In the context of air pressure tests, what indicates a successful procedure for spring brake release?

A successful spring brake release during an air pressure test is indicated when the pressure drops below 80 psi. This is crucial because most air brake systems are designed to operate effectively within a specific pressure range. When the pressure drops below 80 psi, the spring brakes are automatically engaged to ensure safety. This mechanism is a fail-safe design that prevents the vehicle from moving unless there is sufficient air pressure to release the spring brakes.

Maintaining pressure above 80 psi would not indicate a successful release of the spring brakes; instead, it suggests that the brakes may still be engaged. A constant pressure reading would indicate a lack of change but does not effectively demonstrate the brake release. Exceeding 145 psi is outside the typical operational range for most air brake systems, and while it reflects the system's capacity to build pressure, it does not correlate with the release of the spring brakes in the context of the testing procedure.