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Georgia Air Brakes CDL Practice Test

Below are 25 exam-style questions for the Georgia Air Brakes CDL knowledge test, modeled on the FMCSA-aligned content used by the Georgia Department of Driver Services. 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.

Heads up: this is a study tool, not a graded exam. Cover the answer with your hand or a sheet of paper for an honest practice run, then re-read the explanations for any questions you missed. Aim for 22 out of 25 or better, three times in a row, before scheduling the real exam.
Question 1 of 25
A brake check ahead of a downgrade should be done:
  • A Before reaching the top, while still on level ground
  • B At the bottom only
  • C Once a year
  • D In the middle of the descent
Correct answer: A
A brief brake test on level ground at the top reveals problems while you can still stop safely.
Question 2 of 25
After parking a tractor-trailer:
  • A Set both tractor and trailer parking brakes
  • B Leave both released
  • C Set only the tractor parking brake
  • D Set only the trailer parking brake
Correct answer: A
Federal practice is to set both parking brakes when fully parked. The exception is during coupling/uncoupling, where the trailer brakes are set.
Question 3 of 25
Spring brakes do NOT replace:
  • A The horn
  • B The headlights
  • C The service brakes for normal stops
  • D The tail lights
Correct answer: C
Spring brakes are for parking and emergency only — never for normal service braking.
Question 4 of 25
Brake drums in good condition will:
  • A Have small cracks
  • B Be free of cracks longer than half the width of the friction area
  • C Be glowing red after stops
  • D Be coated with oil
Correct answer: B
Cracks longer than half the friction area or any visible heat checks usually fail inspection.
Question 5 of 25
Air pressure should normally build from 50 to 90 psi within:
  • A Less than 30 seconds
  • B About 3 minutes in dual systems
  • C 10 minutes
  • D It does not matter
Correct answer: B
Dual air systems should build from 50 to 90 psi within about 3 minutes at idle.
Question 6 of 25
The air-brake hand valve (trolley valve) operates:
  • A The trailer service brakes only
  • B Both tractor and trailer brakes
  • C The tractor service brakes only
  • D The parking brake
Correct answer: A
The hand valve applies only the trailer service brakes. It is not a parking brake or a substitute for the foot brake.
Question 7 of 25
On a vehicle with dual air brakes, the warning device must come on before pressure in either system drops below:
  • A 60 psi
  • B 20 psi
  • C Never; only the gauge needs to read it
  • D 40 psi
Correct answer: A
The low-air warning must activate before pressure drops below 60 psi in either circuit.
Question 8 of 25
A correctly adjusted brake will have:
  • A Pushrod travel within the legal limit for that brake type
  • B Visible rust
  • C Loose drum bolts
  • D No slack adjuster
Correct answer: A
Pushrod travel must be within the manufacturer's and federal limits — exact value depends on chamber size.
Question 9 of 25
Slack adjusters should be checked because:
  • A They affect engine performance
  • B They control trailer height
  • C Out-of-adjustment slack adjusters can result in brakes that do not work properly
  • D They are decorative
Correct answer: C
Slack adjusters convert pushrod motion into braking force. Out-of-adjustment slack adjusters reduce braking ability and are a common out-of-service item.
Question 10 of 25
A leaking air system on a parked truck is dangerous because:
  • A The engine will not start
  • B The fuel will leak
  • C When pressure drops far enough, spring brakes apply suddenly and the vehicle becomes unmovable
  • D It can wake the driver
Correct answer: C
A bigger problem is en route: if a slow leak goes unnoticed and pressure drops below the spring-brake set point, the brakes apply on the road.
Question 11 of 25
A common practice during a long brake-recharge wait is to:
  • A Check the brake light visibility
  • B Disable the warning lamp
  • C Drain the wet tank
  • D Allow the system to reach operating pressure before driving
Correct answer: D
Always wait for full operating pressure (typically around 120 psi) before moving the vehicle.
Question 12 of 25
When doing the air-leak rate test, the engine should be:
  • A Off, with brakes released for the first part
  • B In gear
  • C Started and stopped repeatedly
  • D Running at high RPM
Correct answer: A
Engine off, brakes released to test static leak rate; then brakes applied and held for the second part.
Question 13 of 25
When the air pressure in the brake system drops too low:
  • A Spring brakes apply automatically
  • B Nothing happens until you stop
  • C The engine stops
  • D The trailer hand valve releases
Correct answer: A
When system pressure drops, typically below 20-45 psi, mechanical springs apply the brakes regardless of driver input.
Question 14 of 25
Modulating valves on the rear axle help prevent:
  • A Tire blowouts
  • B Steering wander
  • C Wheel lockup during emergency braking
  • D Engine overheating
Correct answer: C
Modulating valves and ABS sensors release pressure briefly to keep wheels from locking.
Question 15 of 25
After releasing the parking brake on a tractor, you should:
  • A Pump the service brake five times
  • B Drive immediately
  • C Drain the wet tank
  • D Wait for full system pressure before moving
Correct answer: D
Make sure the system reaches at least the cut-out pressure (typically around 120 psi) before driving.
Question 16 of 25
When testing low-air warning, you should:
  • A Pump the brake to fan down the pressure and verify the warning activates before pressure drops below 60 psi
  • B Disconnect the trailer
  • C Look at the dashboard light
  • D Drain the wet tank only
Correct answer: A
Fan the brakes (engine off) until the warning device activates and confirm it is above 60 psi.
Question 17 of 25
If the ABS warning light comes on while driving, you should:
  • A Pump the brakes hard
  • B Continue driving — you still have normal brakes — and have the system checked at the next opportunity
  • C Disconnect the trailer
  • D Immediately stop on the side of the road
Correct answer: B
A failed ABS system reverts to normal braking. Get it repaired but you can complete the trip.
Question 18 of 25
Brake-lag distance for a CMV traveling 55 mph is approximately:
  • A 0 feet
  • B 300 feet
  • C 142 feet
  • D 32 feet
Correct answer: D
About 32 feet at 55 mph for the brake lag alone — added to reaction and braking distances.
Question 19 of 25
After making the initial brake application, the air-pressure drop should not exceed:
  • A 1 psi
  • B 2-3 psi
  • C 5 psi
  • D 10 psi
Correct answer: B
A small initial drop is normal as the system equalizes — but excessive drop indicates a leak.
Question 20 of 25
Spring-brake pop-out occurs at approximately:
  • A 90 to 100 psi
  • B 20 to 45 psi
  • C 60 to 80 psi
  • D 0 to 10 psi
Correct answer: B
Pop-out is typically between 20 and 45 psi, varying by manufacturer.
Question 21 of 25
In a combination vehicle, with the brakes applied and the engine off, the maximum allowable air loss is:
  • A 4 psi per minute
  • B 2 psi per minute
  • C 3 psi per minute
  • D 5 psi per minute
Correct answer: A
Combination vehicle, brakes applied: 4 psi per minute. Single vehicle, brakes applied: 3 psi per minute.
Question 22 of 25
You should NOT drain the wet tank when:
  • 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
Correct answer: B
Daily draining is a routine task; there is no situation where draining is unsafe (other than while driving).
Question 23 of 25
Air pressure builds back up by:
  • A The vehicle's motion
  • B The brake pedal
  • C The compressor pumping air back into the storage tanks
  • D The driver inflating the tank with a portable pump
Correct answer: C
The engine-driven compressor refills the tanks; the brake pedal only controls release of stored air.
Question 24 of 25
A common reason for compressor failure to keep up is:
  • A A clogged air filter or worn compressor
  • B All of the above
  • C A leak in the brake system
  • D A broken governor
Correct answer: B
Any of these causes can prevent the compressor from maintaining cut-out pressure.
Question 25 of 25
Air-brake hoses should:
  • A Be wrapped in tape
  • B Show no signs of damage, leaks, or excessive wear
  • C Be coiled tightly under the truck
  • D Have at least 5 splices each
Correct answer: B
Damaged or chafed hoses are a common air-brake defect and a frequent out-of-service citation.

Study tips for the Georgia Air Brakes exam

The Air Brakes portion of the Georgia CDL exam is graded out of the bank of questions the Georgia Department of Driver Services draws from each year. While the exact bank is not published, every question is sourced from the Air Brakes chapter of the Georgia 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 Georgia 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 Georgia Department of Driver Services 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 Georgia 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 Georgia 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 Georgia Department of Driver Services office.

Already comfortable with this endorsement? Drill another: GA General Knowledge · GA Combination Vehicles · GA Hazardous Materials · GA Passenger · GA School Bus · GA Tank Vehicle · GA Doubles / Triples

New to the CDL process in Georgia? Read How to apply for a CDL in Georgia for the document checklist and step-by-step timeline.