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 answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Maine 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. If air pressure drops to a level between ____, a visual low pressure warning signal should have already activated.

55 and 75 psi.

80 and 95 psi.

65 and 100 psi.

A visual low pressure warning signal should activate before air pressure drops to a level between 55 and 75 psi. This signal could be a light, a buzzer, or a wig wag.

2. When leaving a vehicle unattended, a driver should:

Always set the parking brake.

Only set the parking brake if the vehicle is parked on a slope.

Deflate the tires by 10 percent.

Always apply the parking brake when leaving your vehicle unattended.

3. An alcohol evaporator in an air brake system:

Makes the brakes work without squeaking.

Prevents ice from forming in the braking system.

Lubricates parts of the braking system.

Some air brake systems include an evaporator that introduces alcohol into the system. The alcohol can help prevent ice from forming within the system.

4. Vehicles equipped with Anti-Lock Braking Systems (ABS) have ____ malfunction lamps to indicate when the ABS is not working.

Green

Blue

Yellow

Vehicles with ABS have yellow malfunction lamps to alert drivers when the braking systems are not working. Be sure you know where the malfunction lamp on your vehicle is before beginning a trip.

5. The ____ are activated by an electric switch that is triggered by the brake pedal.

Headlights

Turn signals

Brake lights

In a vehicle with air brakes, the brake lights are activated when the brake pedal is pushed and air pressure moves an electric switch. With the application of air pressure, the switch will then turn on the brake lights.

6. When stopping in an emergency situation, you should:

Veer your trailer to the right and stop.

Stop in a straight line.

Veer your trailer to the left and stop.

If you need to make an emergency stop, you can use either the controlled braking method or the stab braking method. It's important to brake in a way that keeps your vehicle in a straight line but will still allow you to turn if necessary.

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