感载比例阀（SABS ），从本质上讲，SABS只是一套液压机械装置；感载阀的作用在于保证行驶过程中前后轮负荷的合适比例并确保在汽车紧急制动时后轮不抱死。感载比例阀利用车身与车桥之间的距离变化(外界作用力)来改变弹簧的预紧力，随着车辆载荷的增加，相应地进行调整，使得在任何载荷条件下都能得到一个近似理想的制动力分配 。它安装在制动总泵与后轮制动分泵之间的管道上，由壳体、柱塞、阀门、弹簧等组成。壳体进油孔与制动总泵出油孔相通，出油孔与车轮制动分泵相通。当外界作用力小时，感载比例阀的柱塞在弹簧预紧力的作用下被推至最右边，两孔相通，总泵与分泵压力相等。当外界作用力大于弹簧 预紧力，迫使柱塞左移，令柱塞与阀门接触并关闭了阀门，切断总泵通向分泵的通道；若外界作用力压力继续增大，又会使柱塞右移，柱塞与阀门脱离接触，阀门又被打开，总泵与分泵又相通。这样比例阀反复动作使分泵的液压不断得到调整，也即不断调整了后轮制动力。
load sensing proportional valve (SABS), essentially, SABS is a set of hydraulic mechanical device; load sensing valve role is to ensure that the process of moving front and rear wheel load and ensure the proper proportion in the car when the rear emergency brake without locking. The load sensing valve by the change in distance between the body and the axle (external force) to change the spring preload, as the vehicle load increases, adjusted accordingly, which can get an approximate ideal braking force distribution in any load condition. The utility model is composed of a casing, a plunger, a valve, a spring, etc. the utility model is arranged on a pipeline between the brake master pump and the rear wheel brake branch pump. The oil inlet hole of the casing is communicated with the oil outlet hole of the brake master pump. When the outside force, the feeling of the proportion of the plunger valve under the action of the spring preload is pushed to the right side, the two holes are interlinked, the total pump and pump pressure equal. When the external force is greater than the spring preload, forcing the plunger moves to the left, to make contacts with the valve plunger and closed the valve, cut off the pump to pump the channel; if the pressure continues to increase the external force, and can make the right plunger, plunger out of contact with the valve, the valve has been opened, the total pump and pump connected. This proportion of the repeated action of the valve so that the hydraulic pump constantly adjusted, that is, constantly adjust the rear wheel power.