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MVA CDL Combination Vehicles Study
Guide Questions With Verified Answers
What two things are important to prevent rollover? - answer✔Keep cargo as close to the ground
as possible; Drive slowly around turns.
When you turn suddenly while pulling doubles, which trailer is most likely to turn over? -
answer✔The rear trailer is twice as likely to turn over.
Why should you not use the trailer hand brake to straighten out a jackknifing trailer? -
answer✔Because the brakes on the trailer wheels caused the skid in the first place.
What is off-tracking? - answer✔When a vehicle goes around a corner and the rear wheels follow
a different path than the front wheels.
When you back a trailer, you should position your vehicle so you can back in a curved path
____________________. - answer✔To the drivers side so you can see
What type of trailers can get stuck on railroad-highway crossings? - answer✔Low slung units
(lowboy, car carrier, moving van, possum-belly livestock trailer); Single-axle tractor pulling a
long trailer with its landing gear set to accommodate a tandem-axle tractor.
Why should you not use the trailer hand valve while driving? - answer✔Because of the danger of
making the trailer skid.
Describe what the trailer air supply control does. - answer✔You push it in to supply the trailer
brakes with air, and pull it out to shut off the air supply to put the trailer emergency brakes on.
Describe what the service line is for. - answer✔(Also called the control line or signal line)
Carries air, which is controlled by the foot brake or trailer hand brake. Depending on how hard
you press the foot brake or hand valve, the pressure in the service line will similarly change.
What is the emergency air-line for? - answer✔It supplies air to the trailer air tanks; controls the
emergency brakes on combination vehicles.
Why should you use chocks when parking a trailer without spring brakes? - answer✔The brakes
only hold as long as there is air in the air tank, eventually the air will leak away and there will be
no brakes.
MVA CDL Combination Vehicles Study
Guide Questions With Verified Answers
What two things are important to prevent rollover? - answer✔Keep cargo as close to the ground
as possible; Drive slowly around turns.
When you turn suddenly while pulling doubles, which trailer is most likely to turn over? -
answer✔The rear trailer is twice as likely to turn over.
Why should you not use the trailer hand brake to straighten out a jackknifing trailer? -
answer✔Because the brakes on the trailer wheels caused the skid in the first place.
What is off-tracking? - answer✔When a vehicle goes around a corner and the rear wheels follow
a different path than the front wheels.
When you back a trailer, you should position your vehicle so you can back in a curved path
____________________. - answer✔To the drivers side so you can see
What type of trailers can get stuck on railroad-highway crossings? - answer✔Low slung units
(lowboy, car carrier, moving van, possum-belly livestock trailer); Single-axle tractor pulling a
long trailer with its landing gear set to accommodate a tandem-axle tractor.
Why should you not use the trailer hand valve while driving? - answer✔Because of the danger of
making the trailer skid.
Describe what the trailer air supply control does. - answer✔You push it in to supply the trailer
brakes with air, and pull it out to shut off the air supply to put the trailer emergency brakes on.
Describe what the service line is for. - answer✔(Also called the control line or signal line)
Carries air, which is controlled by the foot brake or trailer hand brake. Depending on how hard
you press the foot brake or hand valve, the pressure in the service line will similarly change.
What is the emergency air-line for? - answer✔It supplies air to the trailer air tanks; controls the
emergency brakes on combination vehicles.
Why should you use chocks when parking a trailer without spring brakes? - answer✔The brakes
only hold as long as there is air in the air tank, eventually the air will leak away and there will be
no brakes.
