# Free Colorado CDL Air Brakes Practice Test 2023

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.
Air tanks need to be drained ______.
2.
The proper use of the brakes when going down a long steep grade after selecting a proper gear is to brake until your speed is about ____ below the posted speed and release your brake.
3.
To test the vehicle's service brakes, move the vehicle:
4.
A mechanical device that drops a low air warning into a drivers view is called a:
5.
Excessive heat caused by using your brakes too often can also cause:
6.
If your vehicle has an alcohol evaporator, it is there to:
7.
In a controlled braking emergency:
8.
9.
Spring brakes will generally come on at:
10.
While applying the brakes, what tells the driver how much air pressure is being used?
11.
When the air system is low ________.
12.
When should the spring brakes activate?
13.
When your brake's main air pressure is lost ________.
14.
What is a \"Wig Wag\"
15.
All of the following are factors in total stopping distance except:
16.
17.
Under normal braking conditions, the vehicle:
18.
The most common problem found in roadside inspections is:
19.
Pushing the brake pedal down harder __________.
20.
In dual air systems, how long should it take air pressure to build 85 to 100 psi?
21.
In a dual air brake system, if the air pressure in one part of the system drops enough to set off the low air warning:
22.
The braking power of the spring brakes ______.
23.
Brake drums or discs _______.
24.
Spring brakes are applied:
25.
Vehicles without automatic air tank drains need to be checked manually to remove ________?