CDL Air Brakes TestAir Brake System PartsEasy
A driver is conducting a pre-trip inspection on a commercial vehicle equipped with an alcohol evaporator. They observe that the evaporator reservoir is empty. What is the primary purpose of adding alcohol to the air brake system?
- ATo lubricate internal components of the air brake system, reducing wear.
- BTo clean out contaminants and debris from the air lines and valves.
- CTo increase the pressure capacity of the air storage tanks.
- DTo prevent moisture in the compressed air from freezing during cold weather.
Show answer & explanationAnswer & explanation
Correct answer: D. To prevent moisture in the compressed air from freezing during cold weather.
Alcohol evaporators are used in older air brake systems to inject alcohol vapor into the air lines. This alcohol mixes with any moisture present, lowering its freezing point and preventing ice formation in cold temperatures.
Why the other options are wrong
- A. While some components require lubrication, alcohol is not primarily used for this purpose.
- B. Air dryers remove contaminants; alcohol does not primarily clean the system.
- C. Alcohol does not affect the pressure capacity of the tanks.
Alcohol Evaporator
A device, typically found in older air brake systems, that introduces alcohol vapor into the compressed air to prevent moisture from freezing in the air lines and valves during cold weather.
- Prevents ice formation in air brake components.
- Used in cold climates.
- Requires periodic refilling with special alcohol solution.
Memory trick: Alcohol Evaporates Ice.