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
spring has no
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.
The hand valve should be used:
A. To test the trailer brakes.
B. Only when the trailer is fully loaded.
C.Only with the foot brake. - ...ANSWER...To
test the trailer brakes.
The air leakage rate for a combination vehicle
(engine off, brakes off) should be no more
than ___ PSI per minute.
A.
2
B. 4 - ...ANSWER...3
C.
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
spring has no
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.
The hand valve should be used:
A. To test the trailer brakes.
B. Only when the trailer is fully loaded.
C.Only with the foot brake. - ...ANSWER...To
test the trailer brakes.
The air leakage rate for a combination vehicle
(engine off, brakes off) should be no more
than ___ PSI per minute.
A.
2
B. 4 - ...ANSWER...3
C.
