During the parking brake "pop" test, the parking brake should pop out at what pressure range?

The parking brake "pop" test is an essential part of the pre-trip inspection process for vehicles, particularly school buses. For a vehicle's parking brake to function correctly, it must engage and release at an appropriate pressure level. The correct range of 20 to 45 psi indicates that the parking brake is designed to operate effectively within this pressure to ensure safety while parked.

In this context, if the pressure is too low, it may not provide sufficient force to keep the vehicle stationary, leading to potential safety hazards. Conversely, if the pressure exceeds the specified range, it might indicate a malfunction or improper calibration in the braking system. Therefore, having the correct pressure range ensures that the parking brake effectively holds the vehicle in place when parked, contributing to overall vehicle safety and compliance with regulations.