Free Rhode Island DMV CDL — Air Brakes Practice Test 2026
The Rhode Island CDL — Air Brakes knowledge test has ~25 questions, and you need ~20 correct (80%) to pass. Practice free with questions written from the official Rhode Island 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 Rhode Island written test
The Rhode Island CDL — Air Brakes knowledge test has ~25 questions; you need ~20 correct (80%) to pass.
Based on the official Rhode Island 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 Rhode Island practice questions.
How to pass the first time
- Read the official Rhode Island 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.
Rhode Island CDL — Air Brakes test — frequently asked questions
How many questions are on the Rhode Island CDL — Air Brakes test?
The Rhode Island 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 Rhode Island 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 Rhode Island 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 Rhode Island 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 Rhode Island 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 Rhode Island driver handbook, practice by topic to target weak areas, and finish with full-length tests until you consistently pass.
Other Rhode Island practice tests
Take the CDL — Air Brakes test in another state
Every Rhode Island question is written from the official Rhode Island 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
Rhode Island CDL — Air Brakes questions with answers
20 sample questions from the Rhode Island 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. The air compressor on your truck has an oil supply of its own instead of running on engine oil. What does the manual tell you to do about it?
Correct answer: Check the compressor's oil level before you start driving
A compressor is either lubricated by engine oil or carries its own supply. When it has its own, you are expected to look at that oil level before you head out on the road.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Air Compressor)
2. In the proper low gear on a long downgrade, how hard should each brake application be?
Correct answer: Firmly enough that you clearly feel the truck slow down
The technique is to brake firmly enough to feel a clear slowdown, release at about 5 mph under your safe speed, and repeat when you are back up to the safe speed.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Proper Braking Technique)
3. According to Rhode Island's guidelines, which manual are its CDL knowledge tests, including Air Brakes, based on?
Correct answer: The CDL manual from the 2005 CDL Testing System, July 2014 version
The guidelines say every Rhode Island CDL knowledge test draws on the AAMVA-based CDL manual from the 2005 CDL Testing System, in its July 2014 version.
Source: Rhode Island CDL Manual — Guidelines for CDL Applicants (Knowledge Testing)
4. Only your trailer has ABS. While braking, the tractor starts to jackknife and you are losing steering control. What should you do?
Correct answer: Let up on the brakes, if safe, until you regain control
With ABS only on the trailer, the trailer is less prone to swinging out, but the tractor can still lock up. If you lose steering or the tractor begins to jackknife, ease off the brakes when safe until you have control again.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Braking with Antilock Brakes)
5. Your truck has a modulating control valve on the dash for the spring brakes. How does moving the lever farther affect braking?
Correct answer: The farther you move it, the more strongly the spring brakes apply
A modulating valve lets you put the spring brakes on gradually. It is spring-loaded so you can feel the braking, and pushing it further brings the spring brakes on harder, which gives you control of them if the service brakes fail.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Parking Brake Controls)
6. What is the safety relief valve on the first air tank there to prevent, and at about what pressure is it usually set to open?
Correct answer: Too much pressure in the system; about 150 psi
The safety relief valve guards the tank, and the whole system beyond it, against excess pressure and is usually set at 150 psi. If it ever lets air out, something is wrong and a mechanic should fix it.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Safety Valve)
7. On a long downgrade, two of your brakes are badly out of adjustment while the rest are fine. What does the manual warn can happen?
Correct answer: The adjusted brakes take on extra work, overheat and fade, leaving too little braking to control the vehicle
Every brake has to carry its share. Brakes that are out of adjustment quit doing their part first, so the remaining brakes take on more, overheat and fade, and you may run out of braking power.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Brake Fading or Failure)
8. In Rhode Island, you pass the General Knowledge and Air Brakes tests but fail the Combination test. What happens to your Air Brakes result?
Correct answer: It is banked, so you do not have to take it again
Rhode Island banks passing knowledge test scores, so they do not need to be retaken; you would wait five business days to try the Combination test again. If the CLP later expires, though, all knowledge tests must be taken over.
Source: Rhode Island CDL Manual — Guidelines for CDL Applicants (Knowledge Testing)
9. Partway into a trip, the yellow ABS malfunction lamp on your instrument panel comes on and stays lit. What does the manual say it may mean?
Correct answer: ABS may have stopped working at one or more wheels
A lamp that stays on after the start-up bulb check, or lights once you are moving, signals that ABS may no longer be working at one or more wheels. Your normal brakes still work; drive normally and get the system serviced soon.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Antilock Braking Systems (ABS))
10. You have just come down a long, steep grade and your brakes are very hot. You need to park on level ground. What does the manual advise?
Correct answer: Skip the parking brakes, chock the wheels, and let the brakes cool before setting them
Setting the parking brakes while the brakes are very hot can damage them with heat. Hold the vehicle with wheel chocks on level ground and let the brakes cool before using the parking brakes.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Parking Brakes)
11. Automatic slack adjusters keep themselves in adjustment. When does the manual say that self-adjusting happens?
Correct answer: During full brake applications
Automatic slack adjusters adjust themselves during full brake applications. Even so, the manual says they still have to be checked.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Inspecting Air Brake Systems)
12. One half of your dual air brake system has dropped very low on pressure while the other half is normal. How does that affect stopping?
Correct answer: The front or rear brakes lose full effectiveness, so you need more distance to stop
Each half of a dual system works a different set of brakes, typically one for the rear axle or axles and one for the front. If one half runs very low, those brakes are not fully working, so stopping takes longer. Stop safely and get the system repaired.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Dual Air Brake)
13. A Rhode Island applicant passes the Air Brakes knowledge test but takes the skills test in a truck that does not have a full air brake system. What happens?
Correct answer: An L or Z restriction is still noted for vehicles with full air brakes
Rhode Island notes the L or Z restriction when a driver fails the Air Brakes knowledge test, and also when the skills test is taken in a vehicle lacking a full air brake system. Passing the written test alone does not avoid it.
Source: Rhode Island CDL Manual — Guidelines for CDL Applicants (Restrictions)
14. In the manual Rhode Island tests from, a visible low air warning is required to switch on before tank pressure drops under what level?
Correct answer: 60 psi
This edition of the manual sets the line at 60 psi (or half the governor cut-out pressure on older vehicles). It typically shows as a red light, and a buzzer may sound as well.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Low Air Pressure Warning)
15. Near the end of the air brake check, how do you make sure the parking brake can hold the vehicle?
Correct answer: Stop, apply the parking brake, then ease the truck against it in a low gear
To test the parking brake, bring the vehicle to a stop, apply the parking brake, and gently try moving the truck against it in a low gear to confirm it holds.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Inspecting Air Brake Systems)
16. Air-operated disc brakes share some parts with s-cam brakes. Which parts are they?
Correct answer: A brake chamber and a slack adjuster
In air disc brakes, air pressure works through a brake chamber and slack adjuster just as in s-cam brakes, but a power screw takes the place of the s-cam and clamps the rotor between the caliper's pads.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Foundation Brakes)
17. You move from a pickup with hydraulic brakes to a truck with air brakes. After you press the pedal, about how long does it take the air to reach the brakes?
Correct answer: About a half second or more
Hydraulic brakes on cars and light or medium trucks act instantly. With air brakes, the air needs a half second or more to flow through the lines, a delay called brake lag.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Stopping Distance)
18. You will be pulling a trailer equipped with air brakes. Besides the air brakes section, which part of the manual does it tell you to study?
Correct answer: Section 6, Combination Vehicles
The air brakes section is meant for anyone who will drive an air-braked truck or bus or tow an air-braked trailer. Towing such a trailer also means reading Section 6 on combination vehicles.
Source: Rhode Island CDL Manual — Section 5: Air Brakes
19. During a hard stop on a slick road, the ABS computer senses that a wheel is about to lock. What does it do?
Correct answer: Cuts braking pressure back to a safe level so you keep control
ABS watches for wheels that are about to lock. When it senses that, it lowers the braking pressure to a safe level, which helps you keep control instead of skidding.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Braking with Antilock Brakes)
20. According to the manual, which vehicles must be equipped with both emergency brakes and parking brakes?
Correct answer: All trucks, truck tractors and buses
All trucks, truck tractors and buses need emergency and parking brakes, held on by mechanical force because air can eventually leak away. Spring brakes are the usual way to meet that requirement.
Source: Rhode Island CDL Manual — Section 5: Air Brakes (Spring Brakes)