Air Gauges, Warning Devices and Driver Actions — Applied Knowledge

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Build confidence with 10 original questions about Air Gauges, Warning Devices and Driver Actions — Applied Knowledge. 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

During a routine check, you notice the low air pressure warning light and buzzer activate while driving. What should your immediate action be?

Stop right away and safely park the vehicle

Continue driving until you reach your destination

Increase engine speed to build pressure faster

Apply the parking brake immediately while moving

2 / 10

While driving, you notice the application pressure gauge shows you are using more pressure than usual to maintain speed on a downgrade. What could this indicate?

The parking brake is partially engaged

The brakes may be fading or out of adjustment

The compressor is overheating

The air tanks are overfilled

3 / 10

You are preparing to move a bus with a dual parking control valve after losing main air pressure. What must you consider when using the separate air tank to release the spring brakes?

There is only enough air to release the brakes a few times, so plan moves carefully

The brakes will remain released until the main system is fixed

You can drive as far as you want using the separate tank

The spring brakes cannot be released with the separate tank

4 / 10

While driving, you see the safety valve on your air tank is releasing air. What should you do?

Increase engine speed to build air pressure

Ignore it if the brakes feel normal

Have the fault fixed by a mechanic before driving further

Drain the air tanks immediately

5 / 10

You are inspecting the air brake system and see that the air compressor governor does not stop the compressor at 140 psi. What should you suspect?

The governor may be malfunctioning and needs repair

The brake pedal is stuck

The safety valve is set too low

The air tanks are too small for the system

6 / 10

During cold weather, your vehicle’s air brake system has an alcohol evaporator. What daily maintenance should you perform?

Check and refill the alcohol container as needed

Add water to the air tanks

Disable the evaporator to prevent freezing

Drain the alcohol from the system

7 / 10

You are performing a pre-trip inspection on a truck with a dual air brake system. What should you confirm about the air pressure before driving?

The secondary system has at least 120 psi, regardless of the primary system

The air pressure in both systems is above 40 psi

Both the primary and secondary systems have at least 100 psi air pressure

Only the primary system has at least 80 psi air pressure

8 / 10

During a walkaround inspection, you pull on a slack adjuster and it moves more than one inch where the push rod attaches. What should you do?

Adjust it or have it adjusted before driving

Tighten the air compressor belt

Ignore it if the brakes seem to work

Only check it again at the next scheduled maintenance

9 / 10

You are performing a pre-trip inspection and want to verify the air compressor governor has reached cut-out pressure. What should you observe on the air pressure gauge(s)?

The air pressure stops rising at the manufacturer's specified maximum (typically 120-140 psi)

The application pressure gauge reads zero

The air pressure drops to 55 psi

The low air pressure warning light comes on

10 / 10

You are driving and the air pressure in one system of your dual air brake vehicle drops below 55 psi. What will happen?

Nothing will happen unless both systems lose pressure

The spring brakes will automatically apply right away

The air compressor will shut off

The low air pressure warning will activate and you should stop immediately

Your score is

The average score is 0%

About the Air Gauges, Warning Devices and Driver Actions — Applied Knowledge practice quiz

This practice quiz focuses on Air Gauges, Warning Devices and Driver Actions — Applied Knowledge, 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.

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