Commercial Driver License (CDL) Class B Practice Test

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Study for the Commercial Driver License (CDL) Class B Test. Study using multiple-choice questions, hints, and explanations. Prepare for your exam effectively!

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Why must air tanks be drained?

To prevent brake failure caused by dust accumulation
To remove water and compressor oil that can freeze in cold weather
To maintain optimal engine performance
To ensure air quality for passengers

The correct answer is: To remove water and compressor oil that can freeze in cold weather

Air tanks must be drained primarily to remove water and compressor oil that accumulate during the air compression process. When air is compressed, moisture tends to condense, leading to the build-up of water in the air tanks. If this water is not drained, it can cause serious issues such as freezing in colder temperatures, which may block air flow and impair the proper functioning of the braking system. This can lead to brake failure or inconsistent braking performance. Additionally, the presence of oil in the air tanks can contaminate the air brake system, which can further contribute to performance issues. Regularly draining the air tanks ensures that the air braking system remains free of moisture and contaminants, thereby promoting safe and reliable operation of the vehicle's braking system. Proper maintenance practices, such as this, are crucial for the safety and effectiveness of commercial vehicles.