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 Mississippi Professional Driver’s Manual. Questions come from chapters covering: Driving Safely, Transporting Cargo 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. Hydroplaning:

Explanation
Hydroplaning is an effect in which a vehicle's tires lose traction with the surface of the road and instead glide along a layer of water. There does not have to be a large amount of water on the road for this to occur. Hydroplaning can begin at speeds as low as 30 mph.

2. How is the parking brake released?

Explanation
In vehicles with air brakes, the parking brake is controlled by a knob. The knob is pulled out to apply the brakes, and pushed in to release them.

3. Suspension system defects may include all of the following, except:

Explanation
Defects to check for when inspecting your vehicle's suspension system include cracked or broken spring hangers; missing or broken leaves in a leaf spring; and leaking shock absorbers. If you spot any of these issues, be sure to have them repaired.

4. If carrying a heavy load that is slowing you down, you should:

Explanation
The right lanes of a roadway are generally intended for vehicles traveling more slowly than surrounding traffic. If being slowed down by a heavy load, you should stay in the right lane.

5. Older trailers are not equipped with spring brakes. This means that if the air supply for a vehicle's air braking system leaks away:

Explanation
Older trailers do not have spring brakes. This means that if the air supply in an older trailer's air tank has leaked away, there will be no working brakes connected to the trailer and its wheels will turn freely.

6. What is a tire load?

Explanation
Tire load is defined as the maximum safe weight that a tire can carry at a specified pressure.

7. Mirror adjustment can only be checked properly if:

Explanation
On a vehicle with one or more trailers, mirror adjustment can only be checked accurately if the trailers are straight. Mirror adjustment should be checked before the start of every trip.
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