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 Oregon Commercial Driver 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 need to correctly answer a minimum of 16 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.
Number of Question
Passing Score
1. An air supply control lever should be in its "normal" position when you are:
Explanation
Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "normal" position, it is properly set for you to pull a trailer.
2. 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.
3. In a double or triple combination:
Explanation
When positioning trailers in a combination, the most heavily-loaded trailer should be the closest to the tractor. The lightest trailer should be positioned in the rear.
4. To prevent a rollover, cargo should be:
Explanation
To reduce the risk of rollover, the weight of cargo in a trailer should be centered and spread out as much as possible. The weight of the cargo should also be kept as low to the ground as possible.
5. 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.
6. Watching the road ahead:
Explanation
Making a sudden lane change can be dangerous while driving a combination vehicle. You can avoid the need to make a sudden lange change by looking down the road for upcoming obstacles that will require you to change lanes.
7. What is a bobtail tractor?
Explanation
