CDL COMBINATION VEHICLE FINAL EXAM ACTUAL
QUESTIONS AND SOLUTIONS RATED A+
✔✔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:
Go slow around turns and - ✔✔Keep the cargo as close to the ground as possible
✔✔Which part of the kingpin should the locking jaws close around? - ✔✔The shank
✔✔True or False?
"Bobtail" trailers can take longer to stop than a combination vehicle loaded to maximum
gross weight - ✔✔True
✔✔Your emergency air line breaks or gets pulled apart while you are driving. The loss
of pressure will cause the - ✔✔Emergency trailer brakes to come one
✔✔Why should you be sure that the fifth wheel plate is greased as required? - ✔✔To
prevent steering problems
✔✔What will happen if the air lines are crossed when you hook up to an old trailer? -
✔✔If the trailer has no spring brakes, you could drive away but you would not have
trailer brakes
✔✔The front trailer supports are up and the trailer is resting on the tractor. What two
things should you make sure of? - ✔✔There is enough clearance between the tops of
the tractor tires and the nose of the trailer
There is enough clearance between the tractor frame and the landing gear
, ✔✔You have a major leak in the service line and you put on the brakes. Service air
pressure will escape and cause the - ✔✔Trailer emergency brakes to come on
✔✔Why should you lock the tractor glad hands to each other (or dummy couplers) when
you are not towing a trailer? - ✔✔It will keep dirt and water out of the lines
✔✔The hand valve should be used - ✔✔To test the trailer brakes
✔✔Semi-trailers made before 1975 that are equipped with air brakes - ✔✔Often do not
have spring brakes
✔✔When you get ready to back under a semi-trailer, you should line up - ✔✔Directly in
front of the trailer
✔✔The air leakage rate for a combination vehicle (engine off, brakes on) should be less
than _____ psi per minute - ✔✔4
✔✔You can prevent a roll over by keeping the cargo as close to the ground as possible
and - ✔✔Going slow around curves
✔✔Why are "Bobtail" tractors harder to stop? - ✔✔The vehicle is lighter
✔✔ Air lines on a combination vehicle are often colored to keep from getting them
mixed up. The emergency line is - ✔✔Red
✔✔There are two things that a driver can do to prevent a rollover. They are:
Keep the cargo as close to the ground as possible, and - ✔✔Reduce speed before
entering turns
✔✔If the service line disconnects while you're driving, what will happen right away? -
✔✔Nothing is likely to happen until you try the brakes
✔✔How do you supply air to the air tank on the trailer? - ✔✔By pushing in the trailer air
supply valve
✔✔With the engine off and the brakes released, a combination vehicle air brake system
shouldn't leak more than how many psi in one minute? - ✔✔3 psi
✔✔You're hooking a tractor to a semi-trailer and have backed up but are not under it.
What should you do before backing under the trailer? - ✔✔Hook up the emergency and
service air lines
QUESTIONS AND SOLUTIONS RATED A+
✔✔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:
Go slow around turns and - ✔✔Keep the cargo as close to the ground as possible
✔✔Which part of the kingpin should the locking jaws close around? - ✔✔The shank
✔✔True or False?
"Bobtail" trailers can take longer to stop than a combination vehicle loaded to maximum
gross weight - ✔✔True
✔✔Your emergency air line breaks or gets pulled apart while you are driving. The loss
of pressure will cause the - ✔✔Emergency trailer brakes to come one
✔✔Why should you be sure that the fifth wheel plate is greased as required? - ✔✔To
prevent steering problems
✔✔What will happen if the air lines are crossed when you hook up to an old trailer? -
✔✔If the trailer has no spring brakes, you could drive away but you would not have
trailer brakes
✔✔The front trailer supports are up and the trailer is resting on the tractor. What two
things should you make sure of? - ✔✔There is enough clearance between the tops of
the tractor tires and the nose of the trailer
There is enough clearance between the tractor frame and the landing gear
, ✔✔You have a major leak in the service line and you put on the brakes. Service air
pressure will escape and cause the - ✔✔Trailer emergency brakes to come on
✔✔Why should you lock the tractor glad hands to each other (or dummy couplers) when
you are not towing a trailer? - ✔✔It will keep dirt and water out of the lines
✔✔The hand valve should be used - ✔✔To test the trailer brakes
✔✔Semi-trailers made before 1975 that are equipped with air brakes - ✔✔Often do not
have spring brakes
✔✔When you get ready to back under a semi-trailer, you should line up - ✔✔Directly in
front of the trailer
✔✔The air leakage rate for a combination vehicle (engine off, brakes on) should be less
than _____ psi per minute - ✔✔4
✔✔You can prevent a roll over by keeping the cargo as close to the ground as possible
and - ✔✔Going slow around curves
✔✔Why are "Bobtail" tractors harder to stop? - ✔✔The vehicle is lighter
✔✔ Air lines on a combination vehicle are often colored to keep from getting them
mixed up. The emergency line is - ✔✔Red
✔✔There are two things that a driver can do to prevent a rollover. They are:
Keep the cargo as close to the ground as possible, and - ✔✔Reduce speed before
entering turns
✔✔If the service line disconnects while you're driving, what will happen right away? -
✔✔Nothing is likely to happen until you try the brakes
✔✔How do you supply air to the air tank on the trailer? - ✔✔By pushing in the trailer air
supply valve
✔✔With the engine off and the brakes released, a combination vehicle air brake system
shouldn't leak more than how many psi in one minute? - ✔✔3 psi
✔✔You're hooking a tractor to a semi-trailer and have backed up but are not under it.
What should you do before backing under the trailer? - ✔✔Hook up the emergency and
service air lines
