CDL COMBINATION VEHICLE EXAM, PRACTICE EXAM AND STUDY GUIDE NEWEST 2024 ACTUAL EXAM 300 QUESTIONS AND CORRECT DETAILED ANSWERS WITH (VERIFIED ANSWERS) |ALREADY GRADED A+

CDL COMBINATION VEHICLE EXAM, PRACTICE
EXAM AND STUDY GUIDE NEWEST 2024 ACTUAL
EXAM 300 QUESTIONS AND CORRECT DETAILED
ANSWERS WITH (VERIFIED ANSWERS) |ALREADY
GRADED A+
Why should you lock the tractor glad hands (or
dummy couplers) to each other when you are not
towing a trailer?
A. The connected brake circuit becomes a backup air
tank.
B. If you did not, you could never build system
pressure.
C. It will keep dirt and water out of the lines. -
...ANSWER...It will keep dirt and water out of the lines.
For coupling to be completed, the safety catch for the
fifth wheel locking lever must be:
A. Straight up.
B. Over the locking lever.
C. Through the locking lever. - ...ANSWER...Over the
locking lever.
The front trailer supports are up and trailer is resting
on the tractor. Make sure:
A. There is enough clearance between the upper and
lower fifth wheel.
B. The safety latch is in the unlocked position.
C. There is enough clearance between the tractor
frame and the landing gear. - ...ANSWER...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:
A. Trailer tank pressure to be lost.
B. Trailer emergency brakes to come on.
C. Tractor spring brakes to lock on. -
...ANSWER...Trailer emergency brakes to come on.
When backing under a tractor under a trailer you
should expect:
A. Trailer will be lifted slightly when the tractor backs
under it.
B. End of the kingpin is even with the top of the fifth
wheel. C. Trailer landing gear is fully extended. -
...ANSWER...Trailer will be lifted slightly when the
tractor backs under it.
The driver crosses the air lines when hooking up to an
old trailer. What will happen?
A. If the trailer has no spring brakes, you can drive
away, but you will not have trailer brakes.
B. The brake pedal will work the trailer spring brakes
instead of the air brakes.
C. The hand valve will apply the tractor brakes instead
of the trailer brakes. - ...ANSWER...If the trailer has no
spring brakes, you can drive away, but you will not
have trailer brakes.
You are coupling a tractor to a semi-trailer and have
backed up but are not under it. What should you hook
up before backing under the semi-trailer?
A. The emergency and service air lines.
B. The electrical service cable.
C. Nothing, back up and lock the fifth wheel. -
...ANSWER...The emergency and service air lines.
Air lines on a combination vehicle are often colored to
keep them from getting mixed up. The emergency line
is ____; the service line is ____.
A. Red, blue
B. Blue, red
C. Black, yellow - ...ANSWER...Red, blue
Which of these statements is true?
A. Light vehicles need more braking power to stop
than heavy ones.
B. Always delay braking a heavy vehicle until you have
no other choice.
C. "Bobtail" tractors can take longer to stop than a
combination vehicle loaded to the maximum gross
weight. - ...ANSWER..."Bobtail" tractors can take
longer to stop than a combination vehicle loaded to
the maximum gross weight.
After connecting the air lines, but before backing
under the trailer, you should:
A. Make sure that the trailer brakes are off.
B. Supply air to the trailer system, then pull out the air
supply knob.
C. Walk around the rig to make sure it is clear. -
...ANSWER...Supply air to the trailer system, then pull
out the air supply knob.