If your truck or bus has dual parking control valves, you can use pressure from a separate tank to

If your truck or bus has dual parking control valves, you can use pressure from a separate tank to

• A. release the spring brakes to move the vehicle in an emergency
• B. release the parking brakes to adjust mirrors
• C. power the air compressor
• D. activate the cruise control

Answer: (A)

Spring brakes are held on by springs and normally released by applying air pressure. When a vehicle has dual parking control valves, you can use pressure from a separate reservoir to release those springs even if the main air system isn’t able to supply the release pressure. This lets you move the vehicle in an emergency to reach help or bring it to a safe stop. The other options don’t involve releasing the spring brakes with a separate air source and aren’t relevant to this emergency release capability.

Spring brakes are held on by springs and normally released by applying air pressure. When a vehicle has dual parking control valves, you can use pressure from a separate reservoir to release those springs even if the main air system isn’t able to supply the release pressure. This lets you move the vehicle in an emergency to reach help or bring it to a safe stop. The other options don’t involve releasing the spring brakes with a separate air source and aren’t relevant to this emergency release capability.