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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Iowa CDL combination test consists of 20 questions, and you'll need at least 16 correct answers to pass (80%). The test covers the combination vehicles section of the Iowa CDL Manual. Take this practice test now to prepare for the actual IA CDL combination test!
1. What is the proper following distance for a 40 foot truck traveling at 35 mph?
12 seconds
4 seconds
10 seconds
2. You are coupling a tractor to a semi-trailer. After checking the trailer height but before supplying air to the trailer, you should:
lock the trailer brakes.
connect the air lines to the trailer.
inspect the fifth-wheel.
3. Transporting hanging meat requires special attention. Why?
Because hanging meat can be an unstable load with a high center of gravity.
Because you have to drive fast to get it delivered fresh.
Because refrigerated trucks have less traction.
4. If you unlock the pintle hook with the dolly still under the rear trailer:
your vehicle might roll away.
the brakes could be damaged by the combined forces of the springs and the air pressure.
the dolly tow bar may fly up.
5. You must have at least 4/32 inch tread depth in every major groove on front tires and at least ___ inch on other tires.
6. After supplying air to the trailer brake system, you should check the brake system for crossed air lines by:
applying and releasing the trailer brakes and listening for the sound of trailer brakes.
shutting the engine off so you can hear the brakes.
All of the above.
7. Broken suspension parts can be very dangerous. When inspecting your vehicle for suspension system defects, look for:
Spring hangers that allow movement of axle from proper position.
Broken leaves in a multi-leaf spring.
All of the above.
8. Longer combination vehicles have the tendency to swing wide on turns. This is called:
9. Do not use the trailer hand valve in driving because:
of the danger of making the trailer skid.
the trailer emergency brakes will come on.
All of the above.
10. Which of the following is NOT TRUE? When you drive a tractor-trailer combination with ABS, you should:
monitor your tractor and trailer as you slow down, and if it is safe to do so, back off the brakes to stay in control.
brake the same way, regardless of whether you have ABS on the tractor, the trailer, or both.
drive slower to keep your vehicle in a straight line.
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IA Combination Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
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