CDL COMBINATION PRACTICE TEST (AZ)
11.
When you make a quick lane change, the crack-the-whip effect can:
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improve your traction.
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make it harder to turn without skidding.
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turn the trailer over.
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12.
When the trailer breaks away or develops a bad leak, the tractor protection valve will close automatically and:
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the trailer emergency brakes will come on.
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the tractor will lose all air pressure.
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the trailer supply valve will stay open.
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13.
If your vehicle is equipped with air brakes, loss of air pressure in the
emergency line causes:
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the trailer spring brakes to come on.
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the speed of your vehicle to increase.
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the trailer emergency brakes to come on.
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14.
The tractor protection valve:
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controls the emergency brakes on combination vehicles.
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keeps air in the tractor brake system should the trailer break away or develop a bad leak.
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supplies air to the trailer air tanks.
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15.
ABS:
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should only be used on dry roads.
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allows you to brake harder.
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is an addition to your normal brakes.
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16.
When backing a tractor under a trailer:
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the end of the kingpin will be even with the top of the fifth wheel.
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the trailer will be lifted slightly when the tractor backs under it.
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the fifth-wheel will come out from under the trailer.
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17.
An Anti-lock Braking System:
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increases a vehicle's stopping power.
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keeps your wheels from locking when you brake hard.
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increases the distamce required to stop on slippery surfaces.
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18.
When you back under a trailer:
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use lowest reverse gear.
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back the tractor slowly.
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All of the above.
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19.
When driving a 50 foot combination vehicle at 50 mph in ideal conditions, you should keep at least ____ seconds of space in front of you.
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5
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10
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6
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20.
Overloading a vehicle with cargo can have negative effects on all of the following except:
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Weight limits
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Steering
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Braking
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