What causes air leakage in the handbrake chamber?
2 Answers
Continuous air leakage from the exhaust port of the handbrake valve is caused by poor sealing between the intake valve and its seat. This can be resolved by replacing the intake valve seal using a repair kit. Damage or scoring to the piston seal ring of the spring brake chamber, or scoring on the chamber cylinder wall, can all lead to air leakage in the chamber. When the vehicle is in parking brake mode, air leakage from the relay valve will not cause any malfunction to the vehicle, as this is clearly the intake of the brake valve.
I'm an experienced truck driver and have encountered this issue several times. If the parking brake cylinder is leaking air, it's most likely due to a damaged seal or loose air hose. When compressed air leaks, the parking brake can't hold the vehicle, making it prone to rolling on steep slopes, which is very dangerous. I remember last time on a mountain road, I heard a hissing sound and immediately pulled over to check—it turned out to be dust buildup at the connection point causing the leak. After cleaning it promptly and replacing the seal, it was fixed. During regular maintenance, don’t forget to blow out the air hose connections to prevent dust buildup. If there’s an issue, don’t push your luck—get a mechanic to check it. Also, pay attention to other components in the air system, like insufficient pressure in the air reservoir, which could lead to related failures. It’s better to address small problems before they escalate. Safety comes first—spending time on maintenance is always worth it.
