SABS (SABS), in essence, SABS is just a set of hydraulic mechanical devices; The function of the load sensing valve is to ensure the proper proportion of the front and rear wheel loads during driving, and to ensure that the rear wheel does not lock up when the automobile is braked urgently. Sabs uses the change of the distance (external force) between the car body and the axle to change the pre-tightening force of the spring, and makes corresponding adjustments with the increase of vehicle load, so that an approximate ideal braking force distribution can be obtained under any load condition. It is installed on the pipeline between the master brake cylinder and the rear wheel brake cylinder, and consists of a shell, a plunger, a valve, a spring, etc. The oil inlet hole of the shell is communicated with the oil outlet hole of the master brake cylinder, and the oil outlet hole is communicated with the wheel brake cylinder. When the external force is small, the plunger of sabs is pushed to the extreme right under the pre-tightening force of the spring, the two holes are connected, and the pressure of the master cylinder and the slave cylinder is equal. When the external force is greater than the pre-tightening force of the spring, the plunger is forced to move to the left, so that the plunger contacts the valve and closes the valve, cutting off the passage from the master cylinder to the sub-cylinder; If the external pressure continues to increase, the plunger will move to the right, the plunger will be out of contact with the valve, the valve will be opened again, and the master cylinder and the slave cylinder will be connected again. In this way, the repeated action of the proportional valve makes the hydraulic pressure of the cylinder continuously adjusted, that is, the braking force of the rear wheel continuously adjusted.