The relay valve, also known as the acceleration valve, is a part of the automobile air brake system. It is located at the end of a long pipeline and makes the compressed air of the air storage cylinder fill the brake air chamber quickly, such as in the brake system of a trailer or semi-trailer. In the brake system of heavy truck, it is used to shorten the time of aeration and exhaust in the process of applying and releasing the brake, and play the role of accelerating and discharging.

Relay valve works:

    when on the brake pedal, the output of the relay valve pressure as the pressure in the relay valve control input, under the effect of control pressure, the inlet valve will open, then the compressed air directly by the air cylinder through the air inlet into the brake chamber, rather than through the relay valve, which greatly shortens the aeration pipe of the brake chamber, accelerate the air chamber aeration process.

    The relay valve generally adopts differential relay valve to prevent running and stopping system from operating at the same time, and the forces in the combined spring brake cylinder and spring brake chamber overlap, so as to avoid the overloading of mechanical transmission components and the rapid charging and exhaust of the spring brake cylinder. But there may be leakage phenomenon, generally speaking, is caused by the intake valve or exhaust valve sealing lax, and this is the seal component damage or impurities foreign matter produced, disassembly cleaning or replacement of seal components can be solved.