# 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 Commercial Driver License..

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 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 20 multiple-choice questions, and applicants will have one hour to correctly answer a minimum of 16 questions. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question
Passing Score

### 1. The trailer hand valve should:

Explanation
The trailer hand valve works the trailer brakes but should only be used when testing them. Using it while driving could create a skid. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place.

### 2. 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.

### 3. Using the trailer hand brake while experiencing a trailer jackknife will:

Explanation
If you are experiencing a trailer jackknife, you can help your tires regain traction by releasing the brakes. Using a trailer hand brake while experiencing a skid will only cause the skid to continue.

### 4. Using the trailer hand valve while driving:

Explanation
Never use the trailer hand valve while operating your vehicle. Using the trailer hand valve while driving can cause your trailer to skid.

### 5. Driving a combination vehicle ____ than driving a single vehicle.

Explanation
Driving a combination vehicle usually requires more skill than driving a single vehicle. Combination vehicles are generally longer and heavier than single commercial vehicles.

### 6. Simply changing lanes can cause:

Explanation
Due to the "crack-the-whip" effect caused by rearward amplification, changing lanes too quickly in a combination vehicle can result in a rollover.

### 7. Avoid needing to make sudden lane changes by:

Explanation
Making a sudden lane change can be dangerous when driving a combination vehicle. Avoid the need to make a sudden lane change by looking down the road for upcoming obstacles that will require you to change lanes.