Which procedure is used for the spring brake test?
Answer: B
With the parking brake and tractor protection valve off, repeatedly press and release the brake pedal until pressure drops to 20 psi.
With the parking brake and tractor protection valve off, repeatedly press and release the brake pedal until pressure drops to 20 psi. The engine may be on or off.
All choices
- AWith a fully charged air system, turn the engine off, release all brakes, let the system settle then monitor pressure drop.
- BWith the parking brake and tractor protection valve off, repeatedly press and release the brake pedal until pressure drops to 20 psi.
- CRelease the parking brake, move forward to 5 mph and apply the brakes firmly. Note any pulling to either side.
Why the other answers are wrong
A. With a fully charged air system, turn the engine off, release all brakes, let the system settle then monitor pressure drop.
Choice A is wrong because the spring brake test requires pressing and releasing the brake pedal to reduce pressure, not just monitoring pressure drop.
C. Release the parking brake, move forward to 5 mph and apply the brakes firmly. Note any pulling to either side.
Choice C is wrong because moving forward and applying brakes to check pulling is a brake performance test, not the spring brake test.
CDL Air Brakes Test Info
Questions on Exam
25
Passing Score
80%
Time Limit
Typically 30 minutes; varies by testing location
The Air Brakes test content is federally standardized, so this question applies in every state. Age limits, fees, and testing procedures do vary — check your state's CDL requirements.
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More CDL Air Brakes Practice Questions
- The spring brakes of a tractor-trailer will activate once air pressure drops to approximately:
- The spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below ____ psi.
- Characteristics of dual air brake systems include:
- Which component of the air brake system cuts-in at 100 psi to allow the air compressor to run?
- The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks fall below ____ psi.