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 four possible answer choices. Test questions come from the Colorado Commercial Driver License 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. Trailers manufactured after ____ must be equipped with Anti-Lock Braking Systems (ABS).

Explanation
Trailers and converter dollies manufactured on or after March 1, 1998 are required to have Anti-Lock Braking Systems (ABS).

2. If the brakes “pull” to one side or the other when you use them, it's a sign that:

Explanation
If your vehicle "pulls" to one side when braking, you may have brake trouble. If there is an issue with your brakes, you should fix the issue before driving. Operating an unsafe vehicle is against federal and state laws.

3. 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.

4. Which of the following is not a part of an air brake system?

Explanation
Air brakes consists of three separate braking systems: the service brake system, the parking brake system, and the emergency brake system.

5. 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.

6. When a vehicle is started, warning lights and buzzers:

Explanation
After an engine is started, the warning lights and buzzers for oil, coolant, charging circuits, and the Anti-Lock Braking System (ABS) should go out right away.

7. When driving a double or triple, it is important to remember that:

Explanation
Doubles and triples need more space than other vehicles, both because they are longer than other vehicles and because their size and weight prevent them from turning or stopping suddenly. When driving a double or triple, always make sure you have enough space before entering traffic, crossing traffic, or changing lanes.
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