CDL Air Brakes TestInspecting Air Brake SystemsHard
A technician is inspecting the air tanks on a commercial vehicle. They notice that the primary (supply) tank is accumulating significantly more moisture and contaminants than the secondary (service) tank. What does this most likely suggest about the air dryer?
- AThe air dryer is working correctly, and this is a normal condition.
- BThe air compressor is over-lubricating, causing oil to bypass the dryer.
- CThe primary tank's drain valve is faulty and not sealing properly.
- DThe air dryer is malfunctioning and not effectively removing moisture.
Show answer & explanationAnswer & explanation
Correct answer: D. The air dryer is malfunctioning and not effectively removing moisture.
The air dryer is typically located before the primary (wet/supply) tank in the air system. If the primary tank is accumulating excessive moisture and contaminants, it indicates that the air dryer is failing to remove these from the compressed air before it enters the system. A properly functioning air dryer should significantly reduce moisture and contaminants in all tanks.
Why the other options are wrong
- A. This is incorrect; a properly functioning air dryer should minimize moisture and contaminants in all tanks, especially the primary one.
- B. While over-lubrication is an issue, the question focuses on 'moisture and contaminants' generally. A malfunctioning dryer is the direct cause of these reaching the tank.
- C. A faulty drain valve would prevent draining, but wouldn't explain why contaminants are accumulating in the first place if the dryer was working.
Air Dryer Effectiveness
A properly functioning air dryer is crucial for preventing moisture and contaminants from entering and accumulating in the vehicle's air tanks, thereby protecting the entire air brake system.
- Located before air tanks.
- Removes moisture and contaminants.
- Failure leads to tank contamination.
Memory trick: Wet primary tank? Dryer's sick, not cleaning air, what a trick!