ASD COMBINATION KNOWLEDGE STUDY MATERIAL

This is the study material for the Combination Knowledge test. Please study it until you are comfortable with the material, and then proceed to the practice tests.

The best way to tell if your trailer has started to skid is to*

Feel for "pulling" in the cabHear the wheels skiddingSee it in your mirrors

You have pushed in the trailer supply valve. You should not move the tractor until the whole air system is*

At normal pressureBetween 60 and 80 psiEmpty

Which part of the kingpin should the locking jaws close around?*

The baseThe shankThe head

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*

302010

Which of these vehicles off-track the most?*

5-axle tractor towing a 42-foot trailer5-axle tractor towing a 45-foot trailer5-axle tractor towing a 52-foot trailer

A tractor with a( n ) _____ trailer requires the shortest stopping distance*

Lightly loadedFully loadedEmpty

A trailer is most likely to jackknife when it is*

EmptyOver LoadedLoaded to full capacity

When checking that the trailer is securely coupled to the tractor, the landing gear should be*

Fully loweredFully raisedSlightly raised

If you are coupled with a semitrailer, where should the front trailer supports be before driving away?*

Raised 3/4 way with the crank handle removedRaised 1/2 way with the crank handle secured in its bracketFully raised with the crank handle secured in its bracket

Compared to a straight truck or bus, there are _____ things to inspect on a combination vehicle*

MoreFewerThe same amount of

You want to inspect the trailer supports. You should place the tractor transmission in which gear after you have uncoupled the trailer?*

Low reverseHigh reverseNeutral

There are two things that can prevent a rollover. They are: 1. Keep the cargo as close to the ground as possible; and 2.*

Keep both hands firmly on the steering wheelGo slow around turnsMake sure the brakes are properly adjusted

The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:*

The parking lock is off and may drive awayThe trailer will not swivel on the fifth wheelThe coupling is not right and should be fixed before driving the coupled unit

When you are uncoupling a loaded trailer, lower the landing gear until it*

Makes contact with the ground and lifts the trailer off of the fifth wheelMakes firm contact with the groundJust reaches the ground

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 gearThere is enough clearance between the upper and lower fifth wheelThe safety latch is in the unlocked position

Glad hands are used to connect the*

Kingpin from the tractor to the locking jaws on the glide plateElectric lines from the truck to the trailerService and emergency air lines from the truck to the trailer

How much space should be between the upper and lower fifth wheel after coupling?*

Just enough to see light through itNoneAbout 1/4 inch

You should not back a tractor under a trailer until the whole air system is*

At normal pressureEmptyBetween 60 and 80 psi

You are coupling a semitrailer to your tractor but have not backed under it. The trailer is at the right height when*

The kingpin is about 1 1/4 inches above the fifth wheelIt is raised slightly when the tractor is backed under itThe end of the kingpin is even with the top of the fifth wheel

When checking the trailer's emergency brakes, the tractor protection control valve should be placed in the ______ position*

EmergencyNeutralNormal

Which statement is true?*

Vehicles need more braking power to stop than heavy oneBobtail tractors can take longer to stop than a combination vehicle loadedThe brake and suspension systems of combination vehicles work best with a light load

In general, the higher your truck's "center of gravity" the*

Easier it is to turn overEasier it is to turn around cornersMore stable it is when turning

You are coupling a tractor to a semitrailer. You have backed up but are not under it. What should you hook up before backing under the semitrailer*

Nothing. Back up and lock the fifth wheel.The electrical service cableThe emergency and service air lines.

Air and electric lines from the tractor to the trailer should be*

Secured but with enough slack for turnsResting on the frame of the tractorPulled tight, with very little slack

If you cannot make a turn without entering another traffic lane, you should*

Not make that turnTurn wide before you start your turnTurn wide as you complete your turn

When should you use chocks to park a trailer not equipped with spring brakes?*

Only when it will be parked on an inclineNeverAlways

When coupling, the proper position of the fifth wheel is*

Tilted down towards the end of the tractorLevel with the groundTilted up towards the end of the tractor

To stop a trailer skid you should*

CountersteerUse the trailer hand brakeRelease the brake

After you lock the kingpin into the fifth wheel, you should check the connection by pulling*

The tractor ahead gently with the trailer brakes lockedForward 50 feet, turning right, and leftThe tractor ahead sharply to release the trailer brakes

You are uncoupling a trailer. After you shut off the trailer air supply and lock the trailer brakes, you should*

Immediately put on your tractor parking brakesBack up gently to ease pressure on the fifth wheel locking jawsBegin to lower the trailer landing gear

To unlock the fifth wheel, pull the release handle to the _________ position*

ClosedNeutralOpen

For a coupling to be completed, the safety catch for the fifth wheel locking lever must be*

Straight upOver the locking leverThrough the locking lever

Before you back a under a truck trailer, make sure the*

Air supply knob is inAir brakes are offTrailer brakes are locked

After you connect the air lines, but before you back under the trailer, you should*

Make sure the trailer brakes are offWalk around the rig to be sure it is clearSupply air to the trailer system, then pull out the supply knob

Why should you be sure that the fifth wheel plate is greased as required?*

To prevent steering problemsTo reduce heat and noiseTo ensure good electrical connections

After the trailer has been coupled to the tractor, the tractor protection control valve should be placed in the _______ position*

UpDownNormal

After you have coupled the trailer, you should begin raising the landing gear by using the ________ gear.*

Mid levelLowHigh

When backing a tractor under a trailer you should*

Do it quickly to ensure that the kingpin is locked into the fifth wheelAlways approach the trailer at a slight angleAlways use the lowest reverse gear

Why should you lock the air line glad hands to each other (or dummy couplers) when you are not towing a trailer?*

It will keep water out of the linesIf you do not, you could never build system pressureThe connected brake circuit becomes a back up air tank

When you get ready to back under a semitrailer, you should line up*

The left rear outside dual wheel with the kingpinThe kingpin with the edge of the driver's side locking jawDirectly in front of the trailer

After you supply air to the trailer, make sure the air lines are not crossed and the trailer brakes are working. You do this by*

Applying/releasing the trailer brakes and listening for brake soundsTurning on the parking brakes from the cabWatching your mirrors to see if the trailer lights come on

When should you get out of your vehicle when backing with a trailer?*

Never get out of your vehicleWhen you are unsure of your path of travelWhen your trailer begins to drift on the passenger side

What should you do if your vehicle gets stuck on a raised railroad-highway crossing?*

Turn on your four-way flashersUse reverse gear to back up off the crossingGet out of the vehicle and get away from the tracks

Semitrailers made before 1975 that are equipped with air brakes:*

Usually need a glad hand converterHave only a service air lineOften do not have spring brakes

When should you use the hand valve to park a combination vehicle?*

NeverTo park at loading docksTo park on a grade

The hand valve should be used:*

As a parking brakeOnly with the foot brakeTo test the trailer brakes

You are driving a combination vehicle. If the service air line comes apart but the emergency line stays together, what will happen right away?*

The trailer's air tank will exhaust through the open lineNothing is likely to happen until you try to apply the brakesThe emergency trailer brakes will come on

Air lines on a combination vehicle are often colored to keep from getting them mixed up. The emergency line is ______; The service line is ______.*

Black; YellowRed; BlueBlue; Red

When connecting the glad hands, press the two seals of the couplers together at a degree angle to one another*

9018045

You supply air to the trailer tanks by:*

Pulling out the trailer air supply control valvePushing in the trailer air supply control valveConnecting the service line glad hand

The trailer air supply control (or tractor protection valve control) should automatically close when the air pressure falls to between ________ psi*

20 and 45100 and 12560 and 85

You are driving a combination vehicle. The trailer breaks away and pulls apart both air lines. You would expect the trailer brakes to come on and the:*

Tractor protection valve to closeTrailer supply valve to stay openTractor to lose all air pressure

What will happen if the air lines are crossed when you hook up to an old trailer?*

If the trailer has no spring brakes, you could drive away but you would not have trailer brakesThe brake lights will not come on when you press the brake pedalThe hand valve will apply the tractor brakes instead of the trailer brakes

When driving a set of doubles, it is necessary to close the _______ shut-off valve in the last trailer*

FrontMid-sectionBack

Loss of air pressure in the emergency line causes:*

The trailer's emergency brakes to come onAn increase in air pressure to the service lineThe relay valves to close

You have a major leak in the service line and you put on the brakes. Service air pressure will escape and cause the:*

Tractor spring brakes to lock onTrailer emergency brakes to come onTrailer take pressure to be lost

This is the study material for the Combination Knowledge test. Please study it until you are comfortable with the material, and then proceed to the practice tests.

ASD Combination Study Material