CDL - COMBINATION VEHICLE
PRACTICE TEST QUESTIONS
WITH COMPLETE SOLUTIONS
QUESTIONS AND ANSWERS
A tractor with a(n) ________ trailer requires the shortest amount of stopping
distance .
1. empty
2. fully loaded
3. lightly loaded. ANSWER -fully loaded
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. ANSWER -4
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
3. tire pressure will drop. ANSWER -you could lose your brakes while driving
Which part of the kingpin should the locking jaws close around?. ANSWER -The
shank
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.
ANSWER -service and emergency air lines from the truck or tractor to the trailer
, 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. ANSWER -ten
times more likely to roll over in a crash than empty rigs
In general, the higher your trucks center of gravity, the ...
1. easier it is to turn over
2. more stable it is when turning
3. easier it is to turn around corners. ANSWER -easier it is to turn over
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. ANSWER -the tractor protection valve to
close
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. ANSWER -back section
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.
ANSWER -the coupling is not right and should be fixed before you drive the
coupled unit
PRACTICE TEST QUESTIONS
WITH COMPLETE SOLUTIONS
QUESTIONS AND ANSWERS
A tractor with a(n) ________ trailer requires the shortest amount of stopping
distance .
1. empty
2. fully loaded
3. lightly loaded. ANSWER -fully loaded
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. ANSWER -4
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
3. tire pressure will drop. ANSWER -you could lose your brakes while driving
Which part of the kingpin should the locking jaws close around?. ANSWER -The
shank
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.
ANSWER -service and emergency air lines from the truck or tractor to the trailer
, 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. ANSWER -ten
times more likely to roll over in a crash than empty rigs
In general, the higher your trucks center of gravity, the ...
1. easier it is to turn over
2. more stable it is when turning
3. easier it is to turn around corners. ANSWER -easier it is to turn over
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. ANSWER -the tractor protection valve to
close
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. ANSWER -back section
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.
ANSWER -the coupling is not right and should be fixed before you drive the
coupled unit
