# Free Illinois CDL Air Brakes Practice Test 2023

Do you need an Illinois Air Brakes endorsement or an L endorsement for your commercial driving license? The CDL Air Brake has some differences from other endorsements because your license will receive a mark of restriction if you fail the test. So having good preparation before exam day is very necessary. To ensure that our questions are relevant, all of our CDL practice test packs are based on the Illinois CDL manual. Each question has a detailed explanation for you to thoroughly learn the format and the topic. Don't be afraid of having a restriction on your license. Let’s try our Illinois CDL Practice Test to get ready to pass the Illinois CDL Air Brake Test now.

Our CDL practice tests:
Based on 2021 IL commercial driver's license manual
Perfect for first-time, renewal applicants
IL CDL Air Brakes Test format:
25 questions
80% passing score
List of questions
1.
A driver needs to be able to see a warning when the air pressure in the service air tanks falls below ______.
2.
The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like:
3.
The reduced stopping power caused by overuse of the service brakes and excessive heat is called:
4.
Total stopping distance for air brakes is longer than that for hydraulic brakes due to ______ distance.
5.
Why drain water from compressed air tanks?
6.
The supply pressure gauge shows how much pressure:
7.
Spring brakes will generally come on at:
8.
Where is the modulating control valve located on some vehicles?
9.
10.
When checking the low pressure warning signal, it should turn on before the pressure drops below what psi?
11.
In most newer vehicles, the parking brake control will be:
12.
The parking brake knob is usually:
13.
Air braking takes more time than hydraulic braking because:
14.
What must the air pressure be, at minimum, in both parts of a dual air brake system?
15.
The emergency spring brake release knob is:
16.
If your vehicle has an alcohol evaporator, every day during cold weather you should:
17.
In order to make contact with the brake drum, the brake pads and linings are pushed outward by the:
18.
All of the following apply if the low air pressure warning signal does not work except:
19.
Controlled braking is only possible _________.
20.
If you need to make an emergency stop, you should brake so that you can ________.
21.
When driving an older vehicle that has a manual front brake limiting valve, drivers should:
22.
On newer vehicles, the parking brake control knob is typically yellow, but on older vehicles, the parking brake might be what color?
23.
What is proper braking technique for drivers travelling down a hill or any other downgrade?
24.
Vehicles without automatic air tank drains need to be checked manually to remove ________?
25.
Vehicles with air brakes have pressure gauges connected to the _______.