CDL COMBINATION PRACTICE TEST ALABAMA
11.
In combination vehicles with air brakes, the trailer air supply control:
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is used to keep the trailer behind the tractor.
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is used to control the tractor protection valve.
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supplies air to the trailer air tanks.
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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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12.
Most hydraulic brake failures occur for one of two reasons, one of which is:
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relying too much on the engine braking effect.
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loss of hydraulic pressure.
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driving in cold weather.
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excessive downshifting.
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13.
You should not use the trailer hand brake to straighten out a jackknifing trailer. Why?
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You should use the service break instead.
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The brakes on the trailer wheels will not respond.
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You should use the emergency break instead.
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The brakes on the trailer wheels caused the skid in the first place.
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14.
The only way to stop a front-wheel skid is to:
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let the vehicle slow down.
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countersteer.
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supply more power to the drive wheels.
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All of the above.
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15.
An Anti-lock Braking System (ABS):
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increases your normal braking capability.
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keeps your wheels from locking up when you brake hard.
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always shortens your stopping distance.
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lets you drive faster.
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16.
Inspecting the fifth-wheel does NOT include:
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backing until the fifth-wheel just touches the trailer.
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checking that there are no cracks in the frame.
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making sure that the fifth wheel is in the proper position for coupling.
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checking for missing or damaged parts.
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17.
Strong winds can make it difficult to stay in your lane especially when driving:
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flatbed trailers.
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heavier vehicles.
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vehicles with ABS.
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lighter vehicles.
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18.
Tar in the road pavement rising to the road surface in very hot weather:
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causes the road to become very slippery.
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might get in your engine.
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does not affect the road surface or driving conditions.
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is very sticky and will slow down your vehicle.
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19.
Do not use the trailer hand valve in driving because:
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the brakes can overheat and lose their braking power.
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of the danger of making the trailer skid.
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the trailer emergency brakes will come on.
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All of the above.
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20.
When you are driving on a slippery road, you should NOT:
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use the engine brake or speed retarder.
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keep a longer following distance.
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adjust turning and braking to road conditions.
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take curves at slower speeds.
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