
The pressure can close the H channel, so that the rear brake produces a larger braking force than that of no load.
In order to ensure that the load-sensing proportional valve can intervene in the brake circuit when necessary, the tie rod needs to be adjusted. It should be noted that when there is pressure in the hydraulic circuit, the tie rod cannot be adjusted; the inspection should be carried out during the slow pressure increase; when checking the load-sensing proportional valve, all other parts of the brake system should be in good technical condition. After the adjustment, check whether the braking condition of the whole vehicle is good.
