Vermont Air Brakes CDL Practice Test
Below are 25 exam-style questions for the Vermont Air Brakes CDL knowledge test, modeled on the FMCSA-aligned content used by the Vermont Department of Motor Vehicles. Try to answer each question on your own before reading the answer key directly under it. The questions and answer choices are shuffled deterministically per state and endorsement, so the order will stay the same on repeat visits — that lets you genuinely measure your improvement.
- A About 3 minutes in dual systems
- B 10 minutes
- C Less than 30 seconds
- D It does not matter
- A The electrical system
- B The transmission
- C The exhaust system
- D The engine, by belts or directly geared
- A They must be drained completely once a year
- B They drain themselves automatically in all trucks
- C They must be drained daily to remove water and oil
- D They never need to be drained
- A Drive shaft
- B Set of brake chambers
- C Air compressor
- D Engine
- A Wheel lockup during emergency braking
- B Steering wander
- C Engine overheating
- D Tire blowouts
- A Both tractor and trailer brakes
- B The parking brake
- C The trailer service brakes only
- D The tractor service brakes only
- A Are optional and rarely installed
- B Are required only on hazmat trailers
- C Help prevent wheel lockup but do not necessarily shorten stopping distance
- D Replace foundation brakes
- A Off, with brakes released for the first part
- B Running at high RPM
- C Started and stopped repeatedly
- D In gear
- A Be glowing red after stops
- B Have small cracks
- C Be free of cracks longer than half the width of the friction area
- D Be coated with oil
- A They look balanced
- B Federal law mandates them as decorative
- C They reduce stopping distance significantly without normally causing skids on dry pavement
- D They make steering easier
- A 85 psi
- B 40 psi
- C 60 psi
- D 125 psi
- A Use the trailer hand valve as a parking brake
- B Make pre-trip inspections
- C Test the parking brake
- D Drain the wet tank
- A Listening for a hiss
- B Releasing the parking brakes, moving the vehicle slowly forward, and applying the trailer hand valve
- C Pumping them while parked
- D Looking at the gauge
- A Heavy continuous braking
- B Light, intermittent braking with engine braking and a low gear
- C Coast in neutral
- D Apply the parking brake
- A Remove moisture and contaminants from the compressed air
- B Increase pressure
- C Replace governors
- D Cool the air before it enters the brake chambers
- A 5 psi
- B 2-3 psi
- C 10 psi
- D 1 psi
- A Nothing happens until you stop
- B The trailer hand valve releases
- C Spring brakes apply automatically
- D The engine stops
- A 32 feet
- B 0 feet
- C 142 feet
- D 300 feet
- A Have no indication
- B Flash red
- C Stay pushed in
- D Stay popped out and yellow
- A The tail lights
- B The horn
- C The headlights
- D The service brakes for normal stops
- A Engine vacuum
- B Electrical current
- C Hydraulic pressure
- D Air pressure
- A Drain the wet tank
- B Pump the service brake five times
- C Wait for full system pressure before moving
- D Drive immediately
- A It violates federal weight law
- B It will reduce engine power
- C It can damage the rubber seals
- D It is bad luck
- A Pressing the service brake while parked
- B Driving over a curb
- C Setting the parking brake, releasing the service brake, and gently trying to move the vehicle
- D Doing nothing — the dashboard light is enough
- A Two separate air-brake systems on one set of brake controls
- B Twice the air pressure
- C Two compressors
- D Two governors
Study tips for the Vermont Air Brakes exam
The Air Brakes portion of the Vermont CDL exam is graded out of the bank of questions the Vermont Department of Motor Vehicles draws from each year. While the exact bank is not published, every question is sourced from the Air Brakes chapter of the Vermont CDL handbook, which itself is derived from the FMCSA Model Commercial Driver's License Manual. That means studying our practice tests, reading the corresponding handbook chapter, and re-reading the parts you got wrong is genuinely the most efficient route to a first-time pass.
Most successful applicants follow a simple cycle: take the practice test cold, write down every question you missed, open the matching chapter of the official Vermont handbook, re-read the section that contains the right answer, then re-take the practice test 24 to 48 hours later. The 24-hour delay matters — sleep is when your brain commits new information to long-term memory, and CDL knowledge questions reward that kind of consolidated learning rather than cramming.
Pay particular attention to questions that include qualifier words like always, never, only, primary, or most. CDL test writers love to flip the right answer with a single qualifier. When two answer choices look almost identical, pay attention to the verb (is it must, should, or may?) and to any numbers (14 days, 100 air miles, 8 hours, 70/8 split). On endorsement tests in particular, watch for trick framing where a true statement about a different endorsement is offered as the "correct" answer to a question that is actually about Air Brakes.
Test-day logistics matter too. Bring photo ID, your Social Security card or birth certificate, your medical examiner's certificate (DOT card), and proof of state residency if you haven't already submitted those documents. The Vermont Department of Motor Vehicles will not let you sit for the knowledge exam without your documentation, and most offices charge an additional fee for re-attempts. Arrive early — the wait at most CDL testing offices runs 30 to 60 minutes — and silence your phone before the exam begins.
Finally, keep your General Knowledge fundamentals sharp even when you're focused on the Air Brakes exam. Many states administer multiple knowledge tests in a single sitting, and questions on weight definitions (GVWR, GCWR, GAWR), stopping distance, and the pre-trip inspection routine show up across endorsements. If you're unsure on the basics, sit a fresh Vermont General Knowledge practice test before scheduling the real exam.
Next steps
Missed more than four questions? Re-read the Air Brakes study guide and the matching chapter in the official Vermont CDL handbook. Then come back and re-take the test. Once you can score 22 of 25 or higher on three runs in a row, you're in good shape to schedule the real exam at your local Vermont Department of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: VT General Knowledge · VT Combination Vehicles · VT Hazardous Materials · VT Passenger · VT School Bus · VT Tank Vehicle · VT Doubles / Triples
New to the CDL process in Vermont? Read How to apply for a CDL in Vermont for the document checklist and step-by-step timeline.