Combination Flashcards
You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is at the right height when?
It Will be raised slightly when the tractor is backed under it.
You should not back a tractor under a trailer until the whole air system is?
At a normal pressure
Which part of the kingpin should the locking jaws close around?
The Shank
When you get ready to back under the semi trailer you should line up?
Directly in front of the trailer
How should you test the tractor semi trailer connection security?
Pull gently forward in low gear against the locked trailer brakes, then look at it carefully
When should you use the hand valve to park a combination vehicle?
Never
You supply air to the trailer tanks by?
Pushing in the trailer air supply valve
Why should you be sure that the fifth wheel plate is greased as required?
To prevent steering problems
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 breaks and listening for brake sounds
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
Before you back under a trailer, make sure the:
Trailer brakes are locked
If the service air lines 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
The air leakage rate for a combination vehicle (engine off, brakes on) should not be more than ___psi per minute.
4
In normal driving, some driver use the hand valve before applying the brake pedal to prevent a jackknife. Which of these statement is true?
If the trailer has no spring brakes, you can drive away, but you will not have trailer brakes
Why should you lock the tractor glad hands (or dummy couplers) to each other when you are not towing a trailer?
It will keep dirt and water out of the lines
For coupling to be completed, the safety catch for the fifth wheel locking lever must be?
Over the locking lever
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
You have a major leak in the service line and you put on the brakes. Service air pressure will escape and cause the?
Trailer emergency brakes to come on
When backing under a tractor under a trailer you should expect?
Trailer will be lifted slightly when the tractor backs under it
The driver crosses the air lines when hooking up to an old trailer. What will happen?
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 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 semitrailer?
The emergency and service air lines
Aire lines on a combination vehicle are often colored to keep them from getting mixed up. The emergency line is ____; the service line is ____
Emergency Line: Red
Service Line: Blue
“Bobtail” tractors can take longer to stop than a combination vehicle loaded to the maximum gross weight.
True
After connecting the air lines, but before backing under the trailer you should?
Supply air to the trailer system, then pull out the air supply knob
The hand valve should be used?
To test the trailer brakes
The air leakage rate for a combination vehicle (engine off, brakes off) should ben o more than ___psi per minute.
3
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that?
The coupling is not right and should be fixed before driving the vehicle.
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?
The tractor protection valve to close
Semi trailer made before 1975 that are equipped with air brakes
Often do not have spring brakes
Almost half of all truck driver deaths are the result of ?
Rollovers
What sentence best explains “crack the whip effect”?
When you make a quick lane change or sudden movement with your steering wheel the rear trailer tends to swing out. The force of the rear trailer becomes amplified causing it to roll over (rearward amplification)
Which type of truck-trailer combination has the best chance of the “crack the whip” rollover?
A tractor pulling 3 trailers
Which trailers are most likely to get stuck on railroad tracks? (Pick 3)
- Lowbody tailers. A low slung unit
- Possum-belly livestock trailers A low slung unit
- Single axle tractors pulling a short trailers. A low slung unit
Where should the tractor be when you inspect landing gear after uncoupling the trailer?
With the tractor frame under the trailer
Under good driving conditions, you should leave at least one second space between your vehicle and the vehicle ahead for every ______ feet of your vehicles length.
10
The safest way to make turn without entering another traffic lane is?
You should turn wide as you complete the turn
In general, the higher your truck’s center of gravity, the?
Easier it is to turn over
If the service 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
Glad hands are used to connect the?
Service and Emergency air lines from the truck and the trailer
A driver crosses the air lines when hooking up to an old trailer. What will happen?
If the trailer has no spring brakes, you could drive away but you wouldn’t have trailer brakes
The hand valve should be used?
To test the trailer brakes
When driving a set of doubles it is necessary to close which shut-off valve in the last trailer.
Back
Your emergency air line breaks or gets pulled apart while you are driving. The loss of pressure will cause the?
Emergency trailer brakes to come on
How much space should be between upper and lower fifth wheel are coupling?
None
If the brakes are not released when you pushed the trailer air supply valve you should?
Check air line connection
You have pushed the trailer air supply valve. You should not back a tractor under a trailer until the whole air system is?
At normal pressure
You are coupling tractor to a semitrailer. You have connected the airlines. Before backing under the trailer you should?
Supply air to the trailer system, then pull out the air supply knob
After you have coupled the trailer you should have to raise the landing gear by using?
Low gear
When connecting the glad hands press the two seals with the coupler together at what degree to each other?
90 degrees
The iron 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 gears
When you are coupling a loaded trailer lower the landing gear until it?
Makes firm contact with the ground
When coupling, the proper position of the fifth wheel is?
Titled down toward the end of tractor
Air and electrical lines from the tractor to the trailer should be?
Secured, but with enough slack for turns
When backing a tractor under a trailer you should?
Always use lowest reverse gear
Compared to a straight truck or bus there are ____ things to inspect in combination vehicles.
More
You have coupled with a semitrailer. Where should you put the iron trailer supports before driving away?
Fully raised with the crank handle secured in its bracket
While checking if the trailer is securely coupled to the trailer the landing gears should be?
Slightly raised
After you lock the kingpin into the fifth wheel, you should check the connection by pulling?
The tractor ahead gently with the trailer brakes locked
After the trailer has been coupled to the tractor, the tractor protection control valve should be places in what position?
Normal
The tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in the ____ brake line.
Emergency
To unlock the fifth wheel, pull the release handle to the ____position
Open
Off-tracking or cheating causes which of these to follow the wider pass while making a turn?
Triple towing a 45-feet trailer
To stop a trailer skid you should?
Release the brakes
When should you use the hand valve to park a combination vehicle?
Never
When checking the trailer emergency brakes on the tractor protection control valve should be placed in the _____position?
Emergency
What gear should the tractor engine be in after you uncouple in the trailer and are inspecting the trailer supports?
Neutral
You are coupling a trailer. After you shut off the trailer air supply and lock the trailer brakes, you should?
Back up gently and ease pressure on the fifth wheel locking jaws
Combination vehicles are usually heavier, longer and require more driving skill than single commercial vehicles
True
More than half of truck driver deaths in crashes are the result of rollovers. Trucks turn over easier when fully loaded and are?
Ten times more likely to rollover in a crash than empty rigs
When you turn suddenly while pulling doubles, which trailer is most likely to turn over?
The rear trailer is twice as likely to turn over as the tractor
Why should you not use the trailer hand brake to straighten out a jackknifing trailer?
Because the brakes on the trailer wheels cause the skid in the first place
What is the tractor jackknife?
When you lock up the drive tires on the tractor and the tractor spins out sideways as the trailer continuous to push forward
Your should swing wide to the left before starting a 90 degree turn to the right?
No
Why should you not use the trailer hand valve while driving?
Because of the danger of making the trailer skid
Describe what the trailer air supply control does
It is used to supply the trailer with air, shut the air off, and put on the trailer emergency brakes
Describe what the service line is for?
To carry air to a relay valve that allows the trailer brakes to be applied quickly
What are the other names for the Service Air Line?
Control Line and Signal Line
What is the emergency air line?
Air lines that control the emergency brakes on combination vehicles
What is the Emergency Air Line for?
To engage the trailer brakes in the case of air pressure loss.
Why should you use chocks when parking a trailer without spring breaks?
Because of the air pressure leaks away or down, there will be no brakes
When a vehicle is carrying a load at night, which extends four feet or more beyond the rear of the body, there must be ____ at the extreme end of the load
2 Red Lights
How long does it take a typical tractor trailer to clear a single track? A double track?
It takes 14 seconds to clear a single track, and more than 15 seconds to clear a double track
You have pushed in the trailer supply valve. You should not move the tractor until the whole air system?
At Normal pressure
The best way to tell if your trailer has started to skid is to?
See it in your mirrors
Which of these vehicles off-track the most?
5-axle tractor towing a 52-foor trailer
A tractor with a(n) _____ trailer requires the shortest amount if stopping distance
Fully Loaded
A Trailer is most likely to Jackknife when it is?
Empty
If you have coupled with a semitrailer, where should the front trailer supports be before driving away?
Fully raised with the crank handle secured in the bracket
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that?
The coupling is not right and should be fixed before driving the coupled unit
You want to inspect the trailer supports. You should place the tractor transmission in which gear after you have uncoupled the trailer?
Neutral
When should you use chocks to park a trailer not equipped with Spring breaks?
Always
