Maryland Air Brakes Knowledge Test CDL Practice Test
Practice with real MD 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
Typically 30 minutes; varies by testing location
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
Some air brake systems have an alcohol evaporator. What may happen if you don't keep the proper level of alcohol?
Browse Maryland Air Brakes Questions
- 1. Some air brake systems have an alcohol evaporator. What may happen if you don't keep the proper level of alcohol?
- 2. What is the purpose of the modulating control valve (when equipped)?
- 3. Repeatedly partially increasing and pressing the brake pedal may result in:
- 4. The air brake lag distance at 55 mph on dry pavement adds about ____ feet.
- 5. Which procedure is used in controlled braking?
- 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. A slack adjuster free play needs to be adjusted if it is more than about ____ when you pull hard on it.
- 8. The safety valve is set automatically when pressure is:
- 9. The most common type of foundation brake found on heavy vehicles is the:
- 10. The spring brakes of a tractor-trailer will activate once air pressure drops to approximately:
Study Tips for Maryland
- 1Understand the air brake system components thoroughly
- 2Practice air pressure testing procedures
- 3Memorize safe following distances
- 4Know emergency braking procedures
- 5Review state air brake regulations and inspection requirements
Maryland CDL Information
Age Requirements
Intrastate: 18+ · Interstate: 21+
CDL Renewal
Every 8 years
ELDT Required
Yes — ELDT (Entry-Level Driver Training) from FMCSA-registered provider
Maryland MVA
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 Maryland Air Brakes Test
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