Combination Flashcards
when backing a tractor under a trailer, you should
always use the lowest reverse gear
after the trailer has been coupled to the tractor, the tractor protection control valve should be placed in what position
Normal
the fifth wheel locking lever is not locked after the jaws closed around the kingpin. this means that
the coupling is not right and should be fixed before driving the coupled unit
off tracking or cheating causes which of these to follow the wider pass while making a turn
tractor towing a 45 foot trailer
the air lines on a combination vehicle are often colored to prevent them from being mixed up. the emergency line is BLANK; the service line is BLANK
Red and Blue
the semitrailers made before 1975 that are equipped with air brakes
often do not have spring brakes
the air leakage rate for combination vehicle (Engine off, brakes on) should be less than BLANK psi per minute
4
compared to a straight truck or bus, there are BLANK things to inspect in a combination vehicle
More
you have a major leak in the service line and you put on the brakes, the service air will escape and cause
the trailer emergency brakes to come on
a tractor with a BLANK trailer requires the shortest amount of stopping distance
fully loaded
when you get ready to back under a semitrailer, you should line up
directly infront of the trailer
to unlock the fifth wheel the locking lever should be place in the BLANK position
open
the tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in the BLANK brake line
Emergency
when coupling, the proper position of the fifth wheel is
tilted down towards the end of the trailer
what gear should be the tractor engine be in after you uncouple the trailer and are inspecting the trailer supports?
Neutral
you have coupled with a semi trailer. where should you put the iron trailer supports before driving away
fully raised with the crank handle secured in its bracket
the safetyy catch for the fifth wheel locking lever must be BLANK for the coupling to be complete
over the locking lever
after you supply 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 and listening the sound of the brake
before you back under a trailer, make sure that
the trailer brakes are locked
when you uncoupling a loaded trailer, you should lower the landing gear until it
makes firm contact with the ground, then crackle hit a lower gear a few extra turns
what will happen if the air lines are closed when you hook up to an old trailer?
if the trailer has no spring brakes, you could drive away, but you wouldnt have trailer brakes
there are two things a driver can do to prevent a roll over. (1) keep the cargo as close to the ground as possible, and (2)
go slow around turns
to stop a trailer skid, you should
release the service brakes
why should you be sure that the fifth wheel plate is greased as required?
to prevent steering problems
you emergency air line breaks or get pulled apart while you are driving. the loss of pressure will cause
emergency trailer brakes to come on
when connecting the glad hands, press the two seals with the coupler together at what degree to each other
90 degrees
which of these statements is true?
bobtail tractor can take longer to stop than a combination vehicle loaded to maximum gross weight
a tractor with BLANK trailer, requires the shortes amount of stopping distance
fully loaded
after you have coupled the trailer, you should raise the landing gear by using
low gear
you supply air to the trailer tanks by
pushing in the trailer air supply valve
which part of the kingpin should the locking jaws close around
the shank
how much space should be allowed between upper and lower fifth wheel after coupling
Nothing
you have pushed the trailer air supply valve. you should not back a tractor under a trailer until the whole air system is
at normal pressure
you are coupling a tractor to a semitrailer. you have connected the air lines. before backing under the trailer, you should
supply air to the trailer system, then pull out the air supply knob
the air brake leakage rate for a combination vehicle (engine off, brakes off) should be less than BLANK psi per minute
3
the safest way to make a turn without entering another traffic lane is
you should turn wide as you complete your turn
the higher the center of gravity of your truck, the
easier to turn over
a driver crosses the air lines when hooking up to an old trailer, what will happen?
if the trailer has no spring brakes, you could drive away, but you wouldnt have trailer brakes
the hand valed should be used
to test the trailer brakes
when driving a set of doubles, it is necessary to close which shut off valve in the last trailer
Back
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
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
you are coupling a tractor to a semitrailer and have back up, but are not under it, what should you hook up before backing under?
the emergency and service air lines
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 or water out of the lines
while driving behind another vehicle under good conditions, you should allow at least one second between you vehicle and the vehicle ahead for each BLANK(how many) feet of your vehicle length
10
if the service lines come apart while you are driving a combination vehicle, but the emergency lines stay together, what will happen right away?
nothing is likely to happen until you apply the brakes
glad hands are usually connecting which of these
Service and emergency air lines from the vehicle to the trailer
you are about to back your tractor under a semitrailer. the trailer is at the right height when the
the trailer will be lifted slightly when the tractor backs under it
while checking if the tractor is securely coupled to the trailer, the landing gears should be
slightly raised
air and electrical lines from the tractor to the trailer should be
secured but with enough loop to turn
you should not back a tractor under a trailer until the whole air system is
at normal pressure
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
where should the tractor be when you inspect landing gear after uncoupling the trailer?
with the tractor frame under the trailer
your emergency air line breaks or gets pulled apart while you are driving. the loss of pressure will cause
emergency trailer brakes to come on
the front trailer supports are up and the trailer is resting on the tractor. make sure
there is enought clearance between the top of the tractor tires, the nose of the trailer, tractor frame and landing gear
when uncoupling the trailer, after you shut off the trailer air supply and lock the trailer brakes you should
back up gently to ease pressure on the fifth wheel
air brake equipped trailer made before 1975
often do not have spring brakes
the iron trailer supports are up and the trailer is resting on the tractor. make sure
there is enough clearance between the tractor frame and landing gear
if you cannot make a turn without entering another traffic lane
you should turn wide as you complete turn
when checking the trialer emergency brakes, the trator protection control valve should be placed in what position?
Emergency
you are driving a combination vehicle when the trailer breaks away, pulling apart both the air lines, you expect the trailer brakes to come on
the tractor protection valve to close
in normal driving, some drivers use the hand valves before the brake pedal to prevent a jackknife, which of these statements is true
it should not be done
when should you use the hand valve to park a combination vehicle
never
if the brakes are not released when you push the trailer air supply valves, you should
check the air line connection
