Free Iowa CDL Air Brakes Practice Test 2023

Do you need an Iowa Air Brakes endorsement or an L endorsement for your commercial driving license? The Iowa CDL Air Brake test 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 CDL practice test packs are based on the Iowa 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 our Iowa CDL Practice Test to get ready to pass the Iowa CDL Air Brake Test now. 

Our CDL practice tests:
Based on 2021 IA commercial driver's license manual
Full answers + detailed explanations
Perfect for first-time, renewal applicants
IA CDL Air Brakes Test format:
25 questions
20 correct answers to pass
80% passing score
List of questions
What can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus?
An air compressor can be cooled by _______.
The air brake lag distance at 55 mph on dry pavement adds about ____ feet.
In case of a low air situation, the spring brakes should come on at:
If your truck has a properly functioning dual air brake system and minimum size air tanks, the air pressure should build up from 85 to 100 psi within how many seconds?
Excessive heat caused by using your brakes too often can also cause:
In ideal conditions a truck or bus with air brakes going at 55 mph would require the stopping distance of how many feet?
Normally during anti-lock braking, the driver:
When you release the brakes and reduce the air pressure what makes up for that air loss?
What should a driver do when the low air pressure warning signal comes on?
When parking a vehicle with a modulating control valve ________.
What happens when your brake drums get very hot?
If you are driving down a steep downgrade and have reached your safe speed of 40 mph, you would apply the service brake until your speed dropped to ____ mph.
How should you check that your service brakes are working properly?
The trailer air supply knob is usually:
In order to make contact with the brake drum, the brake pads and linings are pushed outward by the:
Controlled braking is only possible _________.
If the air compressor has its own oil supply you should do what before driving?
The belt of a belt-driven air compressor should be ________.
You should use the parking brake _____________.
Vehicles with air brakes _________.
Air tanks should be drained:
What is used to put alcohol into the system and reduce ice risk?
To check the air compressor governor's "cut in" and "cut out" pressures you need to _________.
What is the purpose of a supply pressure gauge?