Instructions

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.. Read More

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 or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the South Dakota 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 25

Passing Score 20

1. Anti-Lock Braking Systems (ABS):

Reduce a vehicle's normal braking capacity.

Are in addition to other braking systems and do not reduce a vehicle's braking power.

Are not effective on larger vehicles.

If equipped, ABS is in addition to a vehicle's normal braking system and does not increase or decrease the braking power of any other system. ABS only activates when a vehicle's wheels are about to lock.

2. On a truck with air brakes, the braking system’s air compressor:

Pumps air into the air storage tanks.

Fills the tires.

Moves air to the back of the truck.

Cleans the brakes.

In an air brake system, the air compressor pumps air into the air storage tanks. The air compressor is controlled by the air compressor governor.

3. Alcohol evaporators are:

Illegal.

Used to add alcohol to braking systems to prevent items from freezing.

Only allowed on vehicles carrying hazardous materials.

Some air brake systems include an alcohol evaporator. The evaporator introduces alcohol into the braking system to prevent the formation of ice, which can cause damage.

4. Air pressure should build up in a single air system within:

15 minutes.

12 minutes.

Three minutes.

One minute.

In a vehicle with a single air brake system, after the engine is at operating rpms, the pressure in the air system should generally build from 50 to 90 psi within three minutes.

5. In a dual air brake system:

Air tanks are shared by both systems.

Each system has its own air tanks.

You must designate which system you are using.

Brakes on only one side of the vehicle will work.

Most heavy-duty vehicles use dual air brake systems. A dual air brake system consists of two separate air brake systems, connected by a single set of brake controls. Each system has its own air tanks.

6. Air tank drains:

Allow rain water to enter air tanks.

Are used to drain water and oil from air tanks.

Should never be opened.

Must remain open while driving.

In an air brake system, the air tanks are equipped with drains that allow water and compressor oil to be removed from the system. If allowed to build up, water and compressor oil can damage an air brake system.

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