Free Arkansas DMV CDL — Air Brakes Practice Test 2026
The Arkansas CDL — Air Brakes knowledge test has ~25 questions, and you need ~20 correct (80%) to pass. Practice free with questions written from the official Arkansas 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 Arkansas written test
The Arkansas CDL — Air Brakes knowledge test has ~25 questions; you need ~20 correct (80%) to pass.
Based on the official Arkansas 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 Arkansas practice questions.
How to pass the first time
- Read the official Arkansas 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.
Arkansas CDL — Air Brakes test — frequently asked questions
How many questions are on the Arkansas CDL — Air Brakes test?
The Arkansas 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 Arkansas 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 Arkansas 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 Arkansas 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 Arkansas 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 Arkansas driver handbook, practice by topic to target weak areas, and finish with full-length tests until you consistently pass.
Other Arkansas practice tests
Take the CDL — Air Brakes test in another state
Every Arkansas question is written from the official Arkansas 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
Arkansas CDL — Air Brakes questions with answers
20 sample questions from the Arkansas 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. Why is a modulating control valve spring-loaded?
Correct answer: So you can feel the braking action as you move the lever
The spring loading gives you a sense of how hard the spring brakes are working. The farther you move the handle, the harder they apply, which lets you control them if the service brakes fail.
Source: Commercial Driver's License Manual — Section 5.1.15, Parking Brake Controls
2. According to the manual, what decides how much heat a brake drum can absorb before it is damaged?
Correct answer: How hard and for how long the brakes are used
Friction between the linings and the drum slows the vehicle and makes heat. The amount a drum can tolerate without damage comes down to the force and duration of your braking, and too much heat can make the brakes quit working.
Source: Commercial Driver's License Manual — Section 5.1.8, Foundation Brakes
3. Outside of an emergency, when should automatic slack adjusters normally need to be adjusted by hand?
Correct answer: Only during brake maintenance and when the adjusters are being installed
Automatic adjusters should only need manual adjustment when the brakes are being serviced or the adjusters are being installed. Adjusting one by hand on the road is just a temporary fix for an emergency.
Source: Commercial Driver's License Manual — Section 5.3.2, During Step 5 Walk-around Inspection
4. With the controlled braking method, how hard do you press the brakes?
Correct answer: Firmly, but short of the point where the wheels lock
Controlled braking means pressing the brakes with maximum force short of locking the wheels, while keeping steering movements very small. If the wheels lock or you need a bigger steering correction, release and reapply as soon as you can.
Source: Commercial Driver's License Manual — Section 5.4.3, Emergency Stops
5. For the 'no air brake equipped CMV' (L) restriction, which braking systems count as air brakes?
Correct answer: Any system that works fully or partly on the air brake principle
For the skills test and the L restriction, air brakes include any braking system that runs wholly or partly on air. That means air-over-hydraulic brakes are covered too.
Source: Commercial Driver's License Manual — Section 1, Restrictions
6. Which vehicles does the manual say must have emergency brakes and parking brakes held on by mechanical force?
Correct answer: All trucks, truck tractors, and buses
All trucks, truck tractors, and buses must have emergency and parking brakes held on mechanically, because air pressure can leak away over time. Spring brakes usually meet this need.
Source: Commercial Driver's License Manual — Section 5.1.14, Spring Brakes
7. On a long downgrade in the right low gear, how firmly should you apply the brakes each time your speed reaches the safe speed?
Correct answer: Just firmly enough to feel a definite slowdown
The manual's technique is to brake just firmly enough for a clear drop in speed, release once you are about 5 mph under your safe speed, and repeat as needed until the grade ends.
Source: Commercial Driver's License Manual — Section 5.4.6, Proper Braking Technique
8. Water and compressor oil in an air brake system tend to settle in one part of each air tank. Where, and why does that matter?
Correct answer: At the bottom of the tank, where each tank's drain valve is located
Water and oil gather at the bottom of the tank, and every air tank has its drain valve down there so they can be let out. Draining the tanks completely gets rid of them.
Source: Commercial Driver's License Manual — Section 5.1.4, Air Tank Drains
9. Partway through a trip, your air compressor quits. What can you still count on from the air already stored in the tanks?
Correct answer: Enough air to use the brakes several times
The storage tanks are sized so the brakes can still be applied several times after the compressor stops. That reserve is limited, so it covers a few applications, not normal driving.
Source: Commercial Driver's License Manual — Section 5.1.3, Air Storage Tanks
10. On the CDL vehicle inspection test, the air brake check has four parts. Which of these is NOT one of them?
Correct answer: A slack adjuster pull test
The four parts are the air gauge and governor cut-out check, the air leakage rate test, the air warning device test, and the emergency brake test. A slack adjuster pull test is not among them.
Source: Commercial Driver's License Manual — Section 11.1.2, Air Brake or Hydraulic Brake Check
11. Your brakes are wet after a long run through heavy spray. How does the manual suggest drying them?
Correct answer: Drive in a low gear and apply the brakes gently to heat them
Applying the brakes lightly as you drive in a low gear warms them up and dries them out. Very wet brakes in freezing weather are also a reason not to set the parking brakes, since they could freeze.
Source: Commercial Driver's License Manual — Section 5.4.8, Parking Brakes
12. You are in the proper low gear on a long downgrade and using the brakes to trim your speed. About how long should each brake application last?
Correct answer: About three seconds
Each application should bring your speed down roughly 5 mph below your safe speed and last about three seconds. Then release, and repeat once you are back up to the safe speed.
Source: Commercial Driver's License Manual — Section 5.4.6, Proper Braking Technique
13. Before troubleshooting a brake adjustment problem on automatic slack adjusters, what should you check first?
Correct answer: That adjuster maker's own service manual, because different brands work differently
Automatic slack adjusters come from different manufacturers and do not all operate alike, so the manual says to consult that specific manufacturer's service manual first.
Source: Commercial Driver's License Manual — Section 5.3.2, During Step 5 Walk-around Inspection
14. You keep driving after the low air warning comes on, and tank pressure keeps dropping. On a typical tractor or straight truck, around what pressure will the spring brakes come fully on?
Correct answer: Typically between 20 and 30 psi
Tractor and straight truck spring brakes come fully on somewhere in the 20 to 45 psi range, usually 20 to 30 psi. The manual says not to wait for that: stop safely as soon as the warning comes on, while the brakes are still under your control.
Source: Commercial Driver's License Manual — Section 5.1.14, Spring Brakes
15. You take your CDL skills test in a truck that has no air brakes. What restriction will the State put on your CDL?
Correct answer: You may not drive any CMV that has air brakes of any kind
Testing in a vehicle without air brakes earns the L restriction, which bars you from every CMV that uses air brakes in any form. The same restriction applies if you skip or fail the air brake part of the knowledge test.
Source: Commercial Driver's License Manual — Section 1, Restrictions
16. Your truck's brake system is designed so that pressing the pedal while the spring brakes are on will not hurt anything. What does the manual still advise?
Correct answer: Make a habit of not pressing the pedal while the spring brakes are on anyway
Not every system is built to prevent damage from the combined force of the springs and air pressure, and the ones that are may not always work. The safest course is to build the habit of staying off the pedal whenever the spring brakes are set.
Source: Commercial Driver's License Manual — Section 5.1.15, Parking Brake Controls
17. Why does an air-braked truck have a brake lag delay that a car with hydraulic brakes does not?
Correct answer: Air needs a little time to travel through the lines to the brakes, while hydraulic brakes work instantly
Brake lag is the time between pushing the pedal and the brakes working. Hydraulic brakes on cars and light or medium trucks act instantly, but in an air system it takes half a second or more for air to flow through the lines.
Source: Commercial Driver's License Manual — Section 5.4.4, Stopping Distance
18. During the walk-around, which brake lining condition is acceptable?
Correct answer: Firmly attached, free of oil and grease, and not worn thin
Linings (the friction material) must not be loose, soaked with oil or grease, or dangerously thin. Mechanical parts should also be in place, not broken or missing.
Source: Commercial Driver's License Manual — Section 5.3.2, During Step 5 Walk-around Inspection
19. While stab braking, you release the pedal after the wheels lock, then jam it down again before the wheels have started turning. What is the result?
Correct answer: The vehicle will not straighten out
After you let off, locked wheels can take up to one second to start rolling. Reapplying before they turn keeps the vehicle from straightening out, so wait for the wheels to roll before braking fully again.
Source: Commercial Driver's License Manual — Section 5.4.3, Emergency Stops
20. You want to pull a trailer that has air brakes. Besides the Air Brakes section, which section of the manual must you also study?
Correct answer: Section 6, Combination Vehicles
The manual says anyone who will pull a trailer with air brakes needs to read Section 6, Combination Vehicles, in addition to the Air Brakes section.
Source: Commercial Driver's License Manual — Section 5, Air Brakes