CDL - Combina on Vehicle Prac ce Test
A tractor with a(n) ________ trailer requires the shortest amount of stopping distance .
1. empty
2. fully loaded
3. lightly loaded
fully loaded
The air leakage rate for a combina!on vehicle ( engine off, brakes on) should not be more
than _____ psi per minute .
1. 4
2. 6
3. 2
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. !re pressure will drop
you could lose your brakes while driving
Which part of the kingpin should the locking jaws close around?
The shank
Glad hands are used to connect the ....
1. kingpin from the trailer to the locking jaws of the fi.h wheel
2. electrical lines from the tractor to the trailer
3. service and emergency air lines from the truck or tractor to the trailer
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 !mes more likely to roll over in a crash than empty rigs
2. five !mes more likely to roll over in a crash than empty rigs
3. two !mes more likely to roll over in a crash than empty rigs
ten !mes 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
easier it is to turn over
You are driving a combina!on 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 protec!on valve to close
3. the trailer supply valve to stay open
the tractor protec!on valve to close
When you drive a set of doubles, which shut-off valve must be closed in the last trailer?
1. Middle sec!on
2. front sec!on
3. back sec!on
back sec!on
The fi.h wheel locking lever is not locked a.er 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 fi.h wheel
3. the coupling is not right and should be fixed before you drive the coupled unit
the coupling is not right and should be fixed before you drive the coupled unit
What gear should the tractor engine be in a.er you uncouple the trailer and are inspec!ng
the trailer?
1. neutral
2. low reverse
3. high reverse
neutral
A.er 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. li.ing the brake pedal
2. applying and releasing the trailer brakes and listening for brake sounds
3. turning on the parking brake from the cab
applying and releasing the trailer brakes and listening for brake sounds
If the brakes did not release when you pushed the trailer air supply valve, you should ...
1. cross the air lines,
A tractor with a(n) ________ trailer requires the shortest amount of stopping distance .
1. empty
2. fully loaded
3. lightly loaded
fully loaded
The air leakage rate for a combina!on vehicle ( engine off, brakes on) should not be more
than _____ psi per minute .
1. 4
2. 6
3. 2
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. !re pressure will drop
you could lose your brakes while driving
Which part of the kingpin should the locking jaws close around?
The shank
Glad hands are used to connect the ....
1. kingpin from the trailer to the locking jaws of the fi.h wheel
2. electrical lines from the tractor to the trailer
3. service and emergency air lines from the truck or tractor to the trailer
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 !mes more likely to roll over in a crash than empty rigs
2. five !mes more likely to roll over in a crash than empty rigs
3. two !mes more likely to roll over in a crash than empty rigs
ten !mes 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
easier it is to turn over
You are driving a combina!on 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 protec!on valve to close
3. the trailer supply valve to stay open
the tractor protec!on valve to close
When you drive a set of doubles, which shut-off valve must be closed in the last trailer?
1. Middle sec!on
2. front sec!on
3. back sec!on
back sec!on
The fi.h wheel locking lever is not locked a.er 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 fi.h wheel
3. the coupling is not right and should be fixed before you drive the coupled unit
the coupling is not right and should be fixed before you drive the coupled unit
What gear should the tractor engine be in a.er you uncouple the trailer and are inspec!ng
the trailer?
1. neutral
2. low reverse
3. high reverse
neutral
A.er 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. li.ing the brake pedal
2. applying and releasing the trailer brakes and listening for brake sounds
3. turning on the parking brake from the cab
applying and releasing the trailer brakes and listening for brake sounds
If the brakes did not release when you pushed the trailer air supply valve, you should ...
1. cross the air lines,
