Maryland Air Brakes Practice Test
Required if the vehicle you'll drive has air brakes — which in practice means nearly every combination vehicle and most straight trucks. The test covers the parts of an air-brake system (compressor, governor, tanks, valves), the specific pressures where things happen (cut-in, cut-out, low-air warning, spring-brake pop-out), and the inspection sequence for leaks and warning devices. Fail this knowledge test or take the skills test in a vehicle without air brakes, and your license carries an air-brake restriction that keeps you out of most trucking jobs.
Who needs it: Anyone who'll drive a vehicle with air brakes. Skipping it puts an L or Z restriction on the license.
Sample practice questions
The most common type of foundation brake is the:
Answer: S-cam drum brake — S-cam drum brakes are the most common; wedge and disc are less common.
A manually operated drain valve should be opened how often?
Answer: At the end of each driving day — Manual drains must be emptied at the end of each day of driving.
The alcohol evaporator helps:
Answer: Reduce the risk of ice in air brake valves in cold weather — Alcohol reduces ice formation in the valves; you must still drain tanks daily.
Common mistakes on the Air Brakes test
- Mixing up the pressure numbers — cut-out (~125 psi), cut-in (~100 psi), low-air warning (~60 psi) are all tested
- Confusing spring brakes (parking/emergency) with service brakes — which system does what, and when
- Forgetting the air-leak rate limits for the applied and released tests during inspection
- Assuming ABS changes how you brake — the test wants normal braking with ABS, not pumping
Studying with the full Truckcess course does double duty: the theory counts toward the federal ELDT requirement (Truckcess is listed on the FMCSA Training Provider Registry).
Official source: Maryland Motor Vehicle Administration
CDL licensing in Maryland is administered by the Maryland Motor Vehicle Administration. Fees, scheduling, forms, and the official Maryland CDL manual live on the official site: Maryland MVA — official CDL page (verified 2026-08-09).
Truckcess is not affiliated with or endorsed by the Maryland Motor Vehicle Administration. Our practice tests cover the federal CDL knowledge standards (49 CFR Part 383) that every state exam is built on; exact question counts, fees, and procedures vary by state and change over time — the official site is always the authority.
More Maryland practice tests
Full prep courses are one-time from $59 with 12 months of access — mytruckcess.com/cdl.
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