Florida Air Brakes CDL Practice Test
Below are 25 exam-style questions for the Florida Air Brakes CDL knowledge test, modeled on the FMCSA-aligned content used by the Florida Department of Highway Safety and 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 It does not matter
- D Less than 30 seconds
- A 20 to 45 psi
- B 60 to 80 psi
- C 90 to 100 psi
- D 0 to 10 psi
- A They must be drained daily to remove water and oil
- B They must be drained completely once a year
- C They never need to be drained
- D They drain themselves automatically in all trucks
- A The driver inflating the tank with a portable pump
- B The vehicle's motion
- C The brake pedal
- D The compressor pumping air back into the storage tanks
- A Check the brake light visibility
- B Drain the wet tank
- C Disable the warning lamp
- D Allow the system to reach operating pressure before driving
- A In gear
- B Started and stopped repeatedly
- C Running at high RPM
- D Off, with brakes released for the first part
- A 20 psi
- B 60 psi
- C 40 psi
- D Never; only the gauge needs to read it
- A Two separate air-brake systems on one set of brake controls
- B Two governors
- C Twice the air pressure
- D Two compressors
- A It only works while the engine is running
- B It will activate the spring brakes
- C Air leaks could cause the brakes to release and let the vehicle roll
- D It is illegal
- A Be free of cracks longer than half the width of the friction area
- B Be glowing red after stops
- C Have small cracks
- D Be coated with oil
- A Driving too fast for conditions
- B Neither of the above
- C Locking the wheels by braking too hard
- D Both of the above
- A Drain the wet tank
- B Use the trailer hand valve as a parking brake
- C Test the parking brake
- D Make pre-trip inspections
- A 60 psi
- B 85 psi
- C 40 psi
- D 125 psi
- A Out-of-adjustment slack adjusters can result in brakes that do not work properly
- B They are decorative
- C They control trailer height
- D They affect engine performance
- A The tail lights
- B The headlights
- C The horn
- D The service brakes for normal stops
- A Increase engine RPM
- B Bring the vehicle to a safe stop as soon as possible and find the cause
- C Pump the brakes to keep pressure
- D Continue to the next exit
- A Pump rapidly and lightly
- B Use stab braking — apply hard, release when wheels lock, re-apply
- C Use only the parking brake
- D Press as hard as possible and hold
- 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 A leak or restriction
- B A worn seat belt
- C A new compressor
- D Normal operation
- 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 Have no indication
- B Stay popped out and yellow
- C Stay pushed in
- D Flash red
- A Nothing happens until you stop
- B Spring brakes apply automatically
- C The trailer hand valve releases
- D The engine stops
- A 32 feet
- B 142 feet
- C 300 feet
- D 0 feet
- A Doing nothing — the dashboard light is enough
- B Pressing the service brake while parked
- C Setting the parking brake, releasing the service brake, and gently trying to move the vehicle
- D Driving over a curb
- A Air pressure may drop slightly
- B Air pressure increases
- C Air pressure should remain unchanged
- D The compressor cuts out
Study tips for the Florida Air Brakes exam
The Air Brakes portion of the Florida CDL exam is graded out of the bank of questions the Florida Department of Highway Safety and Motor Vehicles draws from each year. While the exact bank is not published, every question is sourced from the Air Brakes chapter of the Florida 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 Florida 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 Florida Department of Highway Safety and 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 Florida 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 Florida 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 Florida Department of Highway Safety and Motor Vehicles office.
Already comfortable with this endorsement? Drill another: FL General Knowledge · FL Combination Vehicles · FL Hazardous Materials · FL Passenger · FL School Bus · FL Tank Vehicle · FL Doubles / Triples
New to the CDL process in Florida? Read How to apply for a CDL in Florida for the document checklist and step-by-step timeline.