Double

This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice.. Read More

This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice questions. To pass, the applicant must answer at least 16 questions correctly. Each question has three or four possible answer choices. Test questions come from the Wisconsin Commercial Driver’s Manual. Questions come from chapters covering: Driving Safely, Air Brakes (if applicable), Combination Vehicles and Doubles and Triples. The Double/Triple endorsement can be used with the Class A CDL.

Number of Question
Passing Score

1. Pressing and releasing a brake pedal unnecessarily can:

Explanation
In an air brake system, pressing and releasing the brake pedal unnecessarily can release air from the braking system faster than the compressor can replace it.

2. The air compressor is connected to the:

Explanation
The air compressor of an air brake system is connected to the engine through gears or a v-belt. The compressor may be air-cooled or cooled by the engine cooling system.

3. If you are braking on dry pavement while traveling at 55 mph, how much distance will brake lag add to your overall 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 the vehicle's total stopping distance.

4. Air lines should be securely connected to:

Explanation
When inspecting the convertor dolly, ensure that all components are present and in proper working condition. The air lines should be securely attached to the proper glad hands and should not contain any leaks. They should be attached with enough slack to allow for easy turning.

5. Mirrors should be adjusted:

Explanation
Mirrors should be checked prior to the beginning of a trip. On a vehicle with a trailer, mirror adjustment can only be checked accurately if the connected trailer is straight.

6. Most heavy-duty vehicles use ____ air brake systems.

Explanation
The majority of heavy-duty vehicles are equipped with dual air brake systems.

7. What happens if the air pressure in a system's air tanks falls below 60 psi?

Explanation
In an air brake system, a low pressure warning signal should activate if the pressure in the air tanks falls to a level below 60 psi. This signal may be in the form of a warning light or a wig wag.
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