Some air brake systems have an alcohol evaporator. What may happen if you don't keep the unit filled with alcohol?

Some air brake systems have an alcohol evaporator. What may happen if you don't keep the unit filled with alcohol?

• A. ice may form in the tanks and cause the brakes to fail
• B. brakes will last longer
• C. the oil will leak
• D. the tires will wear unevenly

Answer: (A)

The key idea is that the alcohol evaporator is there to prevent moisture in the compressed air from freezing in cold weather. The evaporator adds small amounts of alcohol to the air as it’s dried and stored, which lowers the freezing point of any water that’s present. If you don’t keep the unit filled with alcohol, water in the air system can freeze, forming ice that can clog lines or valves and lead to brakes failing to apply, release, or control properly. That’s why ice forming in the tanks and causing brake failure is the correct consequence. The other options don’t relate to the evaporator’s job, since none involve freezing issues or how the evaporator protects braking performance.

The key idea is that the alcohol evaporator is there to prevent moisture in the compressed air from freezing in cold weather. The evaporator adds small amounts of alcohol to the air as it’s dried and stored, which lowers the freezing point of any water that’s present. If you don’t keep the unit filled with alcohol, water in the air system can freeze, forming ice that can clog lines or valves and lead to brakes failing to apply, release, or control properly. That’s why ice forming in the tanks and causing brake failure is the correct consequence. The other options don’t relate to the evaporator’s job, since none involve freezing issues or how the evaporator protects braking performance.