What is the maximum allowable air pressure loss in the applied leak down test?

The maximum allowable air pressure loss in the applied leak down test is capped at 4 PSI. This standard is crucial in ensuring that the braking system remains effective and efficient. When performing a leak down test, it's essential to assess the ability of the air system to hold pressure, which directly correlates to the health and performance of the brakes.

A loss greater than 4 PSI indicates a potential problem that could compromise the vehicle's braking capabilities, increasing the risk of failure during operation. This benchmark helps ensure that the air system is operating within safe limits, contributing to overall vehicle safety and reliability. By maintaining this standard, drivers can identify any issues promptly and address them before they lead to more serious problems on the road.