Free Vermont DMV CDL — Air Brakes Practice Test 2026
The Vermont CDL — Air Brakes knowledge test has ~25 questions, and you need ~20 correct (80%) to pass. Practice free with questions written from the official Vermont driver handbook — every one has a clear explanation, and you can retake as often as you like with no sign-up.
Content reviewed against official driver handbooks · August 12, 2026
What's on the Vermont written test
The Vermont CDL — Air Brakes knowledge test has ~25 questions; you need ~20 correct (80%) to pass.
Based on the official Vermont exam format — always confirm current details with your state DMV.
Practice by topic
Focus on one area at a time — each topic has its own set of Vermont practice questions.
How to pass the first time
- Read the official Vermont driver handbook at least once before test day.
- Practice by topic to find your weak spots, then fix them.
- Take full-length practice tests until you pass comfortably every time.
- Read every explanation — understanding beats memorizing.
Vermont CDL — Air Brakes test — frequently asked questions
How many questions are on the Vermont CDL — Air Brakes test?
The Vermont CDL — Air Brakes knowledge test has ~25 questions, and you need ~20 correct (80%) to pass. Our practice tests mirror that format.
How many questions can I miss on the Vermont CDL — Air Brakes test?
You can miss up to ~5 of the ~25 questions and still pass — you need ~20 correct, which is 80%.
Can I retake the practice test?
Yes — practice as often as you like, completely free. The questions and answer choices are shuffled each time.
Can I take the Vermont practice test in Spanish?
Yes. Every question here is available in English and Spanish — switch languages anytime. Many states also offer the real knowledge test in languages other than English; confirm what Vermont offers with your DMV.
Can I practice on my phone?
Yes. The practice tests work in any mobile or desktop browser — no app or sign-up needed — so you can study anywhere.
Are these the real DMV test questions?
No. Our questions are original, written from the current official Vermont driver handbook to match the real test's topics and style. We are not affiliated with any DMV or government agency.
What's the best way to study?
Read the Vermont driver handbook, practice by topic to target weak areas, and finish with full-length tests until you consistently pass.
Other Vermont practice tests
Take the CDL — Air Brakes test in another state
Every Vermont question is written from the official Vermont driver handbook and checked against its current edition. DMV Test Free is a free, independent study resource — not affiliated with any DMV or government agency. About DMV Test Free
Vermont CDL — Air Brakes questions with answers
20 sample questions from the Vermont CDL — Air Brakes question bank — each with the correct answer, a short explanation, and the section of the official handbook it comes from.
Show all 20 questions with answers
1. On a drum brake, where is the braking mechanism located?
Correct answer: Inside the drum
The drum sits at the end of the axle with the wheel bolted to it. The shoes and linings that do the braking work from inside the drum, pushing outward against it.
Source: Vermont Commercial Driver's Manual — Section 5.1.8, Foundation Brakes
2. Which statement about spring brakes does NOT match the manual?
Correct answer: Their braking power is unaffected by brake adjustment
The manual says spring brake power relies on properly adjusted brakes; when adjustment is off, the regular brakes and the emergency and parking brakes all suffer. The other three statements match Section 5.1.14.
Source: Vermont Commercial Driver's Manual — Section 5.1.14, Spring Brakes
3. Vermont requires the air brake knowledge test, plus a suitably equipped skills-test vehicle, to be licensed for air-braked commercial vehicles. To which other brake system does the manual apply the same two requirements?
Correct answer: Air over hydraulic brakes
The Skills Test section treats the two alike. To be licensed for a commercial vehicle with air brakes or with air over hydraulic brakes, you pass the air brake knowledge test and bring a vehicle with that kind of brakes to the skills test.
Source: Vermont Commercial Driver's Manual — Skills Test
4. For a vehicle to be controlled safely, each brake has to carry its part of the load. Which brakes does the manual say drop out of that effort first?
Correct answer: The ones that are out of adjustment
Brakes that are out of adjustment quit doing their share before the properly adjusted ones do. That shifts the work to the remaining brakes, which can then overheat and fade.
Source: Vermont Commercial Driver's Manual — Section 5.4.5, Brake Fading or Failure
5. On a long downgrade you are using the manual's brake-and-release technique in the proper low gear. How long do you keep repeating it?
Correct answer: Until you reach the end of the downgrade
The cycle of slowing to about five mph under your safe speed, releasing, and braking again at the safe speed is repeated as many times as needed for the whole grade.
Source: Vermont Commercial Driver's Manual — Section 5.4.6, Proper Braking Technique
6. Which of these is NOT one of the checks in the manual's Step 7 final air brake check?
Correct answer: Pulling on the slack adjusters to check their movement
Slack adjusters are checked earlier, during the Step 5 walk-around. Step 7 covers the governor, leakage rate, the low pressure warning, automatic spring brake application, pressure buildup, the parking brake and the service brakes.
Source: Vermont Commercial Driver's Manual — Section 5.3.3, Step 7 Final Air Brake Check
7. You climb into an older air-braked truck and find a round blue knob on the dash instead of a yellow diamond-shaped one. According to the manual, what might that knob be?
Correct answer: The parking brake control
Section 5.4.8 says newer vehicles use a yellow, diamond-shaped knob labeled for the parking brakes, while older ones may have a round blue knob or another shape, including a lever.
Source: Vermont Commercial Driver's Manual — Section 5.4.8, Parking Brakes
8. On the vehicle inspection test described in Vermont's manual, the air brake check has a set number of components, and missing any one of them means automatic failure. How many components are there?
Correct answer: Three
Section 11 says that not performing all three components correctly means you automatically fail the vehicle inspection test. The three are the applied-brake leakage check, the low air warning check, and the check that the valves pop out as pressure keeps falling.
Source: Vermont Commercial Driver's Manual — Section 11.1.2, Cab Check/Engine Start
9. The manual explains how too much heat produces brake fade. Which of these is NOT part of that explanation?
Correct answer: The air tanks lose pressure as the drums heat up
Fade comes from heat changing the lining chemically, which lowers friction, and from the drums expanding so the shoes have farther to go and make weaker contact. Tank pressure is not part of the manual's account.
Source: Vermont Commercial Driver's Manual — Section 5.4.5, Brake Fading or Failure
10. The manual writes total stopping distance for air-braked vehicles as a sum of four distances in order. Which one comes right after reaction distance?
Correct answer: Brake lag distance
The order is perception distance, reaction distance, brake lag distance, then braking distance. Brake lag is there because air needs a moment to travel through the lines after you press the pedal.
Source: Vermont Commercial Driver's Manual — Section 5.4.4, Stopping Distance
11. On the vehicle inspection test, your truck's air compressor is driven by gears, so there is no compressor belt to check. What does Section 11 have you do?
Correct answer: Tell the examiner it is not belt driven and check that it works properly, is undamaged, is not leaking and is securely mounted
Section 11 lists the air compressor belt among the belts to check for snugness and wear. When a listed component has no belt, you say so to the examiner and confirm the component operates properly, has no damage or leaks, and is securely mounted.
Source: Vermont Commercial Driver's Manual — Section 11.1.1, Engine Compartment (Engine Off)
12. Some vehicles, such as buses, carry a separate air tank tied to the parking brake controls. What is that tank for?
Correct answer: To release the spring brakes so the vehicle can be moved in an emergency
If the main air supply fails, the spring brakes apply. The separate tank holds enough air to release them a few times, which lets the driver get the vehicle out of a dangerous spot.
Source: Vermont Commercial Driver's Manual — Section 5.1.15, Parking Brake Controls
13. A Vermont commercial license carries an air brake restriction, code L, because the skills test was taken in a vehicle without air brakes. What does that restriction mean day to day?
Correct answer: The driver may operate only commercial vehicles that have no air brakes
Vermont's manual spells it out: the L restriction limits you to commercial vehicles without air brakes. It follows from taking the skills test in a vehicle that lacks them.
Source: Vermont Commercial Driver's Manual — Skills Test
14. What is a 'wig wag' on an air-braked vehicle?
Correct answer: A low air warning that drops a mechanical arm into the driver's view
The wig wag is one kind of low air pressure warning. Its arm falls into sight when system pressure goes under 55 psi. An automatic one lifts back out of view once pressure recovers, while a manual-reset one has to be put back by hand.
Source: Vermont Commercial Driver's Manual — Section 5.1.11, Low Air Pressure Warning
15. In the final air brake check you run the engine at a fast idle to test the governor. What on the dash tells you the governor has cut the compressor out?
Correct answer: The pressure reading on your air gauge stops climbing
At about the manufacturer's cut-out pressure the governor stops the compressor, so the gauge reading levels off. After you pump the pressure down with the brake pedal, the compressor should cut back in and the reading should start to climb.
Source: Vermont Commercial Driver's Manual — Section 5.3.3, Step 7 Final Air Brake Check
16. A major leak lets all the air escape from your air brake system. What does the manual say the spring brakes do?
Correct answer: They apply, because the air that held the springs back is gone
Spring brakes are held off by air pressure. Losing all the air through a leak has the same effect as the cab control letting the air out: the springs put the brakes on.
Source: Vermont Commercial Driver's Manual — Section 5.1.14, Spring Brakes
17. To have an air brake restriction removed in Vermont, a driver must get a commercial learner permit and hold it for at least 14 days. What payments does the manual say go with that?
Correct answer: A test fee and a skills deposit
The manual says an applicant who wants a restriction such as air brake taken off must get a commercial learner permit, keep it at least 14 days, and pay a test fee along with a skills deposit.
Source: Vermont Commercial Driver's Manual — Skills Test
18. Your tractor has ABS and your trailer does not. Which two benefits does the manual say you should still get under braking?
Correct answer: Steering control and less chance of a jackknife
With ABS on the tractor alone you should keep steering control and be less likely to jackknife. The trailer can still swing, so the manual has you watch it and ease off the brakes, if that is safe, should it start to come around.
Source: Vermont Commercial Driver's Manual — Section 5.4.2, Braking with Antilock Brakes
19. When you check slack adjusters on s-cam brakes by pulling on them, what does the manual tell you to use?
Correct answer: Gloves
The manual says to put on gloves and pull hard on every slack adjuster within reach. Movement of more than about an inch at the push rod suggests the brake needs adjusting.
Source: Vermont Commercial Driver's Manual — Section 5.3.2, During Step 5 Walk-around Inspection
20. Section 11 has combination-vehicle drivers check the trailer parking brake separately. With air pressure at governor cutout, how is that check set up?
Correct answer: The tractor's parking brake is released and the trailer's is set, then you gently try to pull forward
For the trailer, Section 11 reverses the first parking brake check: the tractor's parking brake is let off, the trailer's is engaged, and you ease forward to confirm the trailer brake alone holds the vehicle.
Source: Vermont Commercial Driver's Manual — Section 11.1.2, Cab Check/Engine Start