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.pdf

CDL COMBINATION VEHICLE EXAM, PRACTICE E
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XAM AND STUDY GUIDE NEWEST 2024 ACTUAL EX
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AM 300 QUESTIONS AND CORRECT DETAILED ANS
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WERS WITH (VERIFIED ANSWERS) |ALREADY GRA
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DED A+ n




Why should you lock the tractor glad hands (or dumm
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y couplers) to each other when you are not towing a tr
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ailer?

A. The connected brake circuit becomes a backup air
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tank.
B. If you did not, you could never build system
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pressure.
C. It will keep dirt and water out of the lines. -
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...ANSWER...It will keep dirt and water out of the lines. n n n n n n n n n




For coupling to be completed, the safety catch for the f
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ifth wheel locking lever must be:
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A. Straight up. n



B. Over the locking lever. n n n



C. Through the locking lever. - n n n n



...ANSWER...Over the locking lever.
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The front trailer supports are up and trailer is resting o
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n the tractor. Make sure:
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A. There is enough clearance between the upper and
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lower fifth wheel. n n

,B. The safety latch is in the unlocked position.
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C. There is enough clearance between the tractor fra
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me and the landing gear. -
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n...ANSWER...There is enough clearance between the t n n n n n n



ractor frame and the landing gear.
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You have a major leak in the service line and you put o
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n the brakes. Service air pressure will escape and ca
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use the: n




A. Trailer tank pressure to be lost. n n n n n



B. Trailer emergency brakes to come on. n n n n n



C. Tractor spring brakes to lock on. - n n n n n n



...ANSWER...Trailer emergency brakes to come on. n n n n n




When backing under a tractor under a trailer you shou
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ld expect:
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A. Trailer will be lifted slightly when the tractor backs
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under it. n



B. End of the kingpin is even with the top of the fifth
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wheel. C. Trailer landing gear is fully extended. -
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...ANSWER...Trailer will be lifted slightly when the trac n n n n n n n



tor backs under it.
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The driver crosses the air lines when hooking up to an
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old trailer. What will happen?
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A. If the trailer has no spring brakes, you can drive
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away, but you will not have trailer brakes.
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,B. The brake pedal will work the trailer spring brakes
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instead of the air brakes. n n n n



C. The hand valve will apply the tractor brakes instead
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of the trailer brakes. - ...ANSWER...If the trailer has no
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spring brakes, you can drive away, but you will not ha
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ve trailer brakes.
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You are coupling a tractor to a semi-
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trailer and have backed up but are not under it. What sh
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ould you hook up before backing under the semi-
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trailer?

A. The emergency and service air lines.
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B. The electrical service cable.
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C. Nothing, back up and lock the fifth wheel. - n n n n n n n n



...ANSWER...The emergency and service air lines. n n n n n




Air lines on a combination vehicle are often colored to k
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eep them from getting mixed up. The emergency line is
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____; the service line is ____.
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A. Red, blue n



B. Blue, red n



C. Black, yellow - ...ANSWER...Red, blue n n n n




Which of these statements is true?
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A. Light vehicles need more braking power to stop t
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han heavy ones.
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B. Always delay braking a heavy vehicle until you haven n n n n n n n n



no other choice.
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, C. "Bobtail" tractors can take longer to stop than a
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combination vehicle loaded to the maximum gross n n n n n n



weight. - n



n...ANSWER..."Bobtail" tractors can take longer to stop n n n n n n



nthan a combination vehicle loaded to the maximum gr
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oss weight. n




After connecting the air lines, but before backing unde
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r the trailer, you should:
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A. Make sure that the trailer brakes are off.
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B. Supply air to the trailer system, then pull out the air
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supply knob. n



C. Walk around the rig to make sure it is clear. -
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...ANSWER...Supply air to the trailer system, then pull n n n n n n n n



out the air supply knob.
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The hand valve should be used:
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A. To test the trailer brakes.
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B. Only when the trailer is fully loaded.
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C. Only with the foot brake. - n n n n n



...ANSWER...To test the trailer brakes.
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The air leakage rate for a combination vehicle (engine o
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ff, brakes off) should be no more than ___ PSI per minut
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e.

A. 2 n



B. 3 n



C. 4 - ...ANSWER...3
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