Air Brakes #1
Air Brakes Endorsement Test | Illinois 2026 #1 Page 4 of 4
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.
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19 . Air tank drains:
Clean the air in the passenger compartment.
In an air brake system, air tanks have drains to remove accumulations of water and compressor oil. Allowing water and oil to accumulate in the system could cause damage to the brakes. Manually operated drains should be used daily.
20 . In a vehicle with dual air brakes, what happens if one system is low on pressure?
The low system will use an auxiliary system to fill the tank.
In a dual air brake system, if one of the air systems gets very low on pressure, either the front or rear brakes will not be operating fully. You should bring your vehicle to a safe stop and have the air system repaired.
21 . You should not use the parking brake:
If your vehicle's other braking systems seem to be working adequately.
A parking brake should not be used if the vehicle's brakes are very hot from use on a steep downgrade or if the brakes are very wet and temperatures are freezing. Using the parking brake when brakes are hot could cause damage to the brakes, and using the brakes when they are wet in freezing weather may cause the brakes to ice up, rendering the vehicle immobile.
22 . In a newer vehicle, you apply the parking brake:
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.
23 . How is the parking brake released?
By tapping the accelerator twice
In newer vehicles with air brakes, the parking brakes are controlled by a diamond-shaped yellow knob. Pull the knob out to activate the parking brakes and push it in to release them.
24 . Emergency brakes:
Are optional.
All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. These brakes must be held by mechanical force.
25 . Most heavy-duty vehicles use:
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.
See the exact questions that will be on the 2026 Illinois DMV exam.
99.2% of people who use the cheat sheet pass the FIRST TIME
Lillian MCcranie explains how our CDL study guide was helpful in passing the exam and recommends it to everyone.
Cameron tells us how he purchased the CDL exam, and found it to be a useful tool which helped him pass the exam and find a job.
2026 Illinois | Frequently Asked Questions
To secure a CDL Doubles/Triples endorsement in Illinois, you must already have a CDL license. Then, study the Illinois CDL handbook's section on double/triple trailers. Afterward, schedule an endorsement test at a local Secretary of State Facility. Passing this test adds the Doubles/Triples endorsement to your CDL. Remember, driving experience with such trailers cannot replace this test.
To obtain a CDL Doubles/Triples license, you need to have a valid Commercial Driver's License (CDL). You then need to study the relevant sections in the CDL manual, specifically focusing on double and triple trailers. After studying, schedule and pass the Doubles/Triples endorsement test at your local DMV. Some states may also require proof of training or experience.
While specific requirements may vary by state, generally, you do not need specialized experience or training for a CDL Doubles/Triples endorsement. However, you must hold a valid Commercial Driver's License (CDL). You'll need to study the Doubles and Triples section of your state's CDL manual and pass the endorsement knowledge test at your local DMV.
Yes, to obtain a CDL Doubles/Triples endorsement in Illinois, you must pass an additional written test. This test covers the specific knowledge required for pulling double or triple trailers. The information for this test can be found in the specialized section of the Illinois CDL handbook. No extra road skills test is required for this endorsement.
Actually, in Illinois, there's no specific road skills test for the Doubles/Triples endorsement. The process primarily involves a written knowledge test. This test focuses on topics like coupling and uncoupling, inspecting doubles and triples, and crucial driving skills for these types of vehicles. However, practical ability to handle these vehicles safely is beneficial.
No, it's not permissible to operate double/triple trailers without a valid CDL Doubles/Triples endorsement in Illinois. Driving these types of vehicles requires specialized knowledge and skills. Therefore, you must pass the Doubles/Triples Endorsement Knowledge Test to legally operate such vehicles. Failure to do so can result in penalties, including fines and suspension of your commercial driving privileges.
You can add the Doubles/Triples endorsement to your current CDL. You do not need to initiate a new application for a CDL license. However, you'll need to pass the Doubles/Triples written knowledge test. Once you pass, the endorsement will be added to your existing CDL. Remember, each state may have specific fees for adding endorsements.
Yes, there are some limitations. A CDL Doubles/Triples endorsement allows you to operate vehicles with more than one trailer, but it doesn't permit the operation of all types of commercial vehicles. For example, you would need separate endorsements to operate a school bus, tanker vehicle, or to transport hazardous materials. Additionally, all standard CDL regulations and restrictions still apply.
In Illinois, the maximum length for a semi-trailer is 53 feet, and for each trailer in a double/triple setup, it's 28.5 feet. The gross vehicle weight limit is 80,000 lbs. However, these limits can vary depending on the type of highways and roads used. It's always best to check with local authorities or the Illinois Department of Transportation for specific restrictions.
Yes, there are specific safety guidelines. Drivers must check coupling systems regularly, maintain a safe following distance, be extra cautious in bad weather, and ensure the heaviest trailer is first. Additionally, they must comply with federal and state regulations, including hours of service rules, vehicle inspection requirements, and proper cargo securement. Remember to always prioritize safety over speed or schedule.
