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. If driving a vehicle with a manual transmission, you can prevent your vehicle from rolling backward when starting from a stop by:

Explanation
To prevent rolling backward when starting from a stop, you should partly engage the clutch before removing your foot from the brake. Apply the parking brake whenever necessary to prevent your vehicle from rolling back.

2. If an approaching driver is using their high beam headlights, you should:

Explanation
If a vehicle is coming toward you while using its high beam headlights, glance away from the headlights and toward the right side of the road until the vehicle has passed. This will keep you from being blinded by the lights.

3. Hydraulic brakes can fail for one of two reasons. Which of the following is one of those reasons?

Explanation
Most hydraulic brake failures occur for one of two reasons. A first likely cause of brake failure is that the brakes have been overused on a downgrade, causing them to fade. The second likely cause is that there has been a loss of hydraulic pressure in the braking system. Brakes kept in good condition will rarely fail, but you should know which steps to take in case they do.

4. Starting in which year were newly manufactured trailers required to have ABS?

Explanation
All trailers and converter dollies manufactured on or after March 1, 1998 must be equipped with Anti-Lock Braking Systems (ABS).

5. An Anti-Lock Braking System (ABS):

Explanation
The function of an Anti-Lock Braking System (ABS) is to prevent a vehicle's wheels from locking up during hard braking.

6. Proper coupling technique:

Explanation
Knowing proper coupling and uncoupling technique is fundamental to the safe operation of combination vehicles. Improper coupling can be very dangerous.

7. Which of the following is not an indication of damaged brakes?

Explanation
Potential problems to check for when inspecting brakes include cracked drums; shoes or pads with oil, grease, or brake fluid on them; and shoes that are missing, broken, or worn dangerously thin.
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