NC CDL COMBINATION VEHICLES ACTUAL PRACTICE TEST STUDY GUIDE – WELL
SOLVED Q&A GRADED A+
Which of these statements is true?
"Bobtail" tractors can take longer to stop than a combination vehicle loaded to the
maximum gross weight.
After connecting the air lines, but before backing under the trailer, you should:
Supply air to the trailer system, then pull out the air supply knob.
The hand valve should be used:
To test the trailer brakes.
The air leakage rate for a combination vehicle (engine off, brakes off) should be no more
than ___ PSI per minute.
3
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This
means that:
The coupling is not right and should be fixed before driving the vehicle.
,You are driving a combination vehicle when the trailer breaks away, pulling apart both air
lines. You would expect the trailer brakes to come on and:
The tractor protection valve to close.
Semi-trailers made before 1975 that are equipped with air brakes:
Often do not have spring brakes.
Almost half of all truck driver deaths are the result of:
Rollovers.
What statement best explains "crack the whip effect"?
When you make a quick lane change or sudden movement with your steering wheel, the
rear trailer tends to swing out. The force of the rear trailer becomes amplified, causing it to
roll over (rearward amplification).
Which type of truck-trailer combination has the best chance of the "crack the whip"
rollover?
A tractor pulling 3 trailers.
Which trailers are most likely to get stuck on railroad tracks?
Lowboy trailers. A low slung unit. Possum-belly livestock trailers. A low slung unit. Single
axle tractors pulling a short trailer. A low slung unit.
, Where should the tractor be when you inspect landing gear after uncoupling the trailer?
With the tractor frame under the trailer.
Under good driving conditions, you should leave at least one second of space between
your vehicle and the vehicle ahead for every ____ feet of your vehicle's length.
10
The safest way to make a turn without entering another traffic lane is:
You should turn wide as you complete the turn.
In general, the higher your truck's center of gravity, the:
Easier it is to turn over.
If the service line comes apart while you are driving a combination vehicle, but the
emergency line stays together, what will happen right away?
Nothing is likely to happen until you try to apply the brakes.
Glad hands are used to connect the:
Service and emergency air lines from the truck to the trailer.
SOLVED Q&A GRADED A+
Which of these statements is true?
"Bobtail" tractors can take longer to stop than a combination vehicle loaded to the
maximum gross weight.
After connecting the air lines, but before backing under the trailer, you should:
Supply air to the trailer system, then pull out the air supply knob.
The hand valve should be used:
To test the trailer brakes.
The air leakage rate for a combination vehicle (engine off, brakes off) should be no more
than ___ PSI per minute.
3
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This
means that:
The coupling is not right and should be fixed before driving the vehicle.
,You are driving a combination vehicle when the trailer breaks away, pulling apart both air
lines. You would expect the trailer brakes to come on and:
The tractor protection valve to close.
Semi-trailers made before 1975 that are equipped with air brakes:
Often do not have spring brakes.
Almost half of all truck driver deaths are the result of:
Rollovers.
What statement best explains "crack the whip effect"?
When you make a quick lane change or sudden movement with your steering wheel, the
rear trailer tends to swing out. The force of the rear trailer becomes amplified, causing it to
roll over (rearward amplification).
Which type of truck-trailer combination has the best chance of the "crack the whip"
rollover?
A tractor pulling 3 trailers.
Which trailers are most likely to get stuck on railroad tracks?
Lowboy trailers. A low slung unit. Possum-belly livestock trailers. A low slung unit. Single
axle tractors pulling a short trailer. A low slung unit.
, Where should the tractor be when you inspect landing gear after uncoupling the trailer?
With the tractor frame under the trailer.
Under good driving conditions, you should leave at least one second of space between
your vehicle and the vehicle ahead for every ____ feet of your vehicle's length.
10
The safest way to make a turn without entering another traffic lane is:
You should turn wide as you complete the turn.
In general, the higher your truck's center of gravity, the:
Easier it is to turn over.
If the service line comes apart while you are driving a combination vehicle, but the
emergency line stays together, what will happen right away?
Nothing is likely to happen until you try to apply the brakes.
Glad hands are used to connect the:
Service and emergency air lines from the truck to the trailer.
