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 two, three or four possible answer choices. Test questions come from the Nebraska 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

8. While inspecting coupling equipment before a trip, the air lines should not:

Explanation
When inspecting the convertor dolly, ensure that all components are present and in proper working condition. Be sure to check the upper and lower fifth wheel, the air lines, and the electric lines. 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 easy turning.

9. What is a concern immediately after it begins raining?

Explanation
Under wet conditions, roads are often most slippery when it first begins to rain. This is because the water mixes with oil and grease on the road that has not yet begun to wash away.

10. Talking on a hands-free phone while driving:

Explanation
While speaking on a hands-free phone while driving is less dangerous than speaking on a hand-held phone, it is just as likely to mentally distract a driver. Simply engaging in conversation takes their mental focus away from the task of driving.

11. If you don't pull a dolly out from beneath the rear trailer before unlocking the pintle hook:

Explanation
Never unlock the pintle hook with the dolly still under the rear trailer. This could cause the dolly tow bar to fly up, possibly causing serious injury.

12. Front brake limiting valves were intended to:

Explanation
Some older vehicles with air brakes have front brake limiting valves. These valves were intended to reduce the risk of front wheels skidding. However, research has shown that such devices are unnecessary, so they should be left in the "normal" position.

13. Which of the following types of vehicles is most prone to the “crack-the-whip" effect?

Explanation
Double and triple combinations are the most vulnerable to turning over as a result of the "crack-the-whip" effect.

14. To ensure normal stopping power, drivers of vehicles equipped with a front brake limiting valve should:

Explanation
Some pre-1975 vehicles have a front brake limiting valve, which has "normal" and "slippery" settings. The idea behind these valves was to limit the air pressure available to the front brakes when driving on slippery surfaces, and thereby reduce the danger of a front-wheel skid. Studies have found that this is not actually a concern, so if your vehicle has a front brake limiting valve, leave it in the "normal" position.
DMV Writen Test Logo