Instructions

Combination

All applicants who are applying for a Class A CDL should be prepared to take the Combination test. This test covers information found in Section 6 of the Nebraska Commercial Driver License Manual. Section 6 provides the information needed to safely operate tractor-trailers, doubles, triples, and straight trucks with trailers. The test is made up of 25 multiple-choice questions, and applicants will need to correctly answer a minimum of 20 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 25

Passing Score 20

1. Which type of vehicle is most prone to the “crack-the-whip” effect?

A five-axle tractor semi-trailer

A three-axle tractor semi-trailer

A bobtail tractor

A triple trailer

Triple combination trailers are most vulnerable to the "crack-the-whip" effect.

2. Trailers with low underneath clearance can present challenges when driving over:

Bridges.

Railroad tracks.

Overpasses.

Railroad-highway crossings may be difficult to cross when pulling a trailer with a low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

3. When entering or crossing traffic while driving a combination vehicle, it is especially important that you:

Sound your horn.

Make sure there is a large enough gap for your vehicle.

Expect other drivers to make room for your vehicle.

Let other drivers wave you into their lane.

Combination vehicles require more space on the road than other vehicles. When entering or crossing traffic while driving a combination vehicle, it is especially important that there is a large enough gap in traffic for you to safely do so.

4. Place the trailer air supply control in its "emergency" position to test:

The trailer emergency brakes.

A coupling device.

The anti-lock brakes.

Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.

5. The ____ trailer is the most likely to turn over if a driver takes a turn too quickly.

Front

Last

Middle

When making a turn, be sure to steer gently and smoothly. Making a quick turn while pulling trailers is dangerous and can increase the risk of the last trailer rolling over.