# Free District of Columbia CDL Air Brakes Practice Test 2023

Do you need an Air Brakes endorsement or an L endorsement for your commercial driving license? The District of Columbia 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 DC CDL practice test questions are relevant, all of them are based on the DC 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 CDL practice test to get ready to pass the District of Columbia CDL Air Brake Test now.

Our CDL practice tests:
Based on 2021 DC commercial driver's license manual
Perfect for first-time, renewal applicants
DC CDL Air Brakes Test format:
25 questions
80% passing score
List of questions
1.
If you do not have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks?
2.
The air brake lag distance at 55 mph on dry pavement adds about ____ feet.
3.
Excessive use of the service brakes results in overheating which can lead to:
4.
Air tanks need to be drained ______.
5.
A mechanical device that drops a low air warning into a drivers view is called a:
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 air system is low ________.
9.
When you need to depress the brakes harder and harder just to maintain the same speed this means ______.
10.
What type of brakes pushes a wedge between the ends of two brake shoes to stop the vehicle?
11.
When does the air compressor governor allow air to start pumping?
12.
If the air compressor should develop a leak, what keeps the air in the tanks?
13.
When checking the air pressure buildup, pressure should build:
14.
15.
The emergency spring brake release knob is:
16.
A device that limits the amount of air provided to the front brakes is a:
17.
Repeatedly partially increasing and pressing the brake pedal may result in:
18.
With air brake vehicles, the parking brakes should be used:
19.
The most common type of foundation brake is?
20.
Why should you check the brake adjustment often?
21.
Brake linings should not be _______.
22.
Spring brakes are applied:
23.
The parking brake should be used _________.
24.
What does ABS stand for?
25.
Vehicles with air brakes have pressure gauges connected to the _______.