# 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.
The most common type of foundation brakes are:
2.
An application pressure gauge shows how much air you are applying to the brakes. Increased application pressure to maintain the same speed indicates that __________.
3.
All air brake equipped vehicles have:
4.
The air brake lag distance at 55 mph on dry pavement adds about ____ feet.
5.
The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks falls below ____ psi.
6.
Parking or emergency brakes of trucks and buses can be legally held on by ____ pressure.
7.
The most important thing to do when a low air pressure warning comes on is:
8.
An air brake system is fully charged at what psi?
9.
On a long or steep downgrade, the foot brakes should be used _______.
10.
What negatively affects the braking power of a spring brake?
11.
When the mechanical arm of a wig wag drops into your view that means the pressure in your system has dropped below what psi?
12.
Which braking system applies and releases the parking brakes when you use the parking brake control?
13.
What type of brakes pushes a wedge between the ends of two brake shoes to stop the vehicle?
14.
If the low air warning comes on while you are driving, you should:
15.
When brakes are applied, the brake shoes will press against the:
16.
After the initial pressure drop, air leakage for single vehicles should be less than:
17.
Besides heat, another cause of brake fade is:
18.
In a dual air brake system, the first system, supplying the rear brakes, is commonly known as the "primary" system, and the other as the:
19.
After the initial pressure drop, air leakage for combination vehicles should be less than:
20.
If you need to make an emergency stop, you should brake so that you can ________.
21.
The air compressor is connected to the engine through ______.
22.
How are brakes designed?
23.
The safety valve in the air compressor tank is set to open at _____.
24.
The parking brake should be used _________.
25.
What brake system uses part of the service and parking brake systems to stop the vehicle in the event of a brake system failure?