CDL COMBINATION TEST QUESTIONS
AND ANSWERS
b If you cross connect the two air lines the following will result - You will not have air going to the trailer
brakes
You have coupled with a semi-trailer. In what position should you put the front trailer supports before
driving away? - Fully raised with the crank handle secured in its bracket
Th trailer air supply control: - Is a red, eight sided knob
A device which connects the service and emergency air lines from the truck to the trailer is called.. - Glad
hands
If one of the glad hands on your blue air line is missing a seal: - You might end up with a service line air
leak
In order to supply air to the trailer, you must first: - Stop engine so you can hear the brakes
The hand valve should be used: - To test the trailer brakes
The air leakage rate for a combination vehicle (engine off, brakes on) should not be more than _______
psi per minute - 4
When should you use the hand valve to park a combination vehicle? - Never
When you get ready to back under the semi-trailer you should line up - Directly in front of the trailer
If the service air line comes apart while you are driving a combination vehicle but the emergency line
stays together, what will happen right away - Nothing is likely to happen until you try to apply the brakes
When uncoupling, if you park the trailer at an angle... - You could do damage to the landing gear
Which of these statements is true? - "Bobtail" tractors can take longer to stop than a combination
vehicle loaded to the maximum gross weight
In normal driving, some drivers use the hand valve before applying the brake pedal to prevent a
jackknife. Which of these statements is true? - It should not be done
When you inspect the coupling, check to ensure that: - There's a little slack in the air lines
When backing under a tractor under a trailer you should expect: - Trailer will be lifted slightly when the
tractor back under it
A king pin is: - A pin which locks the trailer to the tractor on the fifth wheel
The safety catch for the fifth wheel locking level must be ______ for a coupling to be complete. - Over
the locking lever
, The air leakage rate for a combination vehicle (engine off, brakes off) should be no more than _____ psi
per minute. - 3
You are coupling a tractor to a semi-trailer and have backed up but are not under it. What should you
hook up before backing under? - The emergency and service air lines
Air lines on a combination vehicle are often colored to keep them from getting mixed up. The emergency
line is ____; the service line is _____. - Red, blue
You should not back a tractor under a trailer until the whole air system is: - At normal pressure
Large combination vehicles take longer to stop: - When they are empty
In order to inspect the coupling, you should: - Use a flashlight if necessary
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: - Applying and releasing the trailer brakes and listening for brake sounds; and
also by lifting the brake pedal
The front trailer supports are up and the trailer is resting on the tractor. Make sure: - There is enough
clearance between the tractor frame and the landing gear and that there is enough clearance between
the tops of the tractor tires and the nose of the trailer
You can damage the landing gear if you: - Back under the trailer at an angle
After you supply air to the trailer, make sure the airlines are not crossed and the trailer brakes are
working. This is done by: - Applying and releasing the trailer brakes and listening for brake sounds
When rolling up the landing gear to complete the coupling process: - Grease the landing gear to speed
up the process
There are two things that a driver can do to prevent a roll over. They are: (1) keep the cargo as close to
the ground as possible; and (2): - Go slowly around turns
Why should you be sure that the fifth wheel plate is greased as required? - To prevent steering problems
When coupling the glad hands, you should NOT do the following: - Cross air supply lines to test them for
leaks
If one of the glad hands on your blue air line is missing a seal: - You might end up with a service line air
leak
Before you back under a trailer, make sure the: - Trailer brakes are locked
The driver crosses the air lines when hooking up to an old trailer. What will happen? - If the trailer has no
spring brakes, you can drive away, but you will not have trailer brakes
You supply air to the trailer tanks by: - Pushing the trailer air supply valve
You should crank the landing gear until: - It is as far up as it will go
When uncoupling, it's generally good practice to: - Couple the glad hands together; Couple the glad
hands to dummy couplers; Hag the electrical cable with the plug end down
AND ANSWERS
b If you cross connect the two air lines the following will result - You will not have air going to the trailer
brakes
You have coupled with a semi-trailer. In what position should you put the front trailer supports before
driving away? - Fully raised with the crank handle secured in its bracket
Th trailer air supply control: - Is a red, eight sided knob
A device which connects the service and emergency air lines from the truck to the trailer is called.. - Glad
hands
If one of the glad hands on your blue air line is missing a seal: - You might end up with a service line air
leak
In order to supply air to the trailer, you must first: - Stop engine so you can hear the brakes
The hand valve should be used: - To test the trailer brakes
The air leakage rate for a combination vehicle (engine off, brakes on) should not be more than _______
psi per minute - 4
When should you use the hand valve to park a combination vehicle? - Never
When you get ready to back under the semi-trailer you should line up - Directly in front of the trailer
If the service air line comes apart while you are driving a combination vehicle but the emergency line
stays together, what will happen right away - Nothing is likely to happen until you try to apply the brakes
When uncoupling, if you park the trailer at an angle... - You could do damage to the landing gear
Which of these statements is true? - "Bobtail" tractors can take longer to stop than a combination
vehicle loaded to the maximum gross weight
In normal driving, some drivers use the hand valve before applying the brake pedal to prevent a
jackknife. Which of these statements is true? - It should not be done
When you inspect the coupling, check to ensure that: - There's a little slack in the air lines
When backing under a tractor under a trailer you should expect: - Trailer will be lifted slightly when the
tractor back under it
A king pin is: - A pin which locks the trailer to the tractor on the fifth wheel
The safety catch for the fifth wheel locking level must be ______ for a coupling to be complete. - Over
the locking lever
, The air leakage rate for a combination vehicle (engine off, brakes off) should be no more than _____ psi
per minute. - 3
You are coupling a tractor to a semi-trailer and have backed up but are not under it. What should you
hook up before backing under? - The emergency and service air lines
Air lines on a combination vehicle are often colored to keep them from getting mixed up. The emergency
line is ____; the service line is _____. - Red, blue
You should not back a tractor under a trailer until the whole air system is: - At normal pressure
Large combination vehicles take longer to stop: - When they are empty
In order to inspect the coupling, you should: - Use a flashlight if necessary
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: - Applying and releasing the trailer brakes and listening for brake sounds; and
also by lifting the brake pedal
The front trailer supports are up and the trailer is resting on the tractor. Make sure: - There is enough
clearance between the tractor frame and the landing gear and that there is enough clearance between
the tops of the tractor tires and the nose of the trailer
You can damage the landing gear if you: - Back under the trailer at an angle
After you supply air to the trailer, make sure the airlines are not crossed and the trailer brakes are
working. This is done by: - Applying and releasing the trailer brakes and listening for brake sounds
When rolling up the landing gear to complete the coupling process: - Grease the landing gear to speed
up the process
There are two things that a driver can do to prevent a roll over. They are: (1) keep the cargo as close to
the ground as possible; and (2): - Go slowly around turns
Why should you be sure that the fifth wheel plate is greased as required? - To prevent steering problems
When coupling the glad hands, you should NOT do the following: - Cross air supply lines to test them for
leaks
If one of the glad hands on your blue air line is missing a seal: - You might end up with a service line air
leak
Before you back under a trailer, make sure the: - Trailer brakes are locked
The driver crosses the air lines when hooking up to an old trailer. What will happen? - If the trailer has no
spring brakes, you can drive away, but you will not have trailer brakes
You supply air to the trailer tanks by: - Pushing the trailer air supply valve
You should crank the landing gear until: - It is as far up as it will go
When uncoupling, it's generally good practice to: - Couple the glad hands together; Couple the glad
hands to dummy couplers; Hag the electrical cable with the plug end down
