Washington CDL Air Brakes Practice Test

The Washington CDL Air Brakes test is a multiple-choice knowledge test you take for your commercial learner's permit. Washington State Department of Licensing (DOL) says you need 80% to pass (source).

Last updated Oct 7, 2026. FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC.

By Scott Wilder, Editor

Last reviewed against the Washington CDL manual on October 7, 2026

Scott Wilder on X | scottwilderhq.com

FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC. It offers free exam-style practice tests built from the official CDL manual. FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.

Washington CDL permit facts

What	What Washington says	Source
Air Brakes pass mark	80%	Official page
Air Brakes test questions	25	Official page
CLP fee	$40	Official page
CLP validity	180 days. Renew once within 30 days of expiring for 180 more days. Doubles/triples and hazmat tests do not renew with the CLP	Official page
CLP holding period	Wait 14 calendar days after your original or upgraded CLP before the skills test	Official page
Test languages	The CDL knowledge test comes in English, Spanish, Russian and Serbian-Croatian. Language interpreters are not allowed. The study guide is English only.	Official page

20 question Air Brakes practice test

1. What happens if your air brakes are not adjusted properly?
1. A. Only the regular brakes are affected
2. B. Only the parking brakes are affected
3. C. Nothing, spring brakes work without adjustment
4. D. Neither the regular nor the parking brakes will work right
Show answer
Answer: D. Neither the regular nor the parking brakes will work right
The braking power of spring brakes depends on the brakes being in adjustment.
From the official CDL manual, section 5.1.14.
2. For the air leakage test, you release the parking brake. How do you release it?
1. A. Push the valve in
2. B. Pull the valve out
3. C. Press the foot brake only
4. D. Turn off the compressor
Show answer
Answer: A. Push the valve in
The manual says to release the parking brake by pushing the valve in.
From the official CDL manual, section 5.3.3.
3. Engine off, parking brake released, system fully charged. What is the air loss limit per minute for a single vehicle?
1. A. One psi
2. B. Four psi
3. C. Six psi
4. D. Two psi
Show answer
Answer: D. Two psi
For a single vehicle with the engine off and the parking brake released, the loss rate should be less than two psi in one minute.
From the official CDL manual, section 5.3.3.
4. In Step 7 of the inspection, what do you do on an air brake vehicle?
1. A. Skip the brake check
2. B. Do the air brake checks instead of the hydraulic brake check
3. C. Do the hydraulic brake check only
4. D. Do both the air and hydraulic checks
Show answer
Answer: B. Do the air brake checks instead of the hydraulic brake check
The manual says to do these checks instead of the hydraulic brake check.
From the official CDL manual, section 5.3.3.
5. How does a manual reset wig wag get back out of your view?
1. A. It rises out of view by itself
2. B. You must place it out of view by hand
3. C. The buzzer resets it
4. D. It resets when the engine starts
Show answer
Answer: B. You must place it out of view by hand
A manual reset wig wag must be placed in the out of view position by the driver.
From the official CDL manual, section 5.1.11.
6. One brake on your truck is out of adjustment. What can happen to the other brakes?
1. A. They will cool down
2. B. They will work less
3. C. They will lock up for good
4. D. They can overheat and fade
Show answer
Answer: D. They can overheat and fade
The other brakes must do more work, so they can overheat and fade.
From the official CDL manual, section 5.4.5.
7. You are making a normal stop with air brakes. How should you use the brake pedal?
1. A. Push it down and control the pressure for a smooth stop
2. B. Pump it many times quickly
3. C. Push it to the floor and hold it
4. D. Tap it once and coast
Show answer
Answer: A. Push it down and control the pressure for a smooth stop
You push the pedal down and control the pressure. This gives a smooth, safe stop.
From the official CDL manual, section 5.4.1.
8. What can happen if you often adjust an automatic slack adjuster by hand?
1. A. The brake lag will go away
2. B. The adjuster can wear out early
3. C. The drums will cool faster
4. D. The air pressure will build faster
Show answer
Answer: B. The adjuster can wear out early
Routine adjustment will likely cause premature wear of the adjuster.
From the official CDL manual, section 5.3.2.
9. When is controlled braking possible with air brakes?
1. A. Only after the spring brakes apply
2. B. Only on dry roads
3. C. Only while enough air remains in the tanks
4. D. At any air pressure
Show answer
Answer: C. Only while enough air remains in the tanks
Controlled braking works only while enough air is in the tanks.
From the official CDL manual, section 5.4.7.
10. Your air compressor is belt-driven. What do you check on the belt during the engine compartment check?
1. A. Only that it is the same color as the other belts
2. B. Its length compared with a chart in the cab
3. C. Its condition and how tight it is
4. D. Nothing, because the governor protects the compressor
Show answer
Answer: C. Its condition and how tight it is
The manual says to check the condition and tightness of a belt-driven compressor's belt.
From the official CDL manual, section 5.3.1.
11. Which problem is the most common one found in roadside inspections of air brake vehicles?
1. A. Cracked air tanks
2. B. Broken compressor governors
3. C. Brakes that are out of adjustment
4. D. Missing alcohol in the evaporator
Show answer
Answer: C. Brakes that are out of adjustment
The manual says out-of-adjustment brakes are the most common problem found in roadside inspections.
From the official CDL manual, section 5.3.2.
12. You adjust an automatic adjuster by hand so the pushrod stroke is legal. What did you most likely do?
1. A. Hide a mechanical problem without fixing it
2. B. Reset the governor
3. C. Charge the spring brakes
4. D. Fix the problem for good
Show answer
Answer: A. Hide a mechanical problem without fixing it
The manual says the adjustment generally masks a mechanical problem and does not fix it.
From the official CDL manual, section 5.3.2.
13. Using the proper downgrade technique, about how long should each brake application last?
1. A. About one second
2. B. About three seconds
3. C. About ten seconds
4. D. Until you reach the bottom of the grade
Show answer
Answer: B. About three seconds
The manual says each application should last about three seconds.
From the official CDL manual, section 5.4.6.
14. As you fan off pressure on a straight truck, what should the parking brake valve do at the specified pressure?
1. A. Close and pop out, so the spring brakes come on
2. B. Stay pushed in until pressure reaches zero
3. C. Pop out at about 100 psi
4. D. Push in harder to hold the brakes off
Show answer
Answer: A. Close and pop out, so the spring brakes come on
When pressure falls to the manufacturer's specification, the parking brake valve should pop out and apply the spring brakes.
From the official CDL manual, section 5.3.3.
15. You are using the controlled braking method. How should you move the steering wheel?
1. A. Make large, quick turns
2. B. Hold the wheel tightly and never move it
3. C. Turn it back and forth
4. D. Keep the movements very small
Show answer
Answer: D. Keep the movements very small
Keep steering wheel movements very small during controlled braking.
From the official CDL manual, section 5.4.3.
16. With the foot brake fully applied for one minute, a single vehicle has too much air loss if pressure falls more than what?
1. A. Three psi
2. B. One psi
3. C. Two psi
4. D. Four psi
Show answer
Answer: A. Three psi
With the foot brake held for one minute, a single vehicle loses too much air if pressure falls more than three psi.
From the official CDL manual, section 5.3.3.
17. On older vehicles, the low air warning may come on before pressure falls below what?
1. A. The pressure at which the governor cuts in
2. B. A fixed 20 psi on every vehicle
3. C. One half of the governor cutout pressure
4. D. The pressure at which the safety valve opens
Show answer
Answer: C. One half of the governor cutout pressure
For older vehicles the manual gives one half of the compressor governor cutout pressure.
From the official CDL manual, section 5.1.11.
18. Your brakes are wet. How can you dry them before parking?
1. A. Press them hard at high speed
2. B. Use them lightly while driving in a low gear
3. C. Drain the tanks
4. D. Set the parking brake right away
Show answer
Answer: B. Use them lightly while driving in a low gear
The manual says to use the brakes lightly in a low gear to heat and dry them.
From the official CDL manual, section 5.4.8.
19. A dual air brake vehicle has a bad low pressure warning. What does the manual say can happen?
1. A. Nothing, because a dual system never loses air
2. B. The spring brakes will release and the vehicle may roll
3. C. The brakes will work better because of the second circuit
4. D. Stopping distance goes up, with limited braking before the spring brakes come on
Show answer
Answer: D. Stopping distance goes up, with limited braking before the spring brakes come on
In a dual system, a failed warning means longer stopping distance and only limited braking before the spring brakes apply.
From the official CDL manual, section 5.3.3.
20. Which four parts add up to total stopping distance for a vehicle with air brakes?
1. A. Perception, reaction, and braking distance only
2. B. Perception, reaction, brake lag, and braking distance
3. C. Reaction, brake lag, braking distance, and engine braking
4. D. Perception, brake lag, and engine braking distance
Show answer
Answer: B. Perception, reaction, brake lag, and braking distance
Air brakes add brake lag distance to perception, reaction, and braking distance.
From the official CDL manual, section 5.4.4.

Washington CDL Air Brakes questions

What score do you need to pass the Washington CDL Air Brakes test?

Washington says you need 80% to pass the Air Brakes test.

Is the Washington CDL Air Brakes test the same as other states?

The Air Brakes test is built on the same federal knowledge standards in every state, so the topics match the CDL manual. Washington uses its own handbook: https://dol.wa.gov/media/pdf/42/cdlguidepdf

How much does a CDL permit cost in Washington?

CLP fee: $40.

What languages is the Washington CDL knowledge test offered in?

The CDL knowledge test comes in English, Spanish, Russian and Serbian-Croatian. Language interpreters are not allowed. The study guide is English only.

Sources

https://dol.wa.gov/driver-licenses-and-permits/commercial-driver-licenses-cdl/cdl-training-and-testing/cdl-knowledge-test
https://dol.wa.gov/driver-licenses-and-permits/commercial-driver-licenses-cdl/cdl-training-and-testing/commercial-learners-permit-clp
https://dol.wa.gov/driver-licenses-and-permits/commercial-driver-licenses-cdl/cdl-training-and-testing/cdl-skills-test
https://dol.wa.gov/media/pdf/42/cdlguidepdf
Manual sections used in this test: 5.1.11; 5.1.14; 5.3.1; 5.3.2; 5.3.3; 5.4.1; 5.4.3; 5.4.4; 5.4.5; 5.4.6; 5.4.7; 5.4.8

Air Brakes practice test in nearby states