# Free Colorado CDL Air Brakes Practice Test 2023

Do you need an 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 Colorado CDL practice test questions are based on the Colorado 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 with our free CDL Practice Test to get ready to pass the Colorado CDL Air Brake Test now.

Our CDL practice tests:
Based on 2021 CO commercial driver's license manual
Perfect for first-time, renewal applicants
CO CDL Air Brakes Test format:
25 questions
80% passing score
List of questions
1.
The air compressor stops pumping air at what psi?
2.
What can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus?
3.
When inspecting air brakes:
4.
An air compressor can be cooled by _______.
5.
The spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below ___ psi.
6.
The brake system that applies and releases the brakes when the driver uses the brake pedal is the ________ brake system.
7.
In ideal conditions a truck or bus with air brakes going at 55 mph would require the stopping distance of how many feet?
8.
When the engine is off and the parking brake released, a single vehicle air loss rate should be less than ________ psi in one minute.
9.
Where is the modulating control valve located on some vehicles?
10.
Some vehicles are equipped with a control allowing you to apply the spring brakes gradually, called a:
11.
What happens when your brake drums get very hot?
12.
13.
If the low air pressure warning light comes on, you should:
14.
15.
What tells the driver how much air pressure is in the air tanks?
16.
Compared to hydraulic brakes, air brakes add how much distance to an average 55 mph stop?
17.
Why does a heavily loaded vehicle need a longer distance to stop?
18.
The most common type of foundation brake is?
19.
The air tanks must be drained because:
20.
When driving an older vehicle that has a manual front brake limiting valve, drivers should:
21.
Initial air leakage rate for combination vehicles should be:
22.
Stab braking should only be used:
23.
If the air compressor has its own oil supply you should do what before driving?
24.
A warning to drivers behind you that the air brakes have been applied is the:
25.
The warning light and buzzer will come on when the air pressure in either system drops below what psi?