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What is the function of the air dryer purge that is heard as a brief blast of air when the compressor reaches cut-out?
- A.It blows collected moisture and contaminants out of the dryer so the desiccant can keep working
- B.It signals that a tank has ruptured
- C.It applies the parking brakes for a test
- D.It warns pedestrians the truck is about to move
Correct answer
A. It blows collected moisture and contaminants out of the dryer so the desiccant can keep working
Why
The purge is normal dryer operation tied to the governor reaching cut-out. A dryer that never purges, or purges constantly, is telling the driver it needs service.
Manual topic: Air Brakes - Air Compressor and Governor · From the Air Brakes practice bank (AB-049).