Combination Vehicles - Full Test Sample, 25 questions
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.
The kingpin is about 1 ¼ inches above the fifth wheel.
The end of the kingpin is even with the top of the fifth wheel.
You should not back a tractor under a trailer until the whole air system is:
Between 60 and 80 PSI.
At normal pressure.
Bled down to half the maximum pressure.
Which part of the kingpin should the locking jaws close around?
The base.
The shank.
The head.
When you get ready to back under the semi-trailer you should line up:
About 12 degrees off the line of the trailer.
The kingpin to engage the driver’s side locking jaw first.
Directly in front of the trailer.
How should you test the tractor semi-trailer connection for security?
Pull gently forward in low gear against the locked trailer brakes, then look at it carefully.
Put the tractor in gear and pull ahead with a sharp jerk.
Rock the trailer back and forth with the trailer brakes locked.
When should you use the hand valve to park a combination vehicle?
To park at loading docks.
Never.
To park on a grade.
You supply air to the trailer tanks by:
Pushing in the trailer air supply valve.
Pulling out the trailer air supply valve.
Connecting the service line glad hand.
Why should you be sure that the fifth wheel plate is greased as required?
To reduce heat and noise.
To prevent steering problems.
To ensure good electrical connections.
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.
Lifting the brake pedal.
Turning on the parking brakes from the cab.
There are two things that a driver can do to prevent a rollover. They are: (1) Keep the cargo as close to the ground as possible; and (2):
Make sure that the brakes are properly adjusted.
Keep the fifth wheel’s free play as tight as possible.
Go slowly around turns.
Before you back under a trailer, make sure the:
Air supply knob is in.
Air brakes are off.
Trailer brakes are locked.
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.
The trailer’s air tank will exhaust through the open line.
The emergency tractor brakes will come on.
The air leakage rate for a combination vehicle (engine off, brakes on) should not be more than ___ PSI per minute.
4
2
6
In normal driving, some drivers use the hand valve before applying the brake pedal to prevent a jackknife. Which of these statements is true?
The hand valve should not be used to slow the vehicle when driving.
The brake pedal will work the trailer spring brakes instead of the air brakes.
The hand valve will apply the tractor brakes instead of the trailer brakes.
Why should you lock the tractor glad hands to each other or use "dummy couplers" when you are not towing a trailer?
The connected brake circuit becomes a backup air tank.
If you did not, you could never build system pressure.
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:
Straight up.
Over the locking lever.
Through the locking lever.
The front trailer supports are up and trailer is resting on the tractor. Make sure:
There is enough clearance between the upper and lower fifth wheel.
The safety latch is in the unlocked position.
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 tank pressure to be lost.
Trailer emergency brakes to come on.
Tractor spring brakes to lock on.
When backing a tractor under a trailer you should expect:
Trailer will be lifted slightly when the tractor backs under it.
End of the kingpin is even with the top of the fifth wheel.
Trailer landing gear is fully extended.
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.
The brake pedal will work the trailer spring brakes instead of the air brakes.
The hand valve will apply the tractor brakes instead of the 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 semi-trailer?
The emergency and service air lines.
The electrical service cable.
Nothing, back up and lock the fifth wheel.
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
Blue, red
Black, yellow
Which of these statements is true?
Light vehicles need more braking power to stop than heavy ones.
Always delay braking a heavy vehicle until you have no other choice.
“Bobtail” tractors can take longer to stop than a combination vehicle loaded to the maximum gross weight.
After connecting the air lines, but before backing under the trailer, you should:
Make sure that the trailer brakes are off.
Supply air to the trailer system, then pull out the air supply knob.
Walk around the rig to make sure it is clear.
The hand valve should be used:
To test the trailer brakes.
Only when the trailer is fully loaded.
Only with the foot brake.
The air leakage rate for a combination vehicle (engine off, brakes off) should be no more than ___ PSI per minute.
2
3
4
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:
You can set the fifth wheel for weight balance.
The coupling is not right and should be fixed before driving the vehicle.
The parking lock is off and you may drive away.
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 trailer supply valve to stay open.
The tractor to lose all air pressure.
The tractor protection valve to close.
Semi-trailers made before 1975 that are equipped with air brakes:
Often do not have spring brakes.
Usually need to a glad hand converter.
Are easier to brake because they are heavier.
Almost half of all truck driver deaths are the result of:
Speed.
Rollovers.
Following too closely.
What statement 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).
Your trailer is half full and the cargo is loaded in the front of the trailer. When you make a sudden steering wheel movement cargo will tend to forcefully slide to the back of the trailer, forcing the trailer to roll over.
When you make a quick lane change or sudden movement with your steering wheel, the tractor tends to rock and sway. The velocity of the rearmost trailer forces the tractor to roll over before the trailer.
Which type of truck-trailer combination has the best chance of the “crack the whip” rollover?
A single tractor-trailer.
A tractor pulling 3 trailers.
A tractor pulling 2 trailers.
Which trailers are most likely to get stuck on railroad tracks? (Select three)
Lowboy trailers. A low slung unit.
Possum-belly livestock trailers. A low slung unit.
Tandem axle tractor pulling a flatbed.
Single axle tractors pulling a short trailer. 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.
Completely cleared from the trailer.
With the fifth wheel directly beneath the kingpin.
Under good driving conditions, you should leave at least one second of space between your vehicle and the vehicle ahead for every ____ feet of your vehicle’s length.
10
20
30
The safest way to make a turn without entering another traffic lane is:
You should turn wide before you start the turn.
You should turn wide as you complete the turn.
You should not make a turn and move to another place where you can make a turn without crossing other lanes.
In general, the higher your truck’s center of gravity, the:
Easier it is to turn around corners.
More stable it is when turning.
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?
The trailer’s tank will exhaust through the open line.
The emergency trailer brakes will come on.
Nothing is likely to happen until you try to apply the brakes.
Glad hands are used to connect the:
Electric lines from the tractor to trailer.
Kingpin from the trailer to the locking jaws of the fifth wheel.
Service and emergency air lines from the truck to the trailer.
A driver crosses the air lines when hooking up to an old trailer. What will happen?
The hand valve will apply the tractor brakes instead of the trailer brakes.
If the trailer has no spring brakes, you could drive away but you wouldn’t have trailer brakes.
The brake lights will come on when the brake pedal is pressed.
The hand valve should be used:
As a parking brake.
Only with a foot brake.
To test the trailer brakes.
When driving a set of doubles it is necessary to close which shut-off valve in the last trailer?
Front.
Back.
Middle section.
Your emergency air line breaks or gets pulled apart while you are driving. The loss of pressure will cause the:
Air compressor to unload instead of pumping air.
Emergency trailer brakes to come on.
Trailer supply valve to open.
How much space should be between upper and lower fifth wheel after coupling?
Just enough to see light through it.
About 1/4 inch.
None.
If the brakes are not released when you pushed the trailer air supply valve you should:
Check air line connection.
Cross the air lines.
Check electrical cable.
You have pushed the trailer air supply valve. You shouldn’t back a tractor under a trailer until the whole air system is:
At normal pressure.
Empty.
Between 60 and 80 PSI.
You are coupling a tractor to a semi-trailer. You have connected the air lines. Before backing under the trailer you should:
Supply air to the trailer system, then pull out the air supply knob.
Pull ahead to test the glad hands connections.
Make sure that the trailer brakes are off.
After you have coupled the trailer you should have to raise the landing gear by using:
Low gear.
Intermediate.
High gear.
When connecting the glad hands press the two seals with the coupler together at what degree to each other?
45 degrees.
90 degrees.
180 degrees.
The trailer is coupled to the tractor and the trailer landing gear is up. Before driving, make sure:
There is enough clearance between the upper and lower fifth wheels.
There is enough clearance between the tractor frame and the landing gear.
The safety latch is in unlocked.
When you are uncoupling a loaded trailer lower the landing gear until it:
Reaches the ground.
Makes contact with the ground and leave the trailer off the fifth wheel.
Makes firm contact with the ground.
When coupling, the proper position of the fifth wheel is:
Level with the ground.
Tilted down toward the end of the tractor.
Tilted up toward the end of the tractor.
Air and electrical lines from the tractor to the trailer should be:
Resting on the frame of the tractor.
Pulled tight with very little slack.
Secured, but with enough slack for turns.
When backing a tractor under a trailer you should:
Do it quickly to ensure that the kingpin is locked into the fifth wheel.
Always use lowest reverse gear.
Always approach the trailer at a slight angle.
Compared to a straight truck or bus there are ____ things to inspect in combination vehicles.
Fewer
The same number
More
While checking if the tractor is securely coupled to the trailer, the landing gear should be:
Fully lowered.
Fully raised.
Slightly raised.
After you lock the kingpin into the fifth wheel, you should check the connection by pulling:
Forward 50 feet, turning right and left.
The tractor ahead gently with the trailer brakes locked.
The tractor ahead sharply to release the trailer brakes.
After the trailer has been coupled to the tractor, the tractor protection control valve should be placed in what position?
Down.
Up.
Normal.
To unlock the fifth wheel, pull the release handle to the _____ position.
Neutral
Open
Closed
Off-tracking or cheating causes which of these to follow the wider pass while making a turn?
53-feet bobtail.
Tractor with a 45-foot trailer.
Tractor with two 27-foot trailers.
To stop a trailer skid you should:
Use the trailer hand brakes.
Countersteer.
Release the brakes.
When should you use the hand valve to park a combination vehicle?
To park at loading docks.
To park on a grade.
Never.
When checking the trailer emergency brakes, the tractor protection control valve should be placed in the ________ position.
Emergency
Normal
Neutral
What gear should the tractor be in after you uncouple from the trailer and are inspecting the trailer supports?
Neutral.
Low reverse.
High reverse.
You are uncoupling a trailer. After you shut off the trailer air supply and lock the trailer brakes, you should:
Begin to lower trailer landing gear.
Immediately put on your tractor parking brakes.
Back up gently to ease pressure on the fifth wheel locking jaws.
Combination vehicles are usually heavier, longer, and require more driving skill than single commercial vehicles.
True
False
More than half of truck driver deaths in crashes are the result of rollovers. Trucks turn over easier when fully loaded and are:
Two times more likely to roll over in a crash than empty rigs.
Five times more likely to roll over in a crash than empty rigs.
Ten times more likely to roll over 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.
The front trailer is twice as likely to turn over as the tractor.
Each trailer is equally likely to turn over as the tractor.
Why should you not use the trailer hand brake to straighten out a jackknifing trailer?
Because the brake handle is too hard to reach.
Because the brakes on the trailer wheels caused the skid in the first place.
Because the brakes on the trailer wheels will not respond to the hand brake.
What is a tractor jackknife?
When you lock up the tires on the trailer and the trailer spins out sideways as the tractor continues to push forward.
When you lock up the drive tires on the tractor and the tractor spins out sideways as the trailer continues to push forward.
Neither of these answers are correct.
You should swing wide to the left before starting a 90 degree turn to the right?
Yes
No
Why should you not use the trailer hand valve while driving?
Because it won’t work as well as the foot brake.
Because you should use the parking brake.
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.
It is a yellow, six-sided knob used to control the tractor protection valve.
It is a device used to keep the trailer behind the tractor.
Describe what the service line is for?
To carry air to the parking brake to control the trailer brakes.
To carry air to a relay valve that allows the trailer brakes to be applied quickly.
To carry air to the cab of the rig to cool it.
What are the other names for the service air line?
Control line or signal line.
Straight line or control line.
Curved line or signal line.
What is the emergency line?
Air lines connecting the parking brake to the trailer brakes.
Air lines that control the emergency brakes of the tractor.
Air lines that control the emergency brakes on combination vehicles.
What is the emergency air line for?
To engage the front brakes of the tractor in case of an emergency.
To engage the trailer brakes in case of an emergency.
To have extra air pressure in case you need it.
Why should you use chocks when parking a trailer without spring brakes?
Because you don’t want the trailer rolling down a hill.
Because if the air pressure leaks away or down, there will be no brakes.
Because some states require chocking of trailer wheels.
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.
1 red flag.
2 red flags.
How long does it take a typical tractor-trailer to clear a single track? A double track?
It takes 10 seconds to clear a single track, and more than 12 seconds to clear a double track.
It takes 7 seconds to clear a single track, and more than 10 seconds to clear 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 is:
Empty.
At normal pressure.
Between 60 and 80 PSI.
The best way to tell if your trailer has started to skid is to:
Hear the wheels skidding.
See it in your mirrors.
Feel for “pulling” in the cab.
Which of these vehicles off-track the most?
5-axle tractor towing a 52-foot trailer.
5-axle tractor towing a 45-foot trailer.
5-axle tractor towing a 42-foot trailer.
A tractor with a(n) ____ trailer requires the shortest amount of stopping distance.
Empty
Lightly loaded
Fully loaded
A trailer is most likely to jackknife when it is:
Loaded to full capacity.
Overloaded.
Empty.
If you have coupled with a semi-trailer, where should the front trailer supports be before driving away?
Raised 1/2 way with the crank handle secured in its bracket.
Raised 3/4 way with the crank handle removed.
Fully raised with the crank handle secured in its bracket.
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:
The trailer will not swivel on the fifth wheel.
The parking lock is off and may drive away.
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?
Low reverse.
Neutral.
High Reverse.
When should you use chocks to park a trailer not equipped with spring brakes?
Never.
Always.
Only when it will be parked on an incline.
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