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Free Practice Questions for AZ CDL Air Brakes

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Key Facts: AZ CDL Air Brakes Exam

80%

Minimum passing score on the Arizona Air Brakes knowledge test

Arizona CDL Manual / 49 CFR 383.135

60 psi

Tank pressure the visible low air warning must come on above

Arizona CDL Manual Section 5.1.11

20-45 psi

Pressure range at which spring brakes come fully on

Arizona CDL Manual Section 5.1.14

32 ft

Distance air brake lag adds at 55 mph on dry pavement

Arizona CDL Manual Section 5.4.4

100 psi

Minimum pressure to build in both dual air systems before driving

Arizona CDL Manual Section 5.2

L

Restriction code for no air brake equipped CMV

49 CFR 383.95(a) / 383.153

Study Section 5 of the Arizona Commercial Driver License Manual to pass the Air Brakes knowledge test with at least 80%. Key facts: governor cut-out around 125 psi and cut-in around 100 psi, safety valve at 150 psi, low air warning before 60 psi, spring brakes at 20 to 45 psi, leakage limits of 2 psi (static) and 3 psi (applied) per minute for single vehicles, about 32 feet of brake lag at 55 mph, and braking to 5 mph below your safe speed on downgrades.

Sample AZ CDL Air Brakes Practice Questions

Try these sample questions to review concepts for the AZ CDL Air Brakes exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 217+ question experience with AI tutoring.

1Section 5 says air brakes are really three braking systems. Which one uses parts of the other two to stop the vehicle in a brake system failure?
A.The emergency brake system
B.The service brake system
C.The parking brake system
D.The engine brake system
Explanation: Section 5 says air brakes are really three different braking systems: service, parking, and emergency. The emergency brake system uses parts of the service and parking brake systems to stop the vehicle in a brake system failure.
2Which braking system applies and releases the brakes when you use the brake pedal during normal driving?
A.The parking brake system
B.The emergency brake system
C.The service brake system
D.The spring brake system
Explanation: Section 5 says the service brake system applies and releases the brakes when you use the brake pedal during normal driving.
3How is the air compressor connected to the engine, according to Section 5.1.1?
A.Through the transmission output shaft
B.By a hose from the power steering pump
C.Through an electric motor on the battery
D.Through gears or a v-belt
Explanation: Section 5.1.1 says the air compressor pumps air into the storage tanks and is connected to the engine through gears or a v-belt. It may be air cooled or cooled by the engine cooling system, and may have its own oil supply or use engine oil.
4At about what tank pressure does Section 5.1.2 say the governor stops the compressor from pumping (cut-out)?
A.Around 100 psi
B.Around 125 psi
C.Around 150 psi
D.Around 60 psi
Explanation: Section 5.1.2 says that when tank pressure rises to the cut-out level, around 125 psi, the governor stops the compressor from pumping air. When pressure falls to the cut-in level, around 100 psi, the governor lets the compressor pump again.
5Your gauge shows about 125 psi when the compressor stops pumping. You then use air until the compressor starts pumping again. According to Section 5.1.2, at about what reading should that happen?
A.About 60 psi
B.About 80 psi
C.About 110 psi
D.About 100 psi
Explanation: Section 5.1.2 says the governor stops the compressor at the cut-out level, around 125 psi, and lets it pump again when tank pressure falls to the cut-in level, around 100 psi. Always check the manufacturer's specifications.
6According to Section 5.1.3, the air storage tanks hold enough air for what?
A.To run the air horn and wipers for an entire shift
B.To hold the spring brakes on while the bus is parked
C.Several brake uses, even if the compressor stops working
D.About 50 miles of normal driving with no working compressor at all
Explanation: Section 5.1.3 says air storage tanks hold compressed air, and the tanks will hold enough air to allow the brakes to be used several times, even if the compressor stops working. The number and size of tanks varies among vehicles.
7Why does Section 5.1.4 say air tanks must be drained?
A.Water and oil collect, and water can freeze and fail the brakes
B.Draining lowers pressure so the governor can cut in sooner
C.Draining removes road dust that would clog the safety valve
D.Draining keeps the tanks from rusting through on the outside
Explanation: Section 5.1.4 says compressed air usually has some water and compressor oil in it, which is bad for the air brake system. The water can freeze in cold weather and cause brake failure, and the water and oil collect in the bottom of the tank, so drain the tanks completely.
8How is a manually operated air tank drain valve opened, according to Section 5.1.4?
A.By pressing the brake pedal five times quickly
B.By turning it a quarter turn or pulling a cable
C.By pushing in the yellow parking brake knob
D.By removing the safety valve from the first tank
Explanation: Section 5.1.4 says each air tank has a drain valve in the bottom. A manual drain is operated by turning it a quarter turn or by pulling a cable, and you must drain the tanks yourself at the end of each day of driving.
9If your vehicle does not have automatic tank drains, when does Section 5 say to drain the air tanks?
A.Once a week, during the weekly service
B.Only on days with freezing temperatures
C.At the end of each working day
D.Every 10,000 miles or at each oil change
Explanation: Section 5.1.4 says you must drain manually operated tanks yourself at the end of each day of driving, and the Section 5.4 reminders say to drain your air tanks at the end of each working day to remove moisture and oil, or the brakes could fail.
10What does Section 5.1.4 say some automatic air tank drains are equipped with?
A.Pressure gauges that take the place of the dash gauges
B.Alcohol reservoirs that refill themselves automatically
C.Timers that drain the tanks once every hour
D.Electric heating devices to keep them from freezing
Explanation: Section 5.1.4 says automatic drains expel water and oil automatically and may also be equipped for manual draining. Automatic air tanks are available with electric heating devices, which help prevent freezing of the automatic drain in cold weather.

About the AZ CDL Air Brakes Exam

The Arizona CDL Air Brakes Knowledge Test is required by ADOT MVD for drivers of commercial vehicles with air brakes, including air over hydraulic brakes. Based on Section 5 of the Arizona Commercial Driver License Manual, it covers air brake system parts, dual air systems, the seven-step inspection and final air brake check, and safe braking, including the downgrade technique and emergency stops. This free bank by OpenExamPrep offers independent practice on that material.

Exam sponsor: Arizona Department of Transportation Motor Vehicle Division (ADOT MVD). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Air brakes is not an endorsement. Arizona's Section 5 air brakes knowledge test is required if your vehicle has air brakes, including air over hydraulic brakes, and you need at least 80%. Failing it, or taking the skills test in a vehicle without air brakes, results in the L restriction (no air brake equipped CMV); testing in an air-over-hydraulic vehicle results in the Z restriction (no full air brake equipped CMV). To remove either restriction, pass the air brakes knowledge test and perform the air brake pre-trip inspection; a modified skills test may be used (49 CFR 383.135). This bank is an independent English-language multiple-choice study aid, not an official test copy or simulation.

Time Limit

not-published

Passing Score

80%

Exam / Certification Fees

No separate fee listed; CLP $25 (Class A or B) or $12.50 (Class C)

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

Air Brake System Parts

Compressor and governor (cut-out around 125 psi, cut-in around 100 psi), storage tanks and drains, alcohol evaporator, the 150-psi safety valve, foundation brakes (s-cam, wedge, disc), gauges, the low air warning before 60 psi (80 to 85 psi is common on large buses), spring brakes, parking controls, and ABS.

Manual Section 5.2

Dual Air Brake Systems

Primary (typically rear axle) and secondary (typically front axle) systems, building at least 100 psi in both before driving, the warning shut-off value above 60 psi, and what happens when one system loses pressure.

Manual Section 5.3

Inspecting Air Brake Systems

Compressor belt and slack adjuster checks, then the final air brake check: low pressure warning, applied leakage (3 psi per minute single, 4 combination), spring brake pop-out (20 to 45 psi), buildup from 85 to 100 psi within 45 seconds, static leakage (under 2 psi per minute single, 3 combination), governor cut-in and cut-out, parking brake, and service brake tests.

Manual Section 5.4

Using Air Brakes

Normal and emergency stops, braking with ABS, brake lag (about 32 feet at 55 mph; total stopping distance over 450 feet), brake fade, the five-mph-below-safe-speed downgrade technique, low air pressure, and parking brake use.

Manual Section 1.1.1; 49 CFR 383.95, 383.135, 383.153

Air Brake Licensing and Restrictions

Who must take the air brakes test (including air over hydraulic), the L (no air brakes) and Z (no full air brakes) restrictions, removing a restriction, the 80% passing score, and next-business-day retests.

Preparing for the AZ CDL Air Brakes Exam

What You Need to Know

  • Passing score: 80%
  • Assessment: Air brakes is not an endorsement. Arizona's Section 5 air brakes knowledge test is required if your vehicle has air brakes, including air over hydraulic brakes, and you need at least 80%. Failing it, or taking the skills test in a vehicle without air brakes, results in the L restriction (no air brake equipped CMV); testing in an air-over-hydraulic vehicle results in the Z restriction (no full air brake equipped CMV). To remove either restriction, pass the air brakes knowledge test and perform the air brake pre-trip inspection; a modified skills test may be used (49 CFR 383.135). This bank is an independent English-language multiple-choice study aid, not an official test copy or simulation.
  • Time limit: not-published
  • Exam / certification fees: No separate fee listed; CLP $25 (Class A or B) or $12.50 (Class C) Official sources

Using Our Practice Resources

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AZ CDL Air Brakes: Suggested Study Strategy

1Memorize the key pressures: governor cut-out around 125 psi, cut-in around 100 psi, safety valve 150 psi, low air warning before 60 psi, and spring brakes at 20 to 45 psi.
2Remember the single-vehicle leakage limits: less than 2 psi per minute static and no more than 3 psi per minute applied.
3Understand brake lag: air takes one half second or more to reach the brakes, adding about 32 feet of stopping distance at 55 mph.
4Master the downgrade technique: in the proper low gear, brake until speed is about 5 mph below your safe speed (about 3 seconds), release, and repeat when speed returns to the safe speed.

Frequently Asked Questions

Is Air Brakes an endorsement on an Arizona CDL?

No. Air brakes is a knowledge test and a skills-test check, not an endorsement. If you fail the air brakes knowledge test or take the skills test in a vehicle without air brakes, your CLP or CDL carries the L restriction (no air brake equipped CMV); testing in a vehicle with air over hydraulic brakes brings the Z restriction (no full air brake equipped CMV).

What is the low air pressure warning threshold in the Arizona CDL Manual?

Section 5.1.11 of the Arizona CDL Manual says a visible low air pressure warning must come on before air pressure in the tanks falls below 60 psi (or one half the governor cutout pressure on older vehicles). The manual adds that on large buses it is common for low pressure warning devices to signal at 80 to 85 psi.

What are the acceptable air leakage rates during the pre-trip inspection?

With a fully charged system, the engine off, and the parking brake released (static test), the loss should be less than 2 psi in one minute for a single vehicle and less than 3 psi for a combination. With the foot brake fully applied (applied test), the loss is too much if it exceeds 3 psi in one minute for a single vehicle or 4 psi for a combination.

Is this practice test an official ADOT MVD examination?

No. This is independent practice by OpenExamPrep, written in English multiple-choice format from Section 5 of the Arizona Commercial Driver License Manual and federal CDL restriction rules. It is a study aid, not an official ADOT MVD test copy or simulation, and it does not replace the air brake skills check.