CDL - Combination Vehicle Practice Test (2) CDL - Combination Vehicle Practice Test (2) 2/18/2026
CDL - Combination Vehicle Practice Test
fully loaded - ANS-A tractor with a(n) ________ trailer requires the shortest amount of stopping
distance .
1. empty
2. fully loaded
3. lightly loaded
4 - ANS-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
you could lose your brakes while driving - ANS-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
The shank - ANS-Which part of the kingpin should the locking jaws close around?
service and emergency air lines from the truck or tractor to the trailer - ANS-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
ten times more likely to roll over in a crash than empty rigs - ANS-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
easier it is to turn over - ANS-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
the tractor protection valve to close - ANS-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
Page 1 CDL - Combination Vehicle Practice Test (2).pdf
, CDL - Combination Vehicle Practice Test (2) CDL - Combination Vehicle Practice Test (2) 2/18/2026
2. the tractor protection valve to close
3. the trailer supply valve to stay open
back section - ANS-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
the coupling is not right and should be fixed before you drive the coupled unit - ANS-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
neutral - ANS-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
applying and releasing the trailer brakes and listening for brake sounds - ANS-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
check the air line connections - ANS-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
trailer emergency brakes to come on - ANS-You have a major leak in the service line, and you
apply the brakes. Service air pressure will escape and cause the
1. trailer tank pressure to be lost
2. trailer emergency brakes to come on
3. tractor spring brakes to lock on
back up gently to ease pressure on the fifth wheel locking jaws - ANS-You are uncoupling a
trailer. After you shut off the trailer air supply and lock the trailer brakes, you should
1. immediately apply your tractor parking brakes
2. begin to lower the trailer landing gear
Page 2 CDL - Combination Vehicle Practice Test (2).pdf
CDL - Combination Vehicle Practice Test
fully loaded - ANS-A tractor with a(n) ________ trailer requires the shortest amount of stopping
distance .
1. empty
2. fully loaded
3. lightly loaded
4 - ANS-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
you could lose your brakes while driving - ANS-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
The shank - ANS-Which part of the kingpin should the locking jaws close around?
service and emergency air lines from the truck or tractor to the trailer - ANS-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
ten times more likely to roll over in a crash than empty rigs - ANS-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
easier it is to turn over - ANS-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
the tractor protection valve to close - ANS-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
Page 1 CDL - Combination Vehicle Practice Test (2).pdf
, CDL - Combination Vehicle Practice Test (2) CDL - Combination Vehicle Practice Test (2) 2/18/2026
2. the tractor protection valve to close
3. the trailer supply valve to stay open
back section - ANS-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
the coupling is not right and should be fixed before you drive the coupled unit - ANS-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
neutral - ANS-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
applying and releasing the trailer brakes and listening for brake sounds - ANS-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
check the air line connections - ANS-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
trailer emergency brakes to come on - ANS-You have a major leak in the service line, and you
apply the brakes. Service air pressure will escape and cause the
1. trailer tank pressure to be lost
2. trailer emergency brakes to come on
3. tractor spring brakes to lock on
back up gently to ease pressure on the fifth wheel locking jaws - ANS-You are uncoupling a
trailer. After you shut off the trailer air supply and lock the trailer brakes, you should
1. immediately apply your tractor parking brakes
2. begin to lower the trailer landing gear
Page 2 CDL - Combination Vehicle Practice Test (2).pdf
