CDL - COMBINATION VEHICLE AND STUDY GUIDE LATEST VERSION THIS YEAR ALL 380 QUESTIONS AND CORRECT DETAILED SOLUTIONS

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CDL - COMBINATION VEHICLE AND STUDY GUIDE
LATEST VERSION THIS YEAR ALL 380 QUESTIONS
AND CORRECT DETAILED SOLUTIONS

CDL - Combination Vehicle Practice Test

Question: A tractor with a(n) ________ trailer requires the shortest amount of stopping
distance .

1. empty

2. fully loaded

3. lightly loaded - CORRECT ANSWER✔✔fully loaded




Question: The air leakage rate for a combination vehicle ( engine off, brakes on) should not be
more than _____ psi per minute .

1. 4

2. 6

3. 2 - CORRECT ANSWER✔✔4




Question: If you do not do the final air brake check for air leaks and fix them before driving,

1. you could lose your brakes while driving

2. your fuel usage will increase

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3. tire pressure will drop - CORRECT ANSWER✔✔you could lose your brakes while driving




Question: Which part of the kingpin should the locking jaws close around? - CORRECT
ANSWER✔✔The shank




Question: Glad hands are used to connect the ....

1. kingpin from the trailer to the locking jaws of the fifth wheel

2. electrical lines from the tractor to the trailer

3. service and emergency air lines from the truck or tractor to the trailer - CORRECT
ANSWER✔✔service and emergency air lines from the truck or tractor to the trailer




Question: Trucks roll over more easily when fully loaded and are

1. ten times more likely to roll over in a crash than empty rigs

2. five times more likely to roll over in a crash than empty rigs

3. two times more likely to roll over in a crash than empty rigs - CORRECT ANSWER✔✔ten times
more likely to roll over in a crash than empty rigs




Question: In general, the higher your trucks center of gravity, the ...

1. easier it is to turn over

2. more stable it is when turning


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3. easier it is to turn around corners - CORRECT ANSWER✔✔easier it is to turn over




Question: You are driving a combination vehicle when the trailer breaks away, pulling apart
both air lines. You would expect the trailer brakes to come on and ...

1. the tractor to lose all air pressure

2. the tractor protection valve to close

3. the trailer supply valve to stay open - CORRECT ANSWER✔✔the tractor protection valve to
close




Question: When you drive a set of doubles, which shut-off valve must be closed in the last
trailer?

1. Middle section

2. front section

3. back section - CORRECT ANSWER✔✔back section




Question: The fifth wheel locking lever is not locked after the jaws close around the kingpin.
This means that...

1. the parking lock is off and you may drive away

2. the trailer will not swivel on the fifth wheel

3. the coupling is not right and should be fixed before you drive the coupled unit - CORRECT
ANSWER✔✔the coupling is not right and should be fixed before you drive the coupled unit

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Question: What gear should the tractor engine be in after you uncouple the trailer and are
inspecting the trailer?

1. neutral

2. low reverse

3. high reverse - CORRECT ANSWER✔✔neutral




Question: After you supply air to the trailer, make sure the air lines are not crossed and the
trailer brakes are working. This is done by ..

1. lifting the brake pedal

2. applying and releasing the trailer brakes and listening for brake sounds

3. turning on the parking brake from the cab - CORRECT ANSWER✔✔applying and releasing the
trailer brakes and listening for brake sounds




Question: If the brakes did not release when you pushed the trailer air supply valve, you should
...

1. cross the air lines,

2. check the air line connections

3. check the electrical cables - CORRECT ANSWER✔✔check the air line connections




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