CDL COMBINATION VEHICLES

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TREU OR FALSE:

More than half of truck driver deaths in crashes are the result of truck rollovers.

True

Fully loaded rigs are ___ times more likely to roll over in a crash than empty rigs.

10

What can you do to prevent rollovers?

keep the cargo close to the ground

drive slowly around turns

TRUE OR FALSE:

Keeping cargo low is even more important in combination vehicles than in straight trucks.

True

Rollovers happen when you turn too___

Fast

Trucks with trailers have a dangerous...

crack the whip effect

TRUE OR FALSE:

When pulling trailers, a sudden movement with your steering wheel may cause your tralier to tip over.

True

Large combination vehicles take longer to stop when they are...

Empty

How much follwoing distance should you have?

At leats 1 second for every 10 feet of vehicle length under 40 mph.

How much following distance should you have driving 50 mph?

At least 1 second for every 10 feet of your vehicle plus an additional second.

When lightly loaded, the very stiff suspension springs and strong brakes give poor traction.

True

TRUE OR FALSE:

Tests have shown that bobtails are easy to stop.

False

In any combination rig, allow lots of ___ distance and look far ahead.

Following

What is the best way to recognize that the trailer has started to skid?

Seeing it in your mirriors.

TRUE OR FALSE:

When braking hard you should check your mirriors to make sure that your trailer is staying where it should?

True

Why should you not use the trailer hard brake to straighten out a jackknifing trailer.

This is the wrong thing to do since the brakes on the trailer wheels caused the skid in the first place.

Once the trailer wheels grip the road again, the trailer will start to follow the tractor and starighten out.

What is off tracking?

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels.

Longer vehicles will off track more.

TRUE OR FALSE:

If you must back on a curved path, back to the drivers side so you can see.

True

What type of trailers can get stuck on rail-road highway crossing?

Lowboy

Car Carrier

Why should you not use the trailer hand valve while driving?

The trailer hand valve should only be used to test the brakes.

Do not use it in driving because of the danger of making the trailer skid.

Describe what trailer air supply control does.

You push it in to supply the trailer with air, and pull it out to shut the air off and put on the trailer emergency brakes.

The valve will pop out ( closing the tractor protection valve ) when the air pressure drops into the range of 20-45 psi.

Describe what the service line is for.

The service line ( called the control line ) carries air, which is controlled by the foot brake or the trailer hand brake.

Depending on how hard you press the foot brake or hand valve, the pressure in the service line will similarily change.

What does the emergency air line do?

It supplies air to the trailer air tanks

Loss of air pressure in the emergency line causes the trailer emergency brakes to come on.

TRUE OR FALSE:

Blue is used for the service line and red for the emergency.

True

Why should you use chocks when parking a trailer without spring brakes.

Eventually, the air will leak away and there will be no brakes.

Where are shut-off valves?

In the back of the trailer.

TRUE OR FALSE:

You may not notice a major leak in the service line until you try and put on the brakes.

True

TRUE OR FALSE:

All new trailers and converter dollies are requirered to have anti-lock brakes.

True

TRUE OR FALSE:

ABS will increase your stopping distance.

False

TRUE OR FALSE:

Trailers will have yellow ABS malfunction lamps on the right side of the trailers.

False

When you drive a tractor-trailer combination with ABS, you should...

Brake as you always have.

TRUE OR FALSE:

If your ABS malfunctions, you will loose your brakes

False

TRUE OR FALSE:

ABS makes it possible to drive faster more safely.

False

When coupling you should inspect the 5th wheel which will include...

Grease on the 5th wheel plate

5th wheel in proper position and tilted down toward the rear of the tractor, with jaws open

When coupling, the tractor should be...

Directly infornt of the trailer.

When coupling you should back...

slowly

How do you know if the trailer is at proper height?

The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it.

When coupling, you should back using...

The lowest reverse gear

How do you check for a secure connection?

Pull tractor gently while the trailer brakes are still locked to check that the trailer is locked on the trcator.

What might happen if the trailer is too high when you try to couple.

You will miss and not get a coupling.

After coupling, how much space should be between the upper and lower 5th wheel?

None

TRUE OR FALSE:

You should look into the back of the 5th wheel to see if it is locked into the kingpin.

True

TRUE OR FALSE:

To drive, you need to raise the landing gear only until it just lifts off the pavement.

False

How can you test that air flows to all trailers?

Go to the rear of the rig. Open the emergency line shut-off valve at the rear of the last trailer.

You should hear air escaping, showing the entire system is charged.

How can you test the tractor-protection valve?

Push in the "air supply" knob, step on and off the brake pedal several times to reduce the air pressure in the tanks.

How can you test the trailer emergency brakes?

Charge the trailer air brake system and check that the trailer rolls freely.

Then stop and pull out the trailer air supply control ( also called tractor protection valve )

How can you test the trailer service brakes?

At normal air pressure, release the parking brakes. Move the vehicle forward slowly, and apply trailer hand brake.

TRUE OR FALSE:

The tractor protection valve will pop when the pressure falls to 100 psi

False

TRUE OR FALSE:

The tractor protection valve will pop when the pressure falls between 20-45 psi.

True

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