Air Brakes
This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice questions. Each question has three answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Iowa Commercial Driver License Manual. Questions come from the chapter covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.
Number of Question
Passing Score
1. If you are driving and the ABS light comes on, it means that the ABS:
Explanation
ABS malfunction lamps indicate that something in the Anti-Lock Braking System is not working properly.
2. If the low air pressure warning signal comes on in a vehicle with air brakes, the driver should:
Explanation
If the low air pressure warning signal comes on while you are operating a vehicle with air brakes, you should stop and safely park the vehicle as soon as possible. It is essential that you are able to stop safely while you still have some braking power remaining.
3. In a dual air brake system:
Explanation
There are two air brake systems in a dual air brake system. The systems share a set of brake controls, but each system has its own tanks, hoses, and lines.
4. How much distance will an air brake-equipped vehicle need to come to a complete stop if it is traveling at 55 mph under ideal driving conditions?
Explanation
A vehicle's total stopping distance is made up of perception distance, reaction distance, brake lag distance, and braking distance. With all of these factors included, an air brake-equipped vehicle traveling at a speed of 55 mph under ideal driving conditions will need approximately 450 feet to come to a complete stop.
5. To make a stop in a vehicle equipped with air brakes, the driver should:
Explanation
To make a normal stop in a vehicle that is equipped with air brakes, you should simply press the brake pedal down.
6. Brakes out of adjustment will:
Explanation
