California Air Brakes Practice Test 2026
A vehicle-system knowledge test covering the components, inspection, operation and failure warnings of compressed-air brake systems.
What Is the California Air Brakes Practice Test?
A vehicle-system knowledge test covering the components, inspection, operation and failure warnings of compressed-air brake systems.
This test is for CDL applicants who intend to operate a truck, tractor, trailer or bus equipped with air brakes or air-over-hydraulic brakes. Passing helps avoid an air-brake restriction when the other testing requirements are also completed in a properly equipped vehicle.
Who is this test for?
This test is for CDL applicants who intend to operate a truck, tractor, trailer or bus equipped with air brakes or air-over-hydraulic brakes. Passing helps avoid an air-brake restriction when the other testing requirements are also completed in a properly equipped vehicle.
When is it required?
Required when the applicant will operate an air-brake-equipped CMV. Failure to pass the knowledge test or skills-test in an appropriate vehicle may result in an L or Z restriction.
- Practice questions
- 25
- Passing target
- 80%
- Recommended readiness
- 90%+
- Price
- Free
- Explanations
- Immediate
- Official exam?
- No
Topics Covered on This Test
Air compressor and governor operation
Storage tanks, drains and safety valves
Foundation brakes, S-cams, discs and slack adjusters
Application-pressure and supply-pressure gauges
Low-air warning devices
Spring brakes and parking brakes
Dual air-brake systems
Static and applied leakage tests
Air-pressure buildup and governor cut-in/cut-out
Service-brake testing
Brake lag, fade and safe downgrade braking
ABS operation and warning lamps
Requirements
- ✓ Hold a valid California noncommercial driver license or meet California DMV application requirements.
- ✓ Submit a California driver license/CDL application and required identity, Social Security, residency and lawful-presence documents.
- ✓ Meet applicable vision, medical self-certification and DOT medical-certificate requirements.
- ✓ Pay current California DMV application, testing and endorsement fees.
- ✓ Pass every knowledge test required for the requested CDL class, brake system and endorsements with at least the applicable passing standard.
- ✓ Use the current California Commercial Driver’s Handbook and confirm requirements directly with California DMV.
How to Prepare
- 1Identify every component and explain its function in plain language.
- 2Learn the complete air-brake inspection sequence in the correct order.
- 3Know warning thresholds and what each warning means.
- 4Understand spring-brake behavior during pressure loss.
- 5Practice all 25 questions until inspection and failure scenarios feel automatic.
Take the 25-Question Test
Answer every question. You will receive immediate feedback and a handbook-based explanation before moving forward.
Air Brakes Practice Test
What does the air compressor governor control?
Frequently Asked Questions
Who needs the Air Brakes test?+
Applicants who plan to drive commercial vehicles equipped with air brakes or air-over-hydraulic systems.
What is an L restriction?+
It generally means the driver may not operate a CMV equipped with air brakes.
What is a Z restriction?+
It generally limits the driver from operating a vehicle with a full air-brake system, often after testing in an air-over-hydraulic vehicle.
How many questions are on this practice test?+
Exactly 25 questions, as stated on the category card.
Does passing the written test alone remove a restriction?+
Not necessarily. Vehicle and skills-testing requirements also apply; California DMV determines the steps for a restriction change.
Verify official requirements.
This is a practice resource, not the California DMV examination. Requirements, fees and procedures can change. Confirm current information with California DMV and the official handbook.