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200+ Free Colorado CDL Air Brakes Practice Questions

Pass your Colorado CDL Air Brakes Knowledge Test exam on the first try — instant access, no signup required.

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What does the air pressure gauge tell the driver?

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Key Facts: Colorado CDL Air Brakes Exam

80%

Minimum federal CDL knowledge-test passing score

49 CFR Section 383.135

55 psi

Colorado CDL Manual low-air warning threshold before pressure drops below this value

Colorado CDL Manual Section 5

20-45 psi

Common spring-brake pop-out range

Colorado CDL Manual Section 5

$19.00

Colorado commercial learner permit fee

Colorado DMV State Fees

14 days

Colorado CLP holding period before CDL skills test

Colorado DMV CDL General Information

Colorado CDL applicants who want to operate CMVs with air brakes should study Colorado CDL Manual Section 5 and pass the Air Brakes knowledge test with at least 80% correct. Federal rules require an air-brake restriction if an applicant fails the air brake knowledge portion or skills-tests in a vehicle without air brakes. Colorado lists a one-year nonrenewable CLP, a 14-calendar-day CLP holding period before skills testing, a $19.00 CLP fee, a $17.50 CDL fee, and an $11.50 written retest fee if applicable.

Sample Colorado CDL Air Brakes Practice Questions

Try these sample questions to test your Colorado CDL Air Brakes exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 200+ question experience with AI tutoring.

1What component compresses air for the air brake system?
A.The air dryer
B.The air compressor
C.The brake chamber
D.The slack adjuster
Explanation: The air compressor pumps air into the air storage tanks. It is driven by the engine, either through belts or directly. The air dryer removes moisture from the compressed air, the brake chamber converts air pressure into mechanical force at each wheel, and the slack adjuster transfers that force to the S-cam.
2What is the typical air compressor governor cut-out pressure range?
A.60 to 80 psi
B.100 to 125 psi
C.125 to 140 psi
D.150 to 175 psi
Explanation: The governor cuts out the compressor (stops pumping) at about 125 to 140 psi. It cuts back in (resumes pumping) at about 100 to 125 psi. This pressure range keeps the system safely above the low-pressure warning threshold of 60 psi while preventing over-pressurization.
3At what pressure does the air compressor governor typically cut IN to resume pumping?
A.60 to 80 psi
B.100 to 125 psi
C.125 to 140 psi
D.145 to 150 psi
Explanation: The governor typically cuts in at 100 to 125 psi, signaling the compressor to resume pumping. It cuts out at 125 to 140 psi when system pressure is sufficient. Together these limits maintain a safe operating range well above the 60 psi low-pressure warning.
4What is the purpose of the air dryer in the brake system?
A.To cool the air before storage
B.To remove moisture and oil before air reaches the tanks
C.To increase compressed air pressure
D.To warn the driver of low pressure
Explanation: The air dryer uses a desiccant cartridge to remove water vapor and oil from compressed air before it enters the storage tanks. Removing moisture prevents corrosion, contamination of brake components, and dangerous freezing of air lines in cold weather.
5What is the function of the wet tank (supply or service reservoir)?
A.It cools brake fluid
B.It is the first storage tank where moisture collects before air moves to the other tanks
C.It supplies air only to the trailer
D.It activates the parking brakes
Explanation: The wet tank is the first storage reservoir downstream of the compressor. Most moisture and oil that gets past the air dryer settles there before clean air moves on to the primary and secondary tanks. Drivers must drain the wet tank daily to prevent contamination of the rest of the system.
6At what pressure does the safety valve in the supply tank typically open to release excess air?
A.100 psi
B.125 psi
C.150 psi
D.200 psi
Explanation: The safety valve, installed in the supply (wet) tank, is set to open at about 150 psi. It is a backup that protects the system if the governor fails to cut out the compressor. If the valve releases, the compressor or governor needs immediate repair.
7What is the role of the foot valve (also called the treadle or service brake valve)?
A.It locks the parking brake
B.It supplies air to the brake chambers in proportion to how hard the driver presses the pedal
C.It drains water from the tanks
D.It controls the trailer air supply
Explanation: The foot valve (treadle valve) meters air to the brake chambers in proportion to how far the driver depresses the brake pedal. Pressing harder sends more air, applying more braking force. Releasing the pedal exhausts air from the chambers, allowing the springs and slack adjusters to release the brakes.
8What does the brake chamber do?
A.Stores compressed air for emergencies
B.Converts air pressure into mechanical force through a pushrod
C.Cools brake drums during use
D.Acts as a backup for the parking brake
Explanation: A brake chamber is a sealed housing with a diaphragm or piston. When air pressure enters, the diaphragm pushes a pushrod outward. The pushrod rotates the slack adjuster and S-cam, which forces the brake shoes against the drum to apply braking force.
9What is the role of the slack adjuster on an S-cam brake?
A.It cushions the impact of hard braking
B.It transfers force from the pushrod to the S-cam and can be adjusted to compensate for lining wear
C.It bleeds water from the system
D.It limits maximum air pressure
Explanation: The slack adjuster is a lever that connects the brake chamber pushrod to the S-cam. As the pushrod extends, the slack adjuster rotates the S-cam, which pushes the brake shoes against the drum. It can be adjusted to maintain proper pushrod travel as brake linings wear.
10What does the S-cam do in an S-cam drum brake?
A.It releases air from the lines
B.It rotates between the brake shoes, forcing them outward against the drum
C.It cools the brake drum
D.It activates the low-pressure warning
Explanation: The S-cam is an S-shaped piece of steel between the two brake shoes. When the slack adjuster rotates it, the wide part of the S forces the shoes outward against the drum, creating friction and slowing the wheel. When air pressure is released, return springs pull the shoes back and rotate the S-cam to its original position.

About the Colorado CDL Air Brakes Exam

The Colorado CDL Air Brakes Knowledge Test checks whether a commercial driver applicant understands air brake components, dual air systems, required inspection checks, low-air warnings, spring brakes, ABS behavior, brake lag, emergency stopping methods, brake fade, downgrade braking, parking brake use, and federal air-brake restriction rules. Colorado directs drivers to the Colorado Commercial Driver License Manual, whose Section 5 is dedicated to air brakes, and Colorado CDL applicants must also follow Colorado DMV CLP, medical, ELDT, fee, and skills-testing requirements.

Assessment

State-administered multiple-choice CDL knowledge test covering Colorado CDL Manual Section 5 air brake system parts, dual air brake systems, air brake inspection, and safe air brake use.

Time Limit

State-administered computer knowledge test; Colorado DMV does not publish a separate Air Brakes time limit on its CDL information page

Passing Score

80% minimum on each CDL knowledge test under 49 CFR Section 383.135

Exam Fee

$19.00 Colorado commercial learner permit; $17.50 Commercial Driver's License; $11.50 written retest fee if applicable (Colorado Division of Motor Vehicles under FMCSA CDL standards)

Colorado CDL Air Brakes Exam Content Outline

22%

Air Brake System Parts

Air compressor, governor, tanks, tank drains, alcohol evaporator, safety valve, gauges, brake chambers, S-cam, wedge and disc brakes, brake light switch, spring brakes, ABS, and front brake limiting valves.

16%

Dual Air Brake Systems

Primary and secondary systems, separate tanks and lines, gauge monitoring, minimum 100 psi before driving, low-air warning behavior, and safe response when one side is low.

30%

Air Brake Inspection

Compressor governor cut-in/cut-out, applied air leakage, low-pressure warning, spring-brake pop-out, pressure buildup, parking brake test, service brake test, slack adjusters, drums, linings, hoses, and automatic adjuster cautions.

24%

Using Air Brakes Safely

Normal stops, ABS, emergency controlled braking, stab braking, brake lag, stopping-distance factors, brake fade, downgrade braking, low-air response, hot/wet parking brake cautions, and wheel chocking.

8%

Colorado and Federal CDL Rules

Colorado CLP validity, 14-day hold, fees, knowledge-test language availability, FMCSA air-brake restriction rules, and 80% federal knowledge-test passing standard.

How to Pass the Colorado CDL Air Brakes Exam

What You Need to Know

  • Passing score: 80% minimum on each CDL knowledge test under 49 CFR Section 383.135
  • Assessment: State-administered multiple-choice CDL knowledge test covering Colorado CDL Manual Section 5 air brake system parts, dual air brake systems, air brake inspection, and safe air brake use.
  • Time limit: State-administered computer knowledge test; Colorado DMV does not publish a separate Air Brakes time limit on its CDL information page
  • Exam fee: $19.00 Colorado commercial learner permit; $17.50 Commercial Driver's License; $11.50 written retest fee if applicable

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

Colorado CDL Air Brakes Study Tips from Top Performers

1Read Colorado CDL Manual Section 5 once for concepts, then reread the inspection and using-air-brakes subsections for exact procedures.
2Memorize the pressure numbers: about 100 psi cut-in, about 125 psi cut-out, low-air warning before 55 psi, spring brakes at 20-45 psi, and 85-to-100 psi buildup within 45 seconds for dual systems.
3Practice explaining the final air brake check aloud: governor, applied leakage, low-air warning, spring-brake pop-out, pressure buildup, parking brake, and service brake.
4Treat automatic slack adjusters as inspectable safety components; excessive pushrod stroke means a repair issue, not a routine manual-adjustment habit.
5For mountain driving, connect brake fade prevention to Colorado driving realities: choose the low gear before the downgrade and use service brakes as a supplement to engine braking.
6Review 49 CFR Sections 383.95 and 383.135 so you understand the air-brake restriction and 80% passing-score rules.

Frequently Asked Questions

What score do I need to pass the Colorado CDL Air Brakes knowledge test?

Federal CDL rules require at least 80% correct on each CDL knowledge test, including air brakes.

What happens if I fail the air brake knowledge portion?

Under 49 CFR Sections 383.135 and 383.95, if a CLP or CDL is issued after failing the air brake knowledge portion, an air-brake restriction must be indicated.

What official manual section should I study?

Study Section 5, Air Brakes, of the Colorado Commercial Driver License Manual. If pulling a trailer with air brakes, also review the relevant air-brake context in Section 6.

How long is a Colorado CLP valid?

Colorado DMV states a Commercial Learner Permit is valid for one year and is not eligible for renewal.

How much does the Colorado CLP cost?

Colorado DMV State Fees lists a Commercial Driver License instruction permit at $19.00, the CDL at $17.50, and the driving knowledge written retest fee at $11.50 if applicable.