California Air Brakes Knowledge Test CDL Practice Test
Practice with real CA Air Brakes exam questions and detailed explanations. Rated 4.8 stars by 1,000+ drivers.
Written by CDL holders and exam prep experts · Updated April 2026
Free Questions
10
Passing Score
80%
Time Limit
30 minutes
Prerequisites
General Knowledge test must be completed first
What is the Air Brakes Knowledge Test Test?
The Air Brakes knowledge test is required for commercial vehicles equipped with air brake systems. Passing this test demonstrates your knowledge of air brake operation, inspection procedures, and safety protocols, and removes the 'L' restriction from your CDL.
Knowledge test to remove 'L' restriction (no air brakes) from CDL
Topic Breakdown
Air Brake System Components
~8 questions
- Compressor and reservoir systems
- Brake chambers and slack adjusters
- Air lines and fittings
Inspection and Testing
~7 questions
- Pre-trip inspection procedures
- Air pressure tests
- Brake adjustment checks
Safe Driving Practices
~6 questions
- Proper braking techniques
- Following distance requirements
- Downhill braking procedures
Emergency Procedures
~4 questions
- Air pressure loss procedures
- Emergency braking systems
- Brake failure protocols
Free Practice Questions
10 questionsQuestion 1 of 10
A slack adjuster free play needs to be adjusted if it is more than about ____ when you pull hard on it.
Browse California Air Brakes Questions
- 1. A slack adjuster free play needs to be adjusted if it is more than about ____ when you pull hard on it.
- 2. The safety valve is set automatically when pressure is:
- 3. Which procedure is used in controlled braking?
- 4. What is the purpose of the modulating control valve (when equipped)?
- 5. The air compressor governor controls:
- 6. The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks fall below ____ psi.
- 7. Some air brake systems have an alcohol evaporator. What may happen if you don't keep the proper level of alcohol?
- 8. The spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below ____ psi.
- 9. Stab braking:
- 10. To check the free play of manual slack adjusters of S-cam brakes, you should park on:
Study Tips for California
- 1Understand the air brake system components thoroughly
- 2Practice air pressure testing procedures
- 3Memorize safe following distances
- 4Know emergency braking procedures
- 5Review California air brake regulations and inspection requirements
California CDL Information
Age Requirements
Intrastate: 18+ · Interstate: 21+
CDL Renewal
Every 5 years
ELDT Required
Yes — ELDT (Entry-Level Driver Training) from FMCSA-registered provider
California DMV
Official CDL Portal →Career Opportunities
Frequently Asked Questions
If you plan to drive a commercial vehicle equipped with air brakes, you must pass the air brakes knowledge test to remove the 'L' restriction from your CDL.
Air Brakes Study Resources
Be Ready for Your California Air Brakes Test
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