Why does the parking brake leak air when pulled?

1 Answers
McOwen
07/30/25 4:48am
Issue with the relay valve. Connection to the air reservoir: The relay valve's intake port is connected to the air reservoir, and the air outlet 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 this control pressure, the intake valve is pushed open, allowing compressed air to flow directly from the intake port into the air reservoir. The moving chamber does not pass through the brake valve, which significantly shortens the brake chamber's air filling line and accelerates the chamber's air filling process. Relay valve: The relay valve is part of the vehicle's air brake system. In heavy-duty vehicle brake systems, the relay valve serves to reduce reaction time and pressure build-up time.
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