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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
Full answers + detailed explanations
Perfect for first-time, renewal applicants
DC CDL Air Brakes Test format:
25 questions
20 correct answers to pass
80% passing score
Study now
List of questions
1.
"A slack adjuster’s free play needs to be adjusted if it is more than about ______ when you pull hard on it."
2.
A low air pressure warning signal is ________.
3.
Under normal conditions, in order to engage the parking brakes the driver should:
4.
Emergency stab braking is:
5.
Brake fade is caused by:
6.
Normally during anti-lock braking, the driver _____.
7.
Another name for the brake pedal is the "foot valve", or:
8.
When stab braking if you re-apply the brakes before the wheels start rolling, __________.
9.
The safety valve is set automatically when pressure is:
10.
The parking brake knob is usually:
11.
If your truck has a dual air brake system, and one of the systems is low on pressure:
12.
The trailer air supply knob is usually:
13.
In case of emergency stops, drivers should:
14.
Compared to hydraulic brakes, air brakes add how much distance to an average 55 mph stop?
15.
If you need to make an emergency stop, you should brake so that you can ________.
16.
Brake drums should not have cracks longer than what length?
17.
At minimum, a dual air system should build up to what psi in the primary and secondary systems?
18.
When driving an older vehicle that has a manual front brake limiting valve, drivers should:
19.
Why do air brakes take longer to stop than hydraulic brakes?
20.
The belt of a belt-driven air compressor should be ________.
21.
What is proper braking technique for drivers travelling down a hill or any other downgrade?
22.
To avoid damaging the brakes, what should you never do while the spring brakes are applied?
23.
Vehicles without automatic air tank drains need to be checked manually to remove ________?
24.
Typically, at what psi does the air compressor governor stop the compressor from pumping air?
25.
What is the purpose of an air storage tank?
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