Massachusetts Air Brakes CDL Practice Test
Below are 25 exam-style questions for the Massachusetts Air Brakes CDL knowledge test, modeled on the FMCSA-aligned content used by the Massachusetts Registry 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 Stay popped out and yellow
- B Stay pushed in
- C Have no indication
- D Flash red
- A The tractor service brakes only
- B The trailer service brakes only
- C The parking brake
- D Both tractor and trailer brakes
- A They are decorative
- B They control trailer height
- C Out-of-adjustment slack adjusters can result in brakes that do not work properly
- D They affect engine performance
- A Federal law mandates them as decorative
- B They reduce stopping distance significantly without normally causing skids on dry pavement
- C They look balanced
- D They make steering easier
- A Steering wander
- B Tire blowouts
- C Engine overheating
- D Wheel lockup during emergency braking
- A Pull forward and apply the foot brake to test for stopping
- B Drain the wet tank
- C Adjust the slack adjusters
- D Check tire pressures
- A Disable the warning lamp
- B Allow the system to reach operating pressure before driving
- C Check the brake light visibility
- D Drain the wet tank
- A Loose drum bolts
- B Visible rust
- C No slack adjuster
- D Pushrod travel within the legal limit for that brake type
- A The service brakes for normal stops
- B The horn
- C The tail lights
- D The headlights
- A Removed for inspection
- B Loose for easy connection
- C Free of dirt and damage and properly seated
- D Coated with oil
- A 20 psi
- B 40 psi
- C Never; only the gauge needs to read it
- D 60 psi
- A 85 psi
- B 40 psi
- C 60 psi
- D 125 psi
- A Light, intermittent braking with engine braking and a low gear
- B Heavy continuous braking
- C Coast in neutral
- D Apply the parking brake
- A It is bad luck
- B It will reduce engine power
- C It can damage the rubber seals
- D It violates federal weight law
- A 0 feet
- B 32 feet
- C 300 feet
- D 142 feet
- A Wait for full system pressure before moving
- B Pump the service brake five times
- C Drain the wet tank
- D Drive immediately
- A 5 psi per minute
- B 4 psi per minute
- C 2 psi per minute
- D 3 psi per minute
- A Listening for a hiss
- B Looking at the gauge
- C Releasing the parking brakes, moving the vehicle slowly forward, and applying the trailer hand valve
- D Pumping them while parked
- A You are about to begin a trip
- B There is no situation in which draining is wrong
- C The vehicle is in motion
- D It is full of moisture
- A Engine RPM
- B When the air compressor will pump air into the storage tanks
- C Brake pad wear
- D Coolant temperature
- A Replace governors
- B Increase pressure
- C Cool the air before it enters the brake chambers
- D Remove moisture and contaminants from the compressed air
- A Show no signs of damage, leaks, or excessive wear
- B Be wrapped in tape
- C Have at least 5 splices each
- D Be coiled tightly under the truck
- A Look at the dashboard light
- B Drain the wet tank only
- C Pump the brake to fan down the pressure and verify the warning activates before pressure drops below 60 psi
- D Disconnect the trailer
- A Press as hard as possible and hold
- B Use stab braking — apply hard, release when wheels lock, re-apply
- C Use only the parking brake
- D Pump rapidly and lightly
- A 20 to 45 psi
- B 90 to 100 psi
- C 60 to 80 psi
- D 0 to 10 psi
Study tips for the Massachusetts Air Brakes exam
The Air Brakes portion of the Massachusetts CDL exam is graded out of the bank of questions the Massachusetts Registry 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 Massachusetts 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 Massachusetts 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 Massachusetts Registry 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 Massachusetts 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 Massachusetts 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 Massachusetts Registry of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: MA General Knowledge · MA Combination Vehicles · MA Hazardous Materials · MA Passenger · MA School Bus · MA Tank Vehicle · MA Doubles / Triples
New to the CDL process in Massachusetts? Read How to apply for a CDL in Massachusetts for the document checklist and step-by-step timeline.