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What does the brief blast of air you may hear from beneath the cab or frame at intervals on a dryer-equipped truck usually indicate?
- A.The air dryer purge cycle expelling collected moisture and contaminants from its desiccant or separator section
- B.A brake chamber diaphragm has just ruptured
- C.The tractor protection valve has failed open
- D.A tire is losing air into the frame
Correct answer
A. The air dryer purge cycle expelling collected moisture and contaminants from its desiccant or separator section
Why
The purge is a designed, short discharge that cleans the dryer so it can keep drying the next charge of air. Unlike a continuous leak, it stops on its own and repeats with compressor cycles.
Manual topic: Air Brakes - Air Dryers · From the Air Brakes practice bank (AB-227).