At what air pressure must it be maintained for the spring park brakes to function properly?

Spring park brakes are designed to automatically engage when air pressure in the braking system drops below a specific threshold. For these brakes to function properly, a minimum air pressure of 80 psi must be maintained. This pressure ensures that the air supply is sufficient to release the spring brakes fully, allowing the vehicle to operate safely. If the pressure falls below this level, it may lead to accidental engagement of the park brakes, which can pose safety risks while the vehicle is in operation. Therefore, maintaining air pressure at or above 80 psi is crucial for the reliable and safe performance of spring park brakes.