Reservoirs and Drains - ONLINE CDL SCHOOL

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Reservoirs and Drains

Build confidence with 10 original questions about Reservoirs and Drains. Review your answers and explanations after finishing.

Supplemental study practice. This is not a government licensing exam or ELDT certification, and does not replace hands-on training. Follow your state’s current handbook.

1 / 10

What can happen if water is not drained from the air tanks and the temperature drops below freezing?

The air tanks will overfill

The water can freeze and cause brake failure

The air compressor will stop working

The brake pedal will become stuck

2 / 10

What is the main reason for draining air tanks regularly on vehicles with air brakes?

To clean the compressor filter

To check the tank for rust

To remove moisture and oil that could cause brake failure

To increase the air pressure in the tanks

3 / 10

If your vehicle does not have automatic air tank drains, when should you drain the air tanks?

Only when the warning light comes on

Before every trip

At the end of each working day

Once a week

4 / 10

What is a feature of automatic air tank drains that helps prevent freezing in cold weather?

Extra large air tanks

Electric heating devices

Oil injection systems

Manual override switches

5 / 10

Why is it important to drain the air tanks on a vehicle with air brakes at the end of each day if the system does not have automatic drains?

To prevent the air compressor from overheating

To remove water and oil that can cause brake failure

To increase the air pressure in the tanks

To lubricate the brake chambers

6 / 10

What should you do if your air brake system has an alcohol evaporator during cold weather?

Drain the air tanks only once a week

Turn off the air compressor

Add water to the air tanks

Check and refill the alcohol container daily

7 / 10

How are most manual air tank drain valves operated?

By pressing a button on the dashboard

By stepping on the brake pedal

By opening the fuel tank cap

By turning a quarter turn or pulling a cable

8 / 10

If your vehicle is equipped with automatic air tank drains, what should you still check for?

That the compressor is running continuously

That the air tanks are always full

That the drains are working properly and tanks are free of moisture

That the air tanks are painted

9 / 10

What is the purpose of the air storage tanks in an air brake system?

To hold compressed air for repeated brake use

To store fuel for the engine

To collect exhaust gases

To cool the brake drums

10 / 10

What can happen if you do not drain the air tanks and moisture builds up?

Brakes could fail due to water freezing or oil contamination

The air tanks will rust immediately

The parking brake will not release

The air compressor will overheat

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The average score is 0%

About the Reservoirs and Drains practice quiz

This practice quiz focuses on Reservoirs and Drains, listed under CDL Practice — Air Brakes. Use it to check what you understand, spot topics to revisit, and connect the material to safe, informed decisions on the road.

Before you begin

Keep your current CDL manual or course notes nearby. Read each prompt carefully and think through why an answer fits, especially when a question describes a vehicle, road, or workplace situation. Licensing rules and procedures can vary, so confirm requirements with current official materials for your state.

After you finish

Review any explanations shown with your results. Note unfamiliar terms or missed concepts, then revisit your manual or course notes before trying again. Use your score to guide study; understanding why an answer is correct matters more than the number alone.

Study note: These quizzes are independent study practice. They are not state licensing exams, official government materials, or ELDT certification, and they do not replace required training.

Explore CDL Tests to find more practice by subject.