CDL COMBINATION VEHICLE EXAMS SCRIPT QUESTIONS
AND SOLUTIONS RATED A+
✔✔In normal driving, some drivers use the trolley (hand) valve before the brake pedal in
order to prevent trailer skids. When should that be done? - ✔✔It should never be done
✔✔When backing up under a trailer, you should line up - ✔✔Directly in front of the
trailer
✔✔You're hooking up a tractor and semi-trailer, and you've connected both air lines.
Before backing under the trailer you should - ✔✔Supply air to the trailer system, then
pull out the air supply knob to lock the trailer brakes
✔✔When hooking up a tractor to a trailer, you'll know the trailer is at the right height
when the - ✔✔Coupling surface of the trailer is just below the middle of the tractor fifth
wheel
✔✔When not pulling a trailer, why is it a good idea to lock the glad hands together or to
a dummy coupler? - ✔✔It keeps dirt and water out of the lines
✔✔How much space should be between the upper and the lower fifth wheel plates? -
✔✔None
✔✔After Hooking up, you should check the fifth wheel connection by - ✔✔Pulling the
tractor ahead gently with the trailer brakes locked
✔✔When should you use the hand valve to park a combination vehicle? - ✔✔Never
✔✔You have coupled with a semi-trailer. Where should you put the front trailer supports
before driving away? - ✔✔Fully raised with the crank handle secured in its bracket
✔✔You supply air to the trailer tanks by - ✔✔Pushing the trailer air supply valve
✔✔You are coupling a tractor to a semi-trailer and have backed up but are not under it.
What should you hook up before backing under? - ✔✔The emergency and service air
lines
✔✔If the service air 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
✔✔In normal driving, some drivers use the hand valve before a brake pedal to prevent a
jackknife, When should that be done? - ✔✔It should not be done
, ✔✔The air leakage rate for a combination vehicle (engine off, brakes off) should be less
than ____ psi per minute - ✔✔3
✔✔The fifth wheel locking lever is locked after the jaws close around the kingpin. This
means that - ✔✔The coupling is not right and should be fixed before driving the coupled
unit
✔✔Air lines on a combination vehicle are often colored to keep from getting them mixed
up. The emergency line is ______; the service line is ______. - ✔✔Red, Blue
✔✔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
✔✔How much space should be between the upper and lower fifth wheel after coupling?
- ✔✔None
✔✔After you lock the kingpin into the fifth wheel, you should check the connection by -
✔✔Pulling the tractor ahead gently with the trailer brakes locked.
✔✔The safety catch for the fifth wheel locking lever must be - ✔✔Over the locking lever
✔✔After you supply air to the trailer, make sure the air lines are not crossed and the
trailer brakes are working. This is done by - ✔✔Applying and releasing the trailer brakes
and listening for brake sounds
✔✔After connecting the air lines but before braking the under the trailer, you should -
✔✔Supply air to the trailer systems, then pull out the air knob.
✔✔You should not back a tractor under a trailer until the whole air system is - ✔✔At
normal pressure
✔✔Before you back under a trailer, make sure the - ✔✔Trailer brakes are locked
✔✔How should you test the tractor semi-trailer connection for security? - ✔✔Pull gently
forward in low gear against the locked trailer brakes then look at it carefulyl
✔✔You are coupling a semi-trailer to your tractor but we have not yet backed under.
The trailer is at the right height when - ✔✔It will be raised slightly when the tractor is
backed under it
✔✔Here are two things that a driver can do to prevent a rollover. They are:
AND SOLUTIONS RATED A+
✔✔In normal driving, some drivers use the trolley (hand) valve before the brake pedal in
order to prevent trailer skids. When should that be done? - ✔✔It should never be done
✔✔When backing up under a trailer, you should line up - ✔✔Directly in front of the
trailer
✔✔You're hooking up a tractor and semi-trailer, and you've connected both air lines.
Before backing under the trailer you should - ✔✔Supply air to the trailer system, then
pull out the air supply knob to lock the trailer brakes
✔✔When hooking up a tractor to a trailer, you'll know the trailer is at the right height
when the - ✔✔Coupling surface of the trailer is just below the middle of the tractor fifth
wheel
✔✔When not pulling a trailer, why is it a good idea to lock the glad hands together or to
a dummy coupler? - ✔✔It keeps dirt and water out of the lines
✔✔How much space should be between the upper and the lower fifth wheel plates? -
✔✔None
✔✔After Hooking up, you should check the fifth wheel connection by - ✔✔Pulling the
tractor ahead gently with the trailer brakes locked
✔✔When should you use the hand valve to park a combination vehicle? - ✔✔Never
✔✔You have coupled with a semi-trailer. Where should you put the front trailer supports
before driving away? - ✔✔Fully raised with the crank handle secured in its bracket
✔✔You supply air to the trailer tanks by - ✔✔Pushing the trailer air supply valve
✔✔You are coupling a tractor to a semi-trailer and have backed up but are not under it.
What should you hook up before backing under? - ✔✔The emergency and service air
lines
✔✔If the service air 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
✔✔In normal driving, some drivers use the hand valve before a brake pedal to prevent a
jackknife, When should that be done? - ✔✔It should not be done
, ✔✔The air leakage rate for a combination vehicle (engine off, brakes off) should be less
than ____ psi per minute - ✔✔3
✔✔The fifth wheel locking lever is locked after the jaws close around the kingpin. This
means that - ✔✔The coupling is not right and should be fixed before driving the coupled
unit
✔✔Air lines on a combination vehicle are often colored to keep from getting them mixed
up. The emergency line is ______; the service line is ______. - ✔✔Red, Blue
✔✔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
✔✔How much space should be between the upper and lower fifth wheel after coupling?
- ✔✔None
✔✔After you lock the kingpin into the fifth wheel, you should check the connection by -
✔✔Pulling the tractor ahead gently with the trailer brakes locked.
✔✔The safety catch for the fifth wheel locking lever must be - ✔✔Over the locking lever
✔✔After you supply air to the trailer, make sure the air lines are not crossed and the
trailer brakes are working. This is done by - ✔✔Applying and releasing the trailer brakes
and listening for brake sounds
✔✔After connecting the air lines but before braking the under the trailer, you should -
✔✔Supply air to the trailer systems, then pull out the air knob.
✔✔You should not back a tractor under a trailer until the whole air system is - ✔✔At
normal pressure
✔✔Before you back under a trailer, make sure the - ✔✔Trailer brakes are locked
✔✔How should you test the tractor semi-trailer connection for security? - ✔✔Pull gently
forward in low gear against the locked trailer brakes then look at it carefulyl
✔✔You are coupling a semi-trailer to your tractor but we have not yet backed under.
The trailer is at the right height when - ✔✔It will be raised slightly when the tractor is
backed under it
✔✔Here are two things that a driver can do to prevent a rollover. They are:
