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. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Illinois Commercial Driver’s License Study Guide. Questions come from chapters covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.
Number of Question
Passing Score
19. Do not use the parking brake when parking if:
Explanation
A parking brake should not be used if the vehicle's brakes are very hot from use on a steep downgrade or if the brakes are very wet and temperatures are freezing. Using the parking brake when brakes are hot could cause damage to the brakes, and using the brakes when they are wet in freezing weather may cause the brakes to ice up, rendering the vehicle immobile.
20. The emergency brake system uses:
Explanation
In an air brake system, there are three different braking systems: a service brake system, a parking brake system, and an emergency brake system. The emergency brake system uses parts of both the parking and service brake systems.
21. A vehicle equipped with an Anti-Lock Braking System (ABS) uses a ____ light to warn that the system is not working properly.
Explanation
Anti-Lock Braking System (ABS) malfunction lamps are usually yellow. Even if the ABS isn't working properly, a driver will still have access to the vehicle's usual braking functions.
22. A tank endorsement is:
Explanation
Subject to certain conditions, a tank endorsement is required to operate a tank vehicle that is used to haul either liquids or gases.
23. The ____ tells a driver how much pressure is in the air tanks.
Explanation
A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.
24. If braking at a speed of 55 mph while driving on dry pavement, the brake lag can add ____ to your vehicle's total stopping distance.
Explanation
The total stopping distance for vehicles equipped with air brakes is made up of four factors: perception distance, reaction distance, brake lag distance, and braking distance. When braking at a speed of 55 mph while driving on dry pavement, the brake lag can add around 32 feet to a vehicle's total stopping distance.
25. When the spring brakes are activated in a vehicle with air brakes, you should never:
Explanation
