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Free Practice Questions for MA CDL Air Brakes

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Key Facts: MA CDL Air Brakes Exam

25

Questions on the Massachusetts Air Brakes knowledge test

Mass.gov CLP page

25 min

Time allowed for the Air Brakes knowledge test

Mass.gov CLP page

20 of 25

Correct answers needed to pass (80%)

Mass.gov CLP page; 49 CFR 383.135

55 psi

Low air warning must come on at or before this pressure

Massachusetts CDL Manual, Section 5 and air brake check

10

Parts of the Massachusetts air brake check on the skills test

Massachusetts CDL Manual, Section 11.1.2

The Massachusetts RMV Air Brakes test has 25 questions, a 25-minute limit, and requires 20 correct. Key figures from the Massachusetts CDL Manual: governor cut-in about 100 psi and cut-out about 125 psi (120–140 psi in the skills-test check), low air warning before 55 psi, spring brakes at 20–45 psi, and per-minute leakage limits (single vs. combination) of under 2 vs. 3 psi with brakes released and under 3 vs. 4 psi with brakes applied.

Sample MA CDL Air Brakes Practice Questions

Try these sample questions to review concepts for the MA CDL Air Brakes exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 220+ question experience with AI tutoring.

1The Massachusetts CDL Manual divides air brakes into three braking systems. Which one uses parts of the service and parking brake systems to stop the vehicle when the brake system fails?
A.The dual-circuit brake system
B.The secondary brake system
C.The emergency brake system
D.The auxiliary retarder system
Explanation: Section 5 says air brakes are really three different braking systems: service, parking, and emergency. The service brakes work when you use the pedal in normal driving, the parking brakes work when you use the parking brake control, and the emergency brake system uses parts of the service and parking systems to stop the vehicle in a brake system failure.
2Your truck's air compressor has its own oil supply instead of using engine oil. What does the Massachusetts CDL Manual tell you to do?
A.Check the compressor's oil level before driving
B.Drain the compressor oil at the end of each day
C.Add alcohol to the compressor oil in cold weather
D.Change the oil whenever the governor cuts out
Explanation: The compressor is driven by the engine through gears or a v-belt and may be lubricated by engine oil or by its own oil supply. If it has its own oil supply, the manual tells you to check the oil level before driving.
3A new driver asks what the air compressor governor is responsible for. Which answer is correct?
A.How much air reaches the brake chambers when you press the pedal
B.The pressure at which the safety valve releases excess air
C.The point at which the spring brakes apply after air is lost
D.When the air compressor pumps air into the storage tanks
Explanation: The governor controls when the compressor pumps air into the air storage tanks. It stops the compressor at the cut-out pressure (around 125 psi) and lets it start pumping again when tank pressure falls to the cut-in pressure (around 100 psi).
4Section 5 of the Massachusetts CDL Manual says the governor stops the compressor when tank pressure rises to the cut-out level. About what pressure is that?
A.About 100 psi
B.About 125 psi
C.About 150 psi
D.About 85 psi
Explanation: Section 5 puts the cut-out level at around 125 psi. The Massachusetts air brake check describes governor cut-out as approximately 120 to 140 psi or the level the manufacturer specifies, so always know your own vehicle's figure.
5With the engine running, you step on and off the brake pedal and watch tank pressure fall from cut-out. At about what pressure should the governor let the compressor start pumping again?
A.About 55 psi
B.About 100 psi
C.About 125 psi
D.About 45 psi
Explanation: The governor cuts the compressor back in at around 100 psi, and the gauge should then start to rise. If it does not, the governor may need repair, because it may not keep enough pressure for safe driving.
6If the air compressor stops working, what does the Massachusetts CDL Manual say the air storage tanks can still do?
A.Keep the brakes released for the rest of the trip
B.Supply the trailer but no longer the tractor
C.Keep the spring brakes applied until air pressure returns
D.Hold enough air to let you use the brakes several times
Explanation: The number and size of air tanks vary, but they hold enough air to allow the brakes to be used several times even if the compressor stops working. That reserve is limited, so a compressor failure still calls for a prompt, safe stop.
7Why does the Massachusetts CDL Manual say air storage tanks must be drained completely?
A.Water and oil collect there, and water can freeze and cause brake failure
B.Draining lowers tank pressure so the governor can cut in more often each trip
C.Draining removes alcohol vapor that would corrode the brake lines
D.Draining resets the low air pressure warning for the next trip
Explanation: Compressed air usually carries some water and compressor oil, which are bad for the air brake system. They collect at the bottom of the tanks, and in cold weather the water can freeze and cause brake failure, so each tank has a drain valve.
8Your truck's air tanks have manually operated drain valves. How are they operated, and when does the manual say you must drain the tanks?
A.With a dash switch, once a week
B.By pressing the brake pedal down hard, before every trip begins
C.By a quarter turn or pulling a cable, after each day of driving
D.By a mechanic only, at each annual state inspection of the vehicle
Explanation: Manual drain valves are opened by turning a quarter turn or by pulling a cable. The manual says you must drain the tanks yourself at the end of each day of driving.
9Which statement about automatic air tank drains matches the Massachusetts CDL Manual?
A.They make manual draining impossible on that tank
B.They work only while the low air warning is on
C.They must be removed in winter because they always freeze up
D.They expel water and oil and may also allow manual draining
Explanation: Automatic drains expel water and oil automatically, and the tanks may be equipped for manual draining as well. Automatic drains are also available with electric heating devices that help keep the drain from freezing in cold weather.
10Some air brake systems have an alcohol evaporator. What is it for?
A.Reducing the risk of ice in valves during cold weather
B.Cooling hot brake drums after long downgrades
C.Cleaning compressor oil out of the air storage tanks
D.Lubricating the slack adjusters during cold winter driving
Explanation: An alcohol evaporator puts alcohol into the air system to reduce the risk of ice in air brake valves and other parts during cold weather. Ice inside the system can make the brakes stop working.

About the MA CDL Air Brakes Exam

The Massachusetts CDL Air Brakes Knowledge Test is the RMV's 25-question test for drivers who will operate commercial vehicles with air brakes. Failing or skipping it leaves an L restriction on the CLP or CDL. Independent practice by OpenExamPrep covers Section 5 of the Massachusetts CDL Manual, the RMV's ten-part air brake check, and the L and Z restriction rules. The practice questions are a study aid; they do not replace performing the air brake check in a real vehicle.

Exam sponsor: Massachusetts Registry of Motor Vehicles (RMV). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

A 25-question multiple-choice Air Brakes knowledge test at an RMV Service Center (offered in English, Spanish, and Portuguese). Drivers who want air brake privileges must also take the CDL skills test in a vehicle with air brakes and correctly explain and perform all ten parts of the Massachusetts air brake check during the Vehicle Inspection test.

Time Limit

25 minutes

Passing Score

80% (at least 20 of 25 questions correct)

Exam / Certification Fees

$10 CDL endorsement test fee with the CLP application or same transaction; $30 if taken on a different day (Mass.gov lists air brakes as the A endorsement)

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

Manual Section 5.1 (official weight not published)

Air Brake System Parts

Compressor and governor (cut-in about 100 psi, cut-out about 125 psi), tanks and drains, alcohol evaporator, 150 psi safety valve, foundation brakes, gauges, the 55 psi low air warning, spring brakes (20–45 psi), parking controls, and ABS.

Manual Section 5.2 (official weight not published)

Dual Air Brake Systems

Primary and secondary systems, building at least 100 psi in both before driving, warning signals in either system, and what happens when one half loses pressure.

Manual Section 5.3 (official weight not published)

Inspecting Air Brakes

Air brake items in the seven-step inspection: compressor belt, slack adjusters (about one inch of free play), automatic adjusters, drums, linings, hoses, and the final air brake check.

Manual Section 5.4 (official weight not published)

Using Air Brakes

Normal and emergency stops, braking with ABS, brake lag (about 32 feet at 55 mph), brake fade, downgrade braking technique, low air pressure, and parking brake precautions.

Manual preface and Section 11.1.2 (official weight not published)

Massachusetts Air Brake Check

The ten-part skills-test air brake check: wheel chocking, governor cut-out, static and applied leakage (90 psi application), low air warning at or before 55 psi, knob pop-out, build-up rate, cut-in, parking brake, and service brake tests.

Manual preface and Section 1; Mass.gov CDL pages (official weight not published)

Massachusetts Licensing Rules

L and Z restrictions, the unprinted A endorsement, restriction removal, road test requirements, and air brake testing for school bus drivers.

Preparing for the MA CDL Air Brakes Exam

What You Need to Know

  • Passing score: 80% (at least 20 of 25 questions correct)
  • Assessment: A 25-question multiple-choice Air Brakes knowledge test at an RMV Service Center (offered in English, Spanish, and Portuguese). Drivers who want air brake privileges must also take the CDL skills test in a vehicle with air brakes and correctly explain and perform all ten parts of the Massachusetts air brake check during the Vehicle Inspection test.
  • Time limit: 25 minutes
  • Exam / certification fees: $10 CDL endorsement test fee with the CLP application or same transaction; $30 if taken on a different day (Mass.gov lists air brakes as the A endorsement) Official sources

Using Our Practice Resources

  • Work through all 220 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

MA CDL Air Brakes: Suggested Study Strategy

1Use the Massachusetts manual's figures: cut-in about 100 psi, cut-out about 125 psi (120–140 psi in the skills-test check), safety valve 150 psi, low air warning before 55 psi, and spring brakes at 20–45 psi.
2Learn the leakage limits as two pairs: brakes released, under 2 psi (single) and 3 psi (combination) per minute; brakes applied at 90 psi or more, under 3 psi and 4 psi.
3Practice saying all ten parts of the Massachusetts air brake check in order, including where the chocks go; missing any part is an automatic failure of the Vehicle Inspection test.
4For downgrades, get into the proper low gear first, brake for a definite slowdown until about 5 mph below your safe speed, release, and repeat.

Frequently Asked Questions

How many questions are on the Massachusetts CDL Air Brakes test?

Mass.gov lists the Air Brakes knowledge test at 25 questions with 25 minutes allowed. You need 20 correct answers (80%) to pass.

What is the L restriction on a Massachusetts CDL?

L means "No air brake equipped CMV." It is added if you fail or do not take the air brake knowledge test, or if you take the skills test in a vehicle without air brakes. It covers any brake system that works fully or partly on air.

What is the Z restriction?

Z means "No full air brake equipped CMV." It is added if you take the skills test in a vehicle with air-over-hydraulic brakes, and it bars vehicles whose brakes work fully on air.

What languages is the Massachusetts CDL Air Brakes test offered in?

Mass.gov says the CLP general knowledge exam and all endorsement exams are available in English, Spanish, and Portuguese. This practice bank is written in English.

What leak rates does the Massachusetts air brake check allow?

With the engine off and the parking brakes released, the loss must be under 2 psi per minute for a single vehicle and under 3 psi for a combination. With the service brake fully applied (90 psi or more), it must be under 3 psi for a single vehicle and under 4 psi for a combination.

How do I remove an air brake restriction in Massachusetts?

The Massachusetts CDL Manual says removing the air brake restriction requires a skills test in addition to the knowledge test, in a vehicle equipped with air brakes. The RMV's endorsements table lists it as the "A Endorsement (L restriction Removal)," which requires a written exam and road test.

Do these practice questions prepare me for the in-vehicle air brake check?

They help you learn the steps, pressures, and limits of the Massachusetts ten-part air brake check, but they are multiple-choice study questions. You still have to explain and perform every part of the check in a real vehicle during the skills test.