Career upgrade: Learn practical AI skills for better jobs and higher pay.
Level up
PracticeVideosBlogFlashcardsEspañol
All Practice Exams

200+ Free Washington CDL Air Brakes Test Practice Questions

Pass your Washington Commercial Driver License (CDL) Air Brakes Knowledge Test exam on the first try — instant access, no signup required.

✓ No registration✓ No credit card✓ No hidden fees✓ Start practicing immediately
200+ Questions
100% Free
1 / 200
Question 1
Score: 0/0

For the Washington CDL Air Brakes knowledge test, what is the shape and color of the parking brake control knob in most modern CMVs?

A
B
C
D
to track
Same family resources

Explore More CDL Air Brakes Knowledge Test

Continue into nearby exams from the same family. Each card keeps practice questions, study guides, flashcards, videos, and articles in one place.

Alabama CDL Air Brakes Knowledge Test

Practice Questions

Arkansas CDL Air Brakes Knowledge Test

Practice Questions

California CDL Air Brakes Knowledge Test

Practice Questions

Colorado CDL Air Brakes Knowledge Test

Practice Questions

Florida CDL Air Brakes Knowledge Test

Practice Questions

Georgia CDL Air Brakes Knowledge Test

Practice Questions
2026 Statistics

Key Facts: Washington CDL Air Brakes Test Exam

25

Washington DOL Air Brakes questions

Washington DOL CDL Knowledge Test

20

Correct answers required to pass

Washington DOL CDL Knowledge Test

$35

Washington CDL knowledge-test fee

Washington DOL Driver Licensing Fees

180 days

Knowledge score and CLP validity period

Washington DOL CDL Knowledge Test and CLP pages

Study Section 5 of the Washington Commercial Driver Guide. Know governor cut-in around 100 psi and cut-out around 125 psi, daily tank draining, low-air warning before 60 psi, spring-brake application around 20-45 psi, 85-to-100 psi buildup within 45 seconds in dual systems, static and applied leak limits, ABS behavior, brake lag, safe downgrade braking, parking controls, foundation brake inspection, alcohol evaporators, and the legacy front-brake limiting valve. Washington lists the Air Brakes test as 25 questions with 20 correct to pass, the CDL knowledge test fee as $35, CLP fee as $40, CLP validity as 180 days, and knowledge scores as valid for 180 days.

Sample Washington CDL Air Brakes Test Practice Questions

Try these sample questions to test your Washington CDL Air Brakes Test exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 200+ question experience with AI tutoring.

1For the Washington CDL Air Brakes knowledge test, what component compresses air for the air brake system?
A.The air dryer
B.The air compressor
C.The brake chamber
D.The slack adjuster
Explanation: The air compressor pumps air into the air storage tanks. It is driven by the engine, either through belts or directly. The air dryer removes moisture from the compressed air, the brake chamber converts air pressure into mechanical force at each wheel, and the slack adjuster transfers that force to the S-cam. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
2For the Washington CDL Air Brakes knowledge test, what is the typical air compressor governor cut-out pressure range?
A.60 to 80 psi
B.100 to 125 psi
C.125 to 140 psi
D.150 to 175 psi
Explanation: The governor cuts out the compressor (stops pumping) at about 125 to 140 psi. It cuts back in (resumes pumping) at about 100 to 125 psi. This pressure range keeps the system safely above the low-pressure warning threshold of 60 psi while preventing over-pressurization. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
3For the Washington CDL Air Brakes knowledge test, at what pressure does the air compressor governor typically cut IN to resume pumping?
A.60 to 80 psi
B.100 to 125 psi
C.125 to 140 psi
D.145 to 150 psi
Explanation: The governor typically cuts in at 100 to 125 psi, signaling the compressor to resume pumping. It cuts out at 125 to 140 psi when system pressure is sufficient. Together these limits maintain a safe operating range well above the 60 psi low-pressure warning. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
4For the Washington CDL Air Brakes knowledge test, what is the purpose of the air dryer in the brake system?
A.To cool the air before storage
B.To remove moisture and oil before air reaches the tanks
C.To increase compressed air pressure
D.To warn the driver of low pressure
Explanation: The air dryer uses a desiccant cartridge to remove water vapor and oil from compressed air before it enters the storage tanks. Removing moisture prevents corrosion, contamination of brake components, and dangerous freezing of air lines in cold weather. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
5For the Washington CDL Air Brakes knowledge test, what is the function of the wet tank (supply or service reservoir)?
A.It cools brake fluid
B.It is the first storage tank where moisture collects before air moves to the other tanks
C.It supplies air only to the trailer
D.It activates the parking brakes
Explanation: The wet tank is the first storage reservoir downstream of the compressor. Most moisture and oil that gets past the air dryer settles there before clean air moves on to the primary and secondary tanks. Drivers must drain the wet tank daily to prevent contamination of the rest of the system. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
6For the Washington CDL Air Brakes knowledge test, at what pressure does the safety valve in the supply tank typically open to release excess air?
A.100 psi
B.125 psi
C.150 psi
D.200 psi
Explanation: The safety valve, installed in the supply (wet) tank, is set to open at about 150 psi. It is a backup that protects the system if the governor fails to cut out the compressor. If the valve releases, the compressor or governor needs immediate repair. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
7For the Washington CDL Air Brakes knowledge test, what is the role of the foot valve (also called the treadle or service brake valve)?
A.It locks the parking brake
B.It supplies air to the brake chambers in proportion to how hard the driver presses the pedal
C.It drains water from the tanks
D.It controls the trailer air supply
Explanation: The foot valve (treadle valve) meters air to the brake chambers in proportion to how far the driver depresses the brake pedal. Pressing harder sends more air, applying more braking force. Releasing the pedal exhausts air from the chambers, allowing the springs and slack adjusters to release the brakes. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
8For the Washington CDL Air Brakes knowledge test, what does the brake chamber do?
A.Stores compressed air for emergencies
B.Converts air pressure into mechanical force through a pushrod
C.Cools brake drums during use
D.Acts as a backup for the parking brake
Explanation: A brake chamber is a sealed housing with a diaphragm or piston. When air pressure enters, the diaphragm pushes a pushrod outward. The pushrod rotates the slack adjuster and S-cam, which forces the brake shoes against the drum to apply braking force. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
9For the Washington CDL Air Brakes knowledge test, what is the role of the slack adjuster on an S-cam brake?
A.It cushions the impact of hard braking
B.It transfers force from the pushrod to the S-cam and can be adjusted to compensate for lining wear
C.It bleeds water from the system
D.It limits maximum air pressure
Explanation: The slack adjuster is a lever that connects the brake chamber pushrod to the S-cam. As the pushrod extends, the slack adjuster rotates the S-cam, which pushes the brake shoes against the drum. It can be adjusted to maintain proper pushrod travel as brake linings wear. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.
10For the Washington CDL Air Brakes knowledge test, what does the S-cam do in an S-cam drum brake?
A.It releases air from the lines
B.It rotates between the brake shoes, forcing them outward against the drum
C.It cools the brake drum
D.It activates the low-pressure warning
Explanation: The S-cam is an S-shaped piece of steel between the two brake shoes. When the slack adjuster rotates it, the wide part of the S forces the shoes outward against the drum, creating friction and slowing the wheel. When air pressure is released, return springs pull the shoes back and rotate the S-cam to its original position. This Washington item is aligned to Section 5 of the Washington Commercial Driver Guide and FMCSA CDL air-brake knowledge standards.

About the Washington CDL Air Brakes Test Exam

The Washington CDL Air Brakes Knowledge Test covers Section 5 of the Washington Commercial Driver Guide for applicants who need to operate trucks, buses, or other commercial motor vehicles equipped with air brakes. The test focuses on air compressor and governor operation, air storage tanks and draining, low-air warnings, air pressure buildup and leak tests, spring and parking brakes, dual air systems, ABS, brake lag, emergency braking, slack adjusters, foundation brakes, inspection procedures, alcohol evaporators, and older front brake limiting valves. Washington DOL administers CDL written knowledge exams through driver licensing offices under FMCSA CDL standards.

Assessment

25 multiple-choice Air Brakes questions administered by Washington DOL as part of the CLP/CDL knowledge testing process; Washington lists 20 correct answers as the passing score and indicates a skills test is also needed.

Time Limit

No separate official time limit published by Washington DOL or FMCSA for the Air Brakes knowledge test

Passing Score

80% (20 correct out of 25)

Exam Fee

$35 CDL knowledge test; $40 Commercial Learner's Permit; $175 CDL skills test (Washington State Department of Licensing under FMCSA CDL standards)

Washington CDL Air Brakes Test Exam Content Outline

Core Section 5 domain

Air Brake System Parts

Compressor, governor, tanks, drains, alcohol evaporator, safety valve, brake pedal, foundation brakes, slack adjusters, pressure gauges, low-air warning, spring brakes, parking controls, ABS, and older front brake limiting valves.

Core Section 5 domain

Dual Air Brake Systems

Primary and secondary systems, pressure gauges, minimum 100 psi before driving, redundancy, air supply to trailers where applicable, and safe response when one circuit loses pressure.

Core inspection domain

Inspecting Air Brakes

Governor cut-in and cut-out, air buildup rate, static and applied leak checks, low-air warning, spring-brake pop-out, slack adjusters, drums, linings, hoses, parking-brake test, and service-brake test.

Core operation domain

Using Air Brakes

Brake lag, normal stops, controlled braking, stab braking, ABS stops, brake fade, proper downgrade technique, low-air-pressure emergencies, parking, wheel chocks, hot brakes, wet brakes, and cold-weather moisture control.

How to Pass the Washington CDL Air Brakes Test Exam

What You Need to Know

  • Passing score: 80% (20 correct out of 25)
  • Assessment: 25 multiple-choice Air Brakes questions administered by Washington DOL as part of the CLP/CDL knowledge testing process; Washington lists 20 correct answers as the passing score and indicates a skills test is also needed.
  • Time limit: No separate official time limit published by Washington DOL or FMCSA for the Air Brakes knowledge test
  • Exam fee: $35 CDL knowledge test; $40 Commercial Learner's Permit; $175 CDL skills test

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

Washington CDL Air Brakes Test Study Tips from Top Performers

1Memorize the Washington guide pressure numbers before taking mixed practice sets: governor cut-in around 100 psi, cut-out around 125 psi, low-air warning before 60 psi, spring brakes around 20-45 psi, and safety valve at 150 psi.
2Practice the final air-brake check as a sequence instead of isolated facts: governor, leakage, low-air warning, spring-brake pop-out, buildup, parking brake, and service brake.
3Do not skip older-device questions. The Washington guide still covers wig-wags and front brake limiting valves, and they are fair test topics.
4Review ABS as a control aid, not a shorter-stopping-distance guarantee. Washington materials emphasize that ABS helps maintain control during hard braking.
5Tie every inspection answer back to safety: excessive leakage, slow buildup, out-of-adjustment brakes, oil-soaked linings, and damaged hoses must be fixed before driving.

Frequently Asked Questions

Who administers the Washington CDL Air Brakes test?

Washington State Department of Licensing administers CDL written knowledge exams at driver licensing offices that offer testing, under FMCSA CDL standards.

How many questions are on the Washington Air Brakes knowledge test?

Washington DOL lists the Air Brakes knowledge test as 25 total questions.

What score do I need to pass?

Washington DOL lists 20 correct answers out of 25 for the Air Brakes test, which matches the federal 80% CDL knowledge-test pass rule.

What happens if I do not pass the required air-brake tests?

Washington DOL lists an L restriction for drivers who do not pass required air-brake tests. Federal rules also require states to restrict a CLP or CDL when the person is not qualified to operate CMVs equipped with air brakes.

What should I study?

Read Section 5 of the Washington Commercial Driver Guide and drill the inspection numbers: governor pressures, low-air warning, spring-brake pop-out, pressure buildup, leak limits, daily draining, ABS behavior, and brake-lag stopping distance.