CDL General Knowledge TestCombination Vehicles (if applicable)Medium
A driver is inspecting the air tank drain valves on a combination vehicle. What is the primary purpose of draining the air tanks daily?
- ATo remove excess air pressure to prevent over-inflation of tires.
- BTo lubricate the internal components of the air brake system.
- CTo check for leaks in the air tank welds and fittings.
- DTo remove water and oil contaminants that can damage the air brake system.
Show answer & explanationAnswer & explanation
Correct answer: D. To remove water and oil contaminants that can damage the air brake system.
Air brake systems compress air, which can introduce moisture and oil into the system. Draining the air tanks daily removes this accumulated water and oil, preventing corrosion, freezing in cold weather, and damage to brake valves and other components.
Why the other options are wrong
- A. Air tanks are for brake pressure, not tire inflation; a governor controls pressure, not draining.
- B. Draining removes contaminants; lubrication is typically internal to specific components.
- C. While a leak might be noticed, the primary purpose of draining is not to find leaks but to remove contaminants.
Air Tank Draining
Daily draining of air tanks removes accumulated water and oil, protecting the air brake system from damage and ensuring proper function.
- Removes water and oil.
- Prevents corrosion.
- Prevents freezing.
Memory trick: Drain the tank, keep it clean, prevent the brake system from being mean.