CDL COMBINATION VEHICLE ACTUAL TEST QUESTIONS
AND SOLUTIONS RATED A+
✔✔Compared with a straight truck or bus, there are ________ things to inspect in
combination vehicles.
1. fewer
2. more
3. the same number of - ✔✔more
✔✔What is the emergency air line for?
1. To engage the trailer brakes in case of air pressure loss
2. To have extra air pressure in case you need it
3. To engage the front brakes of the tractor in case of an emergency - ✔✔To engage
the trailer brakes in case of air pressure loss
✔✔The tractor protection valve will close and the trailer _______ brakes will come on
when there is a major leak in the brake line.
1. parking
2. service
3. emergency - ✔✔emergency
✔✔A trailer is most likely to jackknife when it is ...
1. loaded to full capacity
2. overloaded
3. empty - ✔✔empty
✔✔When you are uncoupling a loaded trailer, lower the landing gear until it ...
1. reaches the ground
2. makes firm contact with the ground
3. makes contact with the ground, and leave the trailer off the fifth wheel - ✔✔makes
firm contact with the ground
✔✔How much space should there be between the upper and lower fifth wheel after
coupling?
1. Just enough to see light through it
2. About 1/4 inch
3. None - ✔✔none
✔✔After you have coupled the trailer, you should start to raise the landing gear by using
1. low gear
2. high gear
3. intermediate gear - ✔✔low gear
, ✔✔The fifth wheel locking lever is not locked after the jaws close around the kingpin.
This means that
1. the parking lock is off and you may drive away
2. the coupling is not right and should be fixed before you drive the coupled unit
3. the trailer will not swivel on the fifth wheel - ✔✔the coupling is not right and should be
fixed before you drive the coupled unit
✔✔When checking the trailer emergency brakes, make sure that the tractor protection
control valve is placed in the _______ position.
1. normal
2. emergency
3. neutral - ✔✔emergency
✔✔You should use chocks when parking a trailer without spring brakes because
1. if the air supply leaks away, there will be no brakes
2. some states require chocking of trailer wheels
3. you dont want the trailer rolling down a hill - ✔✔if the air supply leaks away, there will
be no brakes
✔✔You are uncoupling a trailer. After you shut off the trailer air supply and lock the
trailer brakes, you should
1. begin to lower the trailer landing gear
2. immediately apply your tractor parking brakes
3. back up gently to ease pressure on the fifth wheel locking jaw - ✔✔back up gently to
ease pressure on the fifth wheel locking jaw
✔✔While you are driving, your emergency air line breaks or gets pulled apart. The loss
of pressure will cause the
1. air compressor to unload instead of pumping air
2. trailer emergency brakes to come on
3. trailer supply valve to open - ✔✔trailer emergency brakes to come on
✔✔You are coupling a tractor to a semi-trailer. You have backed up but are not yet
under it. Before backing under the semi trailer, you should hook up
1. the electrical service cable
2. nothing. Back up and lock the fifth wheel
3. The emergency and service air lines - ✔✔the emergency and service air lines
✔✔When backing a tractor under a trailer, you should expect that
1. the trailer will be lifter slightly when the tractor backs under it
2. the trailer landing gear is fully extended
3. the end of the kingpin is even with the top of the fifth wheel - ✔✔the trailer will be
lifting slightly when the tractor backs under it
AND SOLUTIONS RATED A+
✔✔Compared with a straight truck or bus, there are ________ things to inspect in
combination vehicles.
1. fewer
2. more
3. the same number of - ✔✔more
✔✔What is the emergency air line for?
1. To engage the trailer brakes in case of air pressure loss
2. To have extra air pressure in case you need it
3. To engage the front brakes of the tractor in case of an emergency - ✔✔To engage
the trailer brakes in case of air pressure loss
✔✔The tractor protection valve will close and the trailer _______ brakes will come on
when there is a major leak in the brake line.
1. parking
2. service
3. emergency - ✔✔emergency
✔✔A trailer is most likely to jackknife when it is ...
1. loaded to full capacity
2. overloaded
3. empty - ✔✔empty
✔✔When you are uncoupling a loaded trailer, lower the landing gear until it ...
1. reaches the ground
2. makes firm contact with the ground
3. makes contact with the ground, and leave the trailer off the fifth wheel - ✔✔makes
firm contact with the ground
✔✔How much space should there be between the upper and lower fifth wheel after
coupling?
1. Just enough to see light through it
2. About 1/4 inch
3. None - ✔✔none
✔✔After you have coupled the trailer, you should start to raise the landing gear by using
1. low gear
2. high gear
3. intermediate gear - ✔✔low gear
, ✔✔The fifth wheel locking lever is not locked after the jaws close around the kingpin.
This means that
1. the parking lock is off and you may drive away
2. the coupling is not right and should be fixed before you drive the coupled unit
3. the trailer will not swivel on the fifth wheel - ✔✔the coupling is not right and should be
fixed before you drive the coupled unit
✔✔When checking the trailer emergency brakes, make sure that the tractor protection
control valve is placed in the _______ position.
1. normal
2. emergency
3. neutral - ✔✔emergency
✔✔You should use chocks when parking a trailer without spring brakes because
1. if the air supply leaks away, there will be no brakes
2. some states require chocking of trailer wheels
3. you dont want the trailer rolling down a hill - ✔✔if the air supply leaks away, there will
be no brakes
✔✔You are uncoupling a trailer. After you shut off the trailer air supply and lock the
trailer brakes, you should
1. begin to lower the trailer landing gear
2. immediately apply your tractor parking brakes
3. back up gently to ease pressure on the fifth wheel locking jaw - ✔✔back up gently to
ease pressure on the fifth wheel locking jaw
✔✔While you are driving, your emergency air line breaks or gets pulled apart. The loss
of pressure will cause the
1. air compressor to unload instead of pumping air
2. trailer emergency brakes to come on
3. trailer supply valve to open - ✔✔trailer emergency brakes to come on
✔✔You are coupling a tractor to a semi-trailer. You have backed up but are not yet
under it. Before backing under the semi trailer, you should hook up
1. the electrical service cable
2. nothing. Back up and lock the fifth wheel
3. The emergency and service air lines - ✔✔the emergency and service air lines
✔✔When backing a tractor under a trailer, you should expect that
1. the trailer will be lifter slightly when the tractor backs under it
2. the trailer landing gear is fully extended
3. the end of the kingpin is even with the top of the fifth wheel - ✔✔the trailer will be
lifting slightly when the tractor backs under it
