CDL Air Brakes TestInspecting Air Brake SystemsMedium
During a pre-trip inspection, a driver observes excessive moisture and oil residue when draining the air tanks. What does this indicate about the air compressor?
- AThe air dryer desiccant cartridge is saturated.
- BThe air compressor is passing too much oil.
- CThe air compressor governor is set too high.
- DThe air compressor is functioning optimally.
Show answer & explanationAnswer & explanation
Correct answer: B. The air compressor is passing too much oil.
Excessive oil in the air tanks suggests that the air compressor's piston rings or other internal components are worn, allowing engine oil to pass into the air system. This can contaminate and damage air brake components.
Why the other options are wrong
- A. While a saturated air dryer would lead to excessive moisture, it wouldn't explain the presence of oil residue.
- C. A high governor setting would lead to higher pressure, but not directly cause oil contamination.
- D. Optimal function would not result in excessive oil or moisture in the tanks.
Air Compressor Oil Passage
When an air compressor passes excessive oil, it indicates internal wear (e.g., piston rings) allowing engine oil to enter the air system, contaminating components.
- Evident as oil residue in drained air tanks.
- Contaminates air dryer, valves, and brake chambers.
- Requires compressor repair or replacement.
Memory trick: Oil in the tanks, compressor's got leaks!