CDL - COMBINATION VEHICLE PRACTICE TEST WITH APPROVED
CORRECT ANSWERS | LATEST 2024/2025 A+ GRADE!!.
CDL - COMBINATION VEHICLE
How should you test the tractor semi trailer combination for being properly coupled?
- - ANS - -Pull gently forward in low gear against the locked trailer brakes, then
inspect your coupling.
When coupling to the trailer, how far do you back up before stopping the first time? - -
ANS - -Until the fifth wheel plate just touches the trailer.
What do you check before backing under the trailer? - - ANS - -Make sure the trailer
brakes are set.
Air lines on a combination vehicle are often colored to keep them from getting mixed
up. What color is the emergency line and what color is the service line? - - ANS - -
Red and blue.
After you back up to the trailer and the fifth wheel plate touches the trailer, you set
the tractor park brake, get out and hook up the emergency and service air lines. Then
what do you do before backing under the trailer? - - ANS - -Supply air to the trailer
system, then pull out the trailer air supply knob to fully set the trailer brakes.
What three things can you do to prevent rollovers? - - ANS - -Keep your load
centered, keep the load as low in the trailer as possible, and go slow around turns.
, How far do you raise the landing gear on your trailer? - - ANS - -Crank it up as far as
it will go.
You have coupled with a semi trailer. In what position should you put the landing gear
before driving away? - - ANS - -Fully raised with the crank handle secured in its
bracket.
When uncoupling, what could happen if you park the trailer at an angle? - - ANS - -
You could do damage to the landing gear and dolly legs.
Why should you lock the tractor glad hands together or couple them to the dummy
glad hands when bobtailing? - - ANS - -It will keep dirt and water out of the lines.
When backing under a trailer, you should expect the trailer to be lifted slightly by the
fifth wheel plate. - - ANS - -True.
Before you begin coupling, you should check your travel path for obstacles and
hazards. - - ANS - -True.
What should your air supply pressure gauge read before backing under a trailer? - -
ANS - -100 - 125 psi.
In case of a jackknife situation, you can use your trailer hand valve to apply trailer
brakes to stop the trailer from skidding. - - ANS - -False.
CORRECT ANSWERS | LATEST 2024/2025 A+ GRADE!!.
CDL - COMBINATION VEHICLE
How should you test the tractor semi trailer combination for being properly coupled?
- - ANS - -Pull gently forward in low gear against the locked trailer brakes, then
inspect your coupling.
When coupling to the trailer, how far do you back up before stopping the first time? - -
ANS - -Until the fifth wheel plate just touches the trailer.
What do you check before backing under the trailer? - - ANS - -Make sure the trailer
brakes are set.
Air lines on a combination vehicle are often colored to keep them from getting mixed
up. What color is the emergency line and what color is the service line? - - ANS - -
Red and blue.
After you back up to the trailer and the fifth wheel plate touches the trailer, you set
the tractor park brake, get out and hook up the emergency and service air lines. Then
what do you do before backing under the trailer? - - ANS - -Supply air to the trailer
system, then pull out the trailer air supply knob to fully set the trailer brakes.
What three things can you do to prevent rollovers? - - ANS - -Keep your load
centered, keep the load as low in the trailer as possible, and go slow around turns.
, How far do you raise the landing gear on your trailer? - - ANS - -Crank it up as far as
it will go.
You have coupled with a semi trailer. In what position should you put the landing gear
before driving away? - - ANS - -Fully raised with the crank handle secured in its
bracket.
When uncoupling, what could happen if you park the trailer at an angle? - - ANS - -
You could do damage to the landing gear and dolly legs.
Why should you lock the tractor glad hands together or couple them to the dummy
glad hands when bobtailing? - - ANS - -It will keep dirt and water out of the lines.
When backing under a trailer, you should expect the trailer to be lifted slightly by the
fifth wheel plate. - - ANS - -True.
Before you begin coupling, you should check your travel path for obstacles and
hazards. - - ANS - -True.
What should your air supply pressure gauge read before backing under a trailer? - -
ANS - -100 - 125 psi.
In case of a jackknife situation, you can use your trailer hand valve to apply trailer
brakes to stop the trailer from skidding. - - ANS - -False.
