Florida CDL Air Brakes Practice Test

The Florida CDL Air Brakes test is a multiple-choice knowledge test you take for your commercial learner's permit. You need at least 80% to pass. That's the federal minimum in 49 CFR 383.135 (Florida does not publish its own number).

Last updated Oct 14, 2026. FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC.

By Scott Wilder, Editor

Last reviewed against the Florida CDL manual on October 14, 2026

Scott Wilder on X | scottwilderhq.com

FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC. It offers free exam-style practice tests built from the official CDL manual. FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.

Florida CDL permit facts

What	What Florida says	Source
Air Brakes pass mark	At least 80%. This is the federal minimum (49 CFR 383.135); Florida does not publish its own number.	Official page
Test languages	All Florida knowledge and skills tests, including CLP and CDL tests, are given only in English since February 6, 2026. Interpreters and translation are not allowed.	Official page

20 question Air Brakes practice test

1. Only the tractor of your combination has ABS. What is the benefit during braking?
1. A. The trailer can never swing out
2. B. Less chance of jackknifing and you can keep steering control
3. C. You can stop in half the distance
4. D. You do not need to watch the trailer
Show answer
Answer: B. Less chance of jackknifing and you can keep steering control
With ABS on the tractor, you should keep steering control and jackknife less.
From the official CDL manual, section 5.4.2.
2. How does an automatic air tank drain valve get rid of water and oil?
1. A. It expels them automatically
2. B. The driver must turn it every hour
3. C. It never removes water
4. D. It works only when the engine is off
Show answer
Answer: A. It expels them automatically
With an automatic drain, the water and oil are expelled automatically.
From the official CDL manual, section 5.1.4.
3. In a dual air brake system, what is the first system called?
1. A. The secondary system
2. B. The main system
3. C. The emergency system
4. D. The primary system
Show answer
Answer: D. The primary system
The first system is called the primary system and the other is the secondary system.
From the official CDL manual, section 5.2.
4. Your air brake truck has come to a normal stop. What should you do next with the transmission?
1. A. Select a starting gear
2. B. Leave it in the gear you stopped in
3. C. Turn the engine off
4. D. Shift to the highest gear
Show answer
Answer: A. Select a starting gear
The manual says that when stopped, you select a starting gear.
From the official CDL manual, section 5.4.1.
5. What can too much heat do to drum brakes?
1. A. Make them grab harder
2. B. Make them stop working
3. C. Raise the air pressure in the tanks
4. D. Make the shoes adjust themselves
Show answer
Answer: B. Make them stop working
Heat from hard or long braking can make the brakes stop working.
From the official CDL manual, section 5.1.8.
6. How may an air compressor be cooled?
1. A. By air or by the engine cooling system
2. B. By the brake fluid only
3. C. By the air tanks only
4. D. By the governor
Show answer
Answer: A. By air or by the engine cooling system
The compressor may be air cooled or cooled by the engine cooling system.
From the official CDL manual, section 5.1.1.
7. One air system of a dual brake system is very low on pressure. What is the effect?
1. A. The trailer brakes lock up as soon as you press the pedal
2. B. The spring brakes come on at full force right away
3. C. ABS takes over braking from the weak system
4. D. Front or rear brakes will not fully work, so you take longer to stop
Show answer
Answer: D. Front or rear brakes will not fully work, so you take longer to stop
A very low system means either the front or rear brakes are not fully working.
From the official CDL manual, section 5.2.
8. When you firmly apply the service brakes during your test, what should you watch for?
1. A. Only that the brake lights come on
2. B. Only that the vehicle stops in less than a second
3. C. Pulling to one side, an unusual feel, or delayed stopping
4. D. Only that the air gauge reads 125 psi
Show answer
Answer: C. Pulling to one side, an unusual feel, or delayed stopping
The test shows problems such as pulling to one side, odd pedal feel, or delayed stopping.
From the official CDL manual, section 5.3.3.
9. What two things in compressed air are bad for an air brake system?
1. A. Dust and sand
2. B. Alcohol and antifreeze
3. C. Water and compressor oil
4. D. Fuel and grease
Show answer
Answer: C. Water and compressor oil
Compressed air usually has some water and compressor oil in it, which is bad for the system.
From the official CDL manual, section 5.1.4.
10. What does an application pressure gauge show?
1. A. How much air is stored in the tanks right now
2. B. When the compressor cuts in and cuts out
3. C. How much air pressure you are applying to the brakes
4. D. How much the brake linings have worn down
Show answer
Answer: C. How much air pressure you are applying to the brakes
It shows the air pressure you apply with the brake pedal.
From the official CDL manual, section 5.1.10.
11. Where is the ABS malfunction lamp on a trailer?
1. A. On the right side, at the front or rear corner
2. B. On the roof near the front of the trailer
3. C. On the left side, at the front or rear corner
4. D. On an instrument panel at the trailer front
Show answer
Answer: C. On the left side, at the front or rear corner
Trailer ABS lamps are yellow and sit on the left side at a front or rear corner.
From the official CDL manual, section 5.1.16.
12. Your air compressor is belt-driven. What do you check on the belt during the engine compartment check?
1. A. Only that it is the same color as the other belts
2. B. Its length compared with a chart in the cab
3. C. Its condition and how tight it is
4. D. Nothing, because the governor protects the compressor
Show answer
Answer: C. Its condition and how tight it is
The manual says to check the condition and tightness of a belt-driven compressor's belt.
From the official CDL manual, section 5.3.1.
13. Why is slow air pressure buildup a danger?
1. A. The horn may stop working
2. B. The tires may go flat
3. C. The engine may overheat
4. D. Pressure may drop too low while driving, and you may need an emergency stop
Show answer
Answer: D. Pressure may drop too low while driving, and you may need an emergency stop
The manual says slow buildup may let pressure drop too low during driving.
From the official CDL manual, section 5.3.3.
14. What can happen if you keep overusing the service brakes?
1. A. The brakes grip better
2. B. The drums shrink and grab harder
3. C. Brake fade may grow until the vehicle cannot be slowed or stopped
4. D. Nothing, brakes are made for constant use
Show answer
Answer: C. Brake fade may grow until the vehicle cannot be slowed or stopped
Continued overuse may increase brake fade until the vehicle cannot be stopped.
From the official CDL manual, section 5.4.5.
15. What do you look for on the air hoses connected to the brake chambers?
1. A. Paint chips
2. B. Bright colors
3. C. Extra length
4. D. Cuts or wear from rubbing
Show answer
Answer: D. Cuts or wear from rubbing
The manual says to make sure the hoses are not cut or worn from rubbing.
From the official CDL manual, section 5.3.2.
16. Tractor and straight truck spring brakes come fully on when air pressure drops to what range?
1. A. 5 to 15 psi
2. B. 55 to 80 psi
3. C. 20 to 45 psi
4. D. 100 to 125 psi
Show answer
Answer: C. 20 to 45 psi
The manual gives a range of 20 to 45 psi, typically 20 to 30 psi.
From the official CDL manual, section 5.1.14.
17. How does a manual reset wig wag get back out of your view?
1. A. It rises out of view by itself
2. B. You must place it out of view by hand
3. C. The buzzer resets it
4. D. It resets when the engine starts
Show answer
Answer: B. You must place it out of view by hand
A manual reset wig wag must be placed in the out of view position by the driver.
From the official CDL manual, section 5.1.11.
18. Before driving a dual air brake vehicle, the compressor should build at least how much pressure in both systems?
1. A. 100 psi
2. B. 55 psi
3. C. 80 psi
4. D. 125 psi
Show answer
Answer: A. 100 psi
The manual says to build a minimum of 100 psi in both the primary and secondary systems.
From the official CDL manual, section 5.2.
19. You pull hard on a slack adjuster. Movement of more than what distance at the push rod means it probably needs adjusting?
1. A. About one quarter inch
2. B. About one inch
3. C. About three inches
4. D. About six inches
Show answer
Answer: B. About one inch
A slack adjuster that moves more than about one inch where the push rod attaches probably needs adjustment.
From the official CDL manual, section 5.3.2.
20. Tank pressure falls to about 100 psi. What does the governor do?
1. A. Keeps the compressor off until 125 psi
2. B. Lets the compressor start pumping again
3. C. Opens the safety valve
4. D. Applies the spring brakes
Show answer
Answer: B. Lets the compressor start pumping again
At the cut-in pressure of around 100 psi, the governor lets the compressor pump again.
From the official CDL manual, section 5.1.2.

Florida CDL Air Brakes questions

What score do you need to pass the Florida CDL Air Brakes test?

You need at least 80% to pass. That is the federal minimum in 49 CFR 383.135. Florida does not publish its own number.

Is the Florida CDL Air Brakes test the same as other states?

The Air Brakes test is built on the same federal knowledge standards in every state, so the topics match the CDL manual. Florida uses its own handbook: https://www.flhsmv.gov/pdf/handbooks/englishcdlhandbook.pdf

What languages is the Florida CDL knowledge test offered in?

All Florida knowledge and skills tests, including CLP and CDL tests, are given only in English since February 6, 2026. Interpreters and translation are not allowed.

Sources

https://www.ecfr.gov/current/title-49/section-383.135
https://www.flhsmv.gov/2026/01/30/flhsmv-announces-driver-license-exams-to-be-administered-in-english-only/
https://www.flhsmv.gov/pdf/handbooks/englishcdlhandbook.pdf
Manual sections used in this test: 5.1.1; 5.1.10; 5.1.11; 5.1.14; 5.1.16; 5.1.2; 5.1.4; 5.1.8; 5.2; 5.3.1; 5.3.2; 5.3.3; 5.4.1; 5.4.2; 5.4.5

Air Brakes practice test in nearby states