New Jersey Air Brakes CDL Practice Test
Below are 25 exam-style questions for the New Jersey Air Brakes CDL knowledge test, modeled on the FMCSA-aligned content used by the New Jersey Motor Vehicle Commission. 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 10 psi
- B 5 psi
- C 1 psi
- D 2-3 psi
- A Perception + reaction + brake-lag + braking distance
- B Reaction distance + braking distance
- C Reaction + braking + brake-lag distance
- D Perception + braking distance
- A Two separate air-brake systems on one set of brake controls
- B Twice the air pressure
- C Two compressors
- D Two governors
- A There is no situation in which draining is wrong
- B The vehicle is in motion
- C You are about to begin a trip
- D It is full of moisture
- A The trailer hand valve releases
- B Nothing happens until you stop
- C Spring brakes apply automatically
- D The engine stops
- A Check tire pressures
- B Drain the wet tank
- C Pull forward and apply the foot brake to test for stopping
- D Adjust the slack adjusters
- A The fuel will leak
- B The engine will not start
- C When pressure drops far enough, spring brakes apply suddenly and the vehicle becomes unmovable
- D It can wake the driver
- A In the middle of the descent
- B Before reaching the top, while still on level ground
- C Once a year
- D At the bottom only
- A A worn seat belt
- B A leak or restriction
- C Normal operation
- D A new compressor
- A Flash red
- B Stay popped out and yellow
- C Have no indication
- D Stay pushed in
- A The headlights
- B The horn
- C The tail lights
- D The service brakes for normal stops
- A 90 to 100 psi
- B 0 to 10 psi
- C 60 to 80 psi
- D 20 to 45 psi
- A Using the trailer hand valve, then engine braking, then a runaway ramp if needed
- B Putting the transmission in reverse
- C Coasting in neutral
- D Honking
- A Worn-out hoses
- B Cold weather
- C Too much air pressure
- D Heat from continuous brake use on long downgrades
- A Engine overheating
- B Tire blowouts
- C Steering wander
- D Wheel lockup during emergency braking
- A Increase engine RPM
- B Continue to the next exit
- C Pump the brakes to keep pressure
- D Bring the vehicle to a safe stop as soon as possible and find the cause
- A Created by the pedal mechanically
- B Released from the storage tanks
- C Built up from zero by the pedal
- D Received from a separate accumulator
- A 125 psi
- B 85 psi
- C 60 psi
- D 40 psi
- A At about 5 mph, applying the brake firmly and feeling for pulling, sticking, or unusual feel
- B Listening to the air gauge
- C Pumping the brakes
- D Driving at 30 mph and slamming on the brakes
- A They drain themselves automatically in all trucks
- B They must be drained completely once a year
- C They must be drained daily to remove water and oil
- D They never need to be drained
- A 5 psi per minute
- B 2 psi per minute
- C 1 psi per minute
- D 3 psi per minute
- A Looking at the gauge
- B Releasing the parking brakes, moving the vehicle slowly forward, and applying the trailer hand valve
- C Listening for a hiss
- D Pumping them while parked
- A Coated with oil
- B Removed for inspection
- C Loose for easy connection
- D Free of dirt and damage and properly seated
- A 5 psi per minute
- B 2 psi per minute
- C 4 psi per minute
- D 3 psi per minute
- A Replace foundation brakes
- B Help prevent wheel lockup but do not necessarily shorten stopping distance
- C Are optional and rarely installed
- D Are required only on hazmat trailers
Study tips for the New Jersey Air Brakes exam
The Air Brakes portion of the New Jersey CDL exam is graded out of the bank of questions the New Jersey Motor Vehicle Commission draws from each year. While the exact bank is not published, every question is sourced from the Air Brakes chapter of the New Jersey 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 New Jersey 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 New Jersey Motor Vehicle Commission 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 New Jersey 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 New Jersey 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 New Jersey Motor Vehicle Commission office.
Already comfortable with this endorsement? Drill another: NJ General Knowledge · NJ Combination Vehicles · NJ Hazardous Materials · NJ Passenger · NJ School Bus · NJ Tank Vehicle · NJ Doubles / Triples
New to the CDL process in New Jersey? Read How to apply for a CDL in New Jersey for the document checklist and step-by-step timeline.