WASHINGTON CDL COMBINATION PRACTICE TEST
11.
What is the emergency air line for?
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It supplies air to the trailer air tanks, and controls the emergency brakes on combination vehicles.
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It controls the front brakes of the tractor in case of an emergency.
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It tells you the amount of brake pressure you need to stop the vehicle.
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12.
Which of the following is NOT a good rule for using turn signals?
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Signal continuously until you have completed the turn.
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Cancel your signal after you have turned.
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Put your turn signal on after the turn.
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13.
During a trip:
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you should not watch gauges as they can be misleading.
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you should watch gauges to make sure that valve caps are not missing.
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you should watch gauges for signs of trouble.
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14.
When uncoupling a trailer, after shutting off the trailer air supply to lock the trailer brakes, you should:
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pull the tractor forward until the fifth-wheel comes out from under the trailer.
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back up gently to ease the pressure on the fifth-wheel locking jaws.
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inspect the trailer supports.
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15.
When you drive a tractor-trailer combination with ABS, you should:
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apply the trailer hand brake whe braking.
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brake as you always have.
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pump the brakes.
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16.
When the wheels of a trailer lock up:
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the vehicle will gradually come to a complete stop.
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ABS will increase stopping power.
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the trailer will tend to swing around.
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17.
What is a tractor jackknife?
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When the wheels of a trailer lock up, and the trailer swings around.
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When a drive-wheel skid lets the trailer push the towing vehicle sideways.
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None of the above.
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18.
If you are driving a 30 foot vehicle at 35 mph, you should leave at least _______ between your vehicle and the vehicle in front of you.
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2 seconds
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3 seconds
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4 seconds
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19.
If your cargo only fills one-third of the length of your trailer, make sure your cargo is:
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centered and spread out as much as possible.
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piled up high with heavy cargo on top.
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to one side and as close to the ground as possible.
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20.
When more cargo is piled up in a truck, the center of gravity moves:
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higher up from the road.
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to the left side of the truck.
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closer to the ground.
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