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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.
An item that is 15 feet long placed on a flatbed trailer should have at least:
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2 tie-downs.
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3 tie-downs.
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1 tie-down.
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2.
Having ABS on only the trailer:
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still gives you more control over your vehicle during braking.
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makes the trailer more likely to swing out.
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is very dangerous.
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3.
Air brakes:
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are an effective way to stop large and heavy vehicles.
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should be used only when driving on wet roads.
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are prohibited on larger vehicles.
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4.
In combination vehicles with air brakes, the trailer air supply control should pop out when the air pressure falls within the range of:
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100 to 120 psi
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10 to 20 psi
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20 to 45 psi
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5.
In combination vehicles with air brakes, the trailer air supply control:
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is used to control the tractor protection valve.
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is a coupling devices used to connect the service and emergency air-lines from the tractor to the trailer.
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is used to keep the trailer behind the tractor.
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6.
Anti-lock brakes:
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increase your stopping distance.
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help you stop faster.
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keep your brakes from locking up when you brake hard.
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7.
When driving on slippery roads, you should NOT:
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use the engine brake.
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go slowly.
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try to anticipate stops early.
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8.
A trailer jackknife is more likely to happen when the trailer is:
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empty.
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overloaded.
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loaded to its full capacity.
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9.
If you will be transporting hazardous materials that require placards, you must:
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transport the materials at night only.
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obtain a hazardous materials endorsement.
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obtain a special transit permit.
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10.
Overloading can have negative effects on:
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steering.
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braking.
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All of the above.
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