What is the reason for air leakage in the parking brake relay valve?
2 Answers
The reason for air leakage in the parking brake relay valve is damage to the intake valve seal of the brake valve or the presence of foreign objects or impurities between the valve and valve seat, resulting in incomplete sealing. Introduction to the relay valve: The relay valve's intake port is connected to the air reservoir, and the outlet port is connected to the brake chamber. When the brake pedal is pressed, the output air pressure from the brake valve serves as the control pressure input for the relay valve. Under the control pressure, the intake valve is pushed open, allowing compressed air to flow directly from the air reservoir through the intake port into the brake chamber, bypassing the brake valve. This significantly shortens the air filling pipeline of the brake chamber and accelerates the air filling process. Therefore, the relay valve is also called an acceleration valve. Function of the relay valve: A differential relay valve is generally used. It prevents simultaneous operation of the driving and parking systems, overlapping forces in the combined spring brake cylinder and spring brake chamber, thereby avoiding overloading of mechanical transmission components and enabling rapid air filling and exhausting of the spring brake cylinder.
I've encountered numerous brake system issues, with the most common cause of air leakage in the hand brake relay valve being aging or damaged seals. Over time, rubber seals can harden and crack, compromising their airtightness and allowing air to escape through the gaps. Another major issue is wear and tear on internal valve components, such as thinning O-rings on the piston, which can lead to loss of air pressure control. Sometimes, careless assembly can damage sealing surfaces, or external impacts can cause cracks, both of which may result in leaks. In harsh road conditions, mud and water corrosion can also accelerate component deterioration. I recommend regularly testing system stability with an air pressure gauge. If there's a leak, don't push your luck—visit a professional shop as soon as possible to replace worn parts and ensure your brakes are safe. This is not something to delay, as air leaks can directly cause brake failure.
