During an air brake system test, which checks should you perform?

• A. Listen for hissing sounds, observe for visible leaks, and verify air pressure rises normally.
• B. Check the oil level.
• C. Test the horn volume.
• D. Check seat belt wear.

Answer: (A)

Air brake system safety hinges on leaks and pressure buildup. If there are leaks, or if the system doesn’t build pressure to the normal level, brakes may not function when needed. So you perform checks that focus on sealing and charging the system: listen for hissing sounds that could indicate leaks, look for any visible leaks on hoses and fittings, and verify that the air pressure rises normally to the proper level. These checks together show the system is airtight and able to charge correctly. Other items like oil level, horn volume, or seat belt wear don’t assess the brake system’s pressure or leaks, so they aren’t part of this air brake test.