Which pressure levels for the air supply valve and park control valve should pop out at during a pre-trip air brake inspection?

Which pressure levels for the air supply valve and park control valve should pop out at during a pre-trip air brake inspection?

• A. 50 PSI for the air supply valve and 30 PSI for the park control valve
• B. Any pressure, as long as it is roughly equal for both valves
• C. 35 PSI for the air supply valve and 15 PSI for the park control valve
• D. 70 PSI for the air supply valve and 50 PSI for the park control valve

Answer: (A)

In a pre-trip air brake inspection, these valves are tested for their safety-trigger behavior as system pressure drops. Each valve is designed to pop out at a specific low-pressure point to confirm the system will respond correctly if pressure falls. The correct combination is that the air supply valve should pop out at about 50 psi, and the park control valve should pop out at about 30 psi. This pairing matches standard Alberta practice and ensures you still have enough pressure for normal braking while providing a clear safety signal as pressure declines. Other options use incorrect pressures or imply testing at any pressure, which wouldn’t reliably verify the safety mechanisms.

In a pre-trip air brake inspection, these valves are tested for their safety-trigger behavior as system pressure drops. Each valve is designed to pop out at a specific low-pressure point to confirm the system will respond correctly if pressure falls.

The correct combination is that the air supply valve should pop out at about 50 psi, and the park control valve should pop out at about 30 psi. This pairing matches standard Alberta practice and ensures you still have enough pressure for normal braking while providing a clear safety signal as pressure declines. Other options use incorrect pressures or imply testing at any pressure, which wouldn’t reliably verify the safety mechanisms.