Air Brakes Endorsement Test | Illinois 2026 #2

Train for FREE online with our Illinois CDL air brake test. The official exam test consists of several obligatory parts, with all of them checking your knowledge of different blocks of road rules. If you need to obtain a IL Class A/Class B driver license in 2026, practice as much as possible. Free sample tests published on our website will help you check and improve your knowledge and boost your grades. Please bear in mind that the requirements for CDL may vary from state to state.

Number of Question 25

Passing Score 20

Number of Tests 20

1 . The safety valve located on the first tank opens:

Regularly.

If there is too little pressure.

If there is too much pressure.

After every stop.

In an air brake system, the first tank that receives compressed air has a safety valve that releases air if the pressure gets too high. It is usually set to open at 150 psi. If the valve must open, there is a fault in the system that should be repaired by a mechanic.

2 . In a newer vehicle, you apply the parking brake:

By using a diamond-shaped yellow knob.

By using a round red knob.

By using a square green knob.

By using a black round knob.

In a newer vehicle with air brakes, the parking brake is controlled by a diamond-shaped yellow knob. The knob is pulled out to apply the parking brakes and pushed in to release them.

3 . When traveling down a steep downgrade, the best way to use your brakes is to:

Ride the brakes all the way down the hill.

Apply the brakes for a few seconds, then release the brakes for a few seconds. Continue to repeat these steps as you travel down the hill.

Apply the brakes only near the bottom of the downgrade.

Apply consistent pressure to the brake pedal all the way down the hill.

On a long or steep downgrade, brakes should only be used to supplement the braking effect of the engine. Apply the brakes just enough to feel a definite slowing down, then release them once you are about 5 mph below your target "safe" speed. Once your vehicle reaches its safe speed again, repeat this process.

4 . Most heavy-duty vehicles use:

Single air brake systems.

Dual air brake systems.

Triple air brake systems.

Quadruple air brake systems.

Most heavy-duty vehicles use dual air brake systems, in which there are two separate braking systems operated by a single set of controls. Each system operates the brakes on different axles.

5 . Vehicles with dual air brake systems:

Have air pressure in the braking system even when the vehicle is not running.

Maintain some air pressure in the braking system when the vehicle is not running.

Must be run to build air pressure to allow the brakes to operate properly.

Maintain air pressure when shut off for periods of less than four hours.

Before driving a vehicle with a dual air brake system, allow time for the air compressor to build up pressure of at least 100 psi in both the primary and secondary systems.

6 . The ____ tells a driver how much pressure is in the air tanks.

Application pressure gauge

Air compressor governor

Supply pressure gauge

Drum brake

A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.

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2026 Illinois | Frequently Asked Questions

To secure a CDL Bus endorsement in Illinois, you must first possess a Commercial Driver's License (CDL). Then, pass a passenger endorsement test which covers topics like bus inspection, loading/unloading passengers, and emergency procedures. Additionally, you may need to pass a skills test in the type of bus you wish to drive.

To obtain a CDL Bus license in Illinois, you must be at least 21 years old, have a valid Illinois driver's license, and pass a vision test. You will need to pass both a written and skills test for the Commercial Driver's License (CDL). For the bus endorsement, you must pass the Passenger Vehicles written test and perform a driving test.

Yes, specific training is necessary for a CDL Bus endorsement. You need to pass a written passenger endorsement test and a skills test in the type of bus you wish to drive. Some individuals may require additional training depending on their experience level, including hands-on driving practice and understanding safety regulations.

CDL Bus licenses in Illinois fall into three classifications: Class A, B, and C. Class A is for vehicles with a combined weight over 26,001 lbs. where the towed vehicle is over 10,000 lbs. Class B is for single vehicles over 26,001 lbs. or towing another vehicle not over 10,000 lbs. Class C is for vehicles designed to transport 16 or more passengers including the driver.

No, you cannot use your personal vehicle for the CDL Bus driving test. The vehicle used for the test must match the type and class of CDL you're applying for. For a bus endorsement, you must take the test in the type of bus you plan to drive. This ensures you can handle and operate that specific vehicle safely.

During the CDL Bus driving test, you are evaluated on specific skills like pre-trip vehicle inspection, basic vehicle control, and on-road driving. These may include maneuvers like backing up, parallel parking, making turns, and highway driving. You will also be evaluated on your ability to handle bus-specific situations like loading and unloading passengers safely.

Yes, there are additional medical prerequisites for a CDL Bus endorsement. You must pass a Department of Transportation (DOT) physical examination every two years. The exam evaluates your vision, hearing, blood pressure, and checks for diabetes and other potential health issues. You'll also need to self-certify your medical status with the Illinois Secretary of State's office.

No, it is not permissible to transport passengers without a valid CDL Bus endorsement in Illinois. This is a legal requirement, and driving a commercial passenger vehicle without the appropriate endorsement can result in significant fines, license suspension, and even jail time. It ensures the driver has the necessary skills and knowledge for passenger safety.

Yes, the CDL Bus endorsement can be added to your existing CDL in Illinois. You don't need to apply for a new CDL. However, you must pass the Passenger Transport Test and a skills test in the type of vehicle you'll be driving. Additionally, a background check is required for school bus drivers.

Yes, there are restrictions for drivers with a CDL Bus endorsement in Illinois. These include a zero-tolerance policy for alcohol and drugs, mandatory regular medical examinations to ensure fitness to drive, and adherence to hours-of-service regulations to prevent fatigue. Additionally, drivers must always wear seat belts and obey speed limits. Violations can lead to fines, license suspension, or revocation.