CDL Air Brakes TestAir Brake System PartsMedium
A driver is inspecting an older commercial vehicle not equipped with an air dryer. To prevent ice from forming in the air brake system, what component should be present and regularly maintained?
- AAn alcohol evaporator.
- BA manual condensation drain valve.
- CA moisture separator.
- DA desiccant cartridge.
Show answer & explanationAnswer & explanation
Correct answer: A. An alcohol evaporator.
For older air brake systems without an air dryer, an alcohol evaporator is used to inject alcohol vapor into the air system. This alcohol mixes with any water vapor, lowering its freezing point and preventing ice from forming in the lines and valves during cold weather.
Why the other options are wrong
- B. Manual drain valves remove liquid water, but don't prevent residual water vapor from freezing.
- C. Moisture separators are typically part of air dryers or filters, not a standalone preventative for freezing in older systems.
- D. Desiccant cartridges are found in modern air dryers to absorb moisture, not in older systems using evaporators.
Alcohol Evaporator
An alcohol evaporator is a device in older air brake systems that injects alcohol into the air lines to prevent water vapor from freezing during cold weather.
- Used in systems without air dryers.
- Lowers freezing point of water.
- Requires regular refilling with special alcohol.
Memory trick: No dryer? Alcohol's your savior!