Combination Vehicles
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This will test knowledge of Combination Vehicles.
- 1.You should not back a tractor under a trailer until the whole air system is:
- A.
At normal pressure
- B.
Bled down to half the maximum pressure
- C.
Between 60-80 psi
- D.
Empty
- 2.Before you back under a trailer, make sure the:
- A.
Trailer brakes are locked
- B.
Tractor protection valve is normal
- C.
Air brakes are off
- D.
Air supply knob is in
- 3.You are coupling a semi-trailer to your tractor but have not yet backed under. The trailer is at the right height when:
- A.
The kingpin is about 1 1/4" inches above the fifth wheel
- B.
The end of the kingpin is even with the top of the fifth wheel
- C.
It will be raised slightly when the tractor is backed under it
- D.
The trailer landing gear are fully extended
- 4.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?
- A.
The electrical service cable
- B.
The emergency and service air lines
- C.
Nothing. Back up and lock the fifth wheel
- D.
The ground cable
- 5.When you get ready to back under the semi-trailer you should line up:
- A.
About 12 degrees off the line of the trailer
- B.
The kingpin to engage the driver's side locking jaw first
- C.
Directly in front of the trailer
- D.
The left rear outer dual wheel with the kingpin
- 6.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?
- A.
The emergency tractor bakes will come on
- B.
The trailer's air tank will exhaust through the open line
- C.
Nothing is likely to happen until you try to apply the brakes
- D.
The emergency trailer brakes will come on
- 7.Which part of the kingpin should the locking jaws close around?
- A.
The shank
- B.
The head
- C.
The base
- D.
It does not matter
- 8.The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:
- A.
You can set the fifth wheel for weight balance
- B.
The parking lock is off and you can drive away
- C.
The coupling is not right and should be fixed before driving the coupled unit
- D.
The trailer will not swivel on the fifth wheel
- 9.How should you test the tractor semi-trailer connection for security?
- A.
Put the tractor in gear and pull ahead with a sharp jerk
- B.
Pull gently forward in low gear against the locked trailer brakes. Then look at it carefully.
- C.
Rock the trailer back and forth with the trailer brakes locked
- D.
Look at it carefully
- 10.The air leaking rate for a combination vehicle (engine off, brakes on) should be less than ___ psi per minute?
- A.
1
- B.
2
- C.
3
- D.
4
- 11.When should you use the hand valve to park a combination vehicle?
- A.
To park at loading docks
- B.
To park on a grade
- C.
Never
- D.
To park for less then two hours
- 12.You have coupled with a semi-trailer. In what position should you put the front trailer supports before driving away?
- A.
Raised 1/2 way with the crank handle removed
- B.
Fully raised with the crank handle secured in it's bracket
- C.
Three turns off the top with the crank handle secured in its bracket
- D.
Raised 3/4 way with the crank handle removed
- 13.You supply air to the trailer tanks by:
- A.
Pushing in the trailer air supply valve
- B.
Pulling out the trailer air supply valve
- C.
Connecting the service line glad hand
- D.
Applying the trailer hand valve
- 14.In normal driving, some drivers use the hand valve before applying the brake pedal to prevent jackknife. Which of these statements is true.
- A.
It should not be done
- B.
It results in less skidding than using the brake alone
- C.
It is the best way to brake and keep the truck in a straight line
- D.
It lets the driver steer with both hands
- 15.The air leakage rate for a combination vehicle (engine off, brakes on) should be less than ___ psi per minute.
- A.
1
- B.
2
- C.
3
- D.
4
- 16.Why should you be sure that the fifth wheel plate is greased as required?
- A.
To ensure good electrical conditions
- B.
To prevent steering problems
- C.
To reduce heat and noise
- D.
To keep the brake system in place
- 17.A driver crosses the airlines when hooking up to an old trailer. What will happen?
- A.
If the trailer has no spring brakes, you can drive away
- B.
The hand valve will apply the tractor brakes instead of the trailer brakes
- C.
The brake pedal will work the trailer spring brakes instead of the air brakes
- D.
The brake lights will not come on when the brake pedal is pressed
- 18.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:
- A.
Turning on the parking brakes from the cab
- B.
Applying and releasing the trailer brakes and listening for brake sounds
- C.
Lifting the brake pedal
- D.
Watching your mirrors to see if the trailer lights come on
- 19.Air lines on a combination vehicle are often colored to keep them from getting mixed up. The emergency line _____; the service line is _____.
- A.
Red / Blue
- B.
Black / Yellow
- C.
Blue / Red
- D.
Orange / Black
- 20.There are two things that a driver can do to prevent a rollover. The are; (1) Keep the cargo as close to the ground as possible; and (2):
- A.
Make sure the brakes are properly adjusted
- B.
Go slowly around turns
- C.
Keep the fifth wheel's free play as tight as possible
- D.
Keep both hands firmly on the steering wheel
- 21.Which of these statements is true?
- A.
Always delay braking a heavy vehicle until you have no other choice
- B.
Light vehicles need more braking power to stop than heavy ones
- C.
"BOBTAIL" tractors can take longer to stop than a combination vehicle loaded to the maximum gross weight.
- D.
The brake and suspension systems of comb. vehicles work best with a light load.
- 22.Semi-trailers made before 1975 that are equipped with air brakes;
- A.
Are easier to brake because they are heavier
- B.
Usually need a glad hand converter
- C.
Ofter do not have spring brakes
- D.
Can not be legally operated on interstate highways
- 23.Why should you lock the tractor glad hands ( or dummy couplers) to each other when you are not towing a trailer?
- A.
The connected brake circuit becomes a back-up air tank
- B.
It will keep dirt and water out of the lines
- C.
If you did not, you could never build system pressure
- D.
All of the above
- 24.The hand valve should be used:
- A.
Only with the foot brake
- B.
To test the trailer brakes
- C.
Only when the trailer is fully loaded
- D.
As a parking brake
- 25.The safety catch for the fifth wheel locking lever must be ___ for a coupling to be complete.
- A.
Over the locking lever
- B.
Under the locking lever
- C.
Through the locking lever
- D.
Straight up
- 26.You are coupling a tractor and semi-trailer and have connected the air lines. Before backing under the trailer, you should:
- A.
Supply air to the trailer system, then pull out the air supply knob to lock the trailer brakes
- B.
Make sure that the trailer brakes are off
- C.
Apply the brakes twice to alert others
- D.
Pull ahead to test the glad hand connections
- 27.The front trailer supports are up and the trailer is resting on the tractor. Make sure:
- A.
There is enough clearance between the tops of the tractor tires and nose of trailer
- B.
There is enough clearance between the tractor frame and the landing gear
- C.
Both A and B are correct
- D.
Neither A and B are correct
- 28.Your emergency air line breaks or gets pulled apart while you are driving. The lose of pressure will cause the:
- A.
Emergency trailer brakes to come on
- B.
Air compressor to unload instead of pumping air
- C.
Tractor supply valve to open
- D.
Tractor air to dump into the trailer tank through the service line
- 29.You have a major leak in the service line and you put on the service brakes. Service air pressure will escape and cause the:
- A.
Trailer emergency brakes to come on
- B.
Trailer tank pressure to be lost
- C.
Tractor spring brakes to be locked on
- D.
Trailer's tank pressure to go to the tractor's system
- 30.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:
- A.
The tractor to loose all air pressure
- B.
The tractor protection valve to close
- C.
The trailer supply valve to stay open
- D.
None of the above
- 31.You are about to back a tractor under a semi-trailer. The trailer is at the right height when the:
- A.
Trailer landing gear is fully extended
- B.
End of the kingpin is even with the top of the fifth wheel
- C.
Trailer will be lifted slightly when the tractor backs under it
- D.
Kingpin is about 1 1/4 inches above the fifth wheel
- 32.How much space should be between the upper and lower fifth wheel after coupling?
- A.
At least 1/2 inch
- B.
None
- C.
Just enough to see light through it
- D.
About 1/4 inch
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