CDL Subsection 6.1,6.2, 6.3,6.4 & 6.5 Air Brakes

What two things are important to prevent rollover?

Keep the cargo as close to the ground as possible
Drive slowly around turns (curves)

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?

Your trailer can swing out and strike other vehicles that will cause your tractor to jackknife very quickly

What is offtracking?

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is called "offtracking" or " Cheating" .

When you back a trailer, you should position your vehicle so you can back in a curved to the driver side. True or False?

True
Try to position your vehicle so you can back in a straight line. If you must back on a curved path, back to the driver's side so you can see.

What type of trailers can get stuck on railroad highway crossings?

Low -slung units (low boys, car carrier, moving van, possum belly livestock trailer)
Single axle tractor pulling a long trailer with it's landing gear set accommodate a tandern-axle tractor.

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

DO NOT use it in driving because of the danger of making the trailer skid.

Describe what the 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

Describe what the service line is for?

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

What is the emergency air line for?

(Also called the supply line) has two purposes, first it supplies air to the trailer air tanks. Second, the emergency line controls the emergency brakes on combination vehicles.

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

If the trailer does not have spring brakes, use wheel chocks to keep the trailer from moving

Where are the shut-off valves?

Shut off valves (also called cut-out cocks) are used in the service and supply air lines at the back of the trailers used to low other trailers.

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

If the trailer is too high, it may not couple correctly

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

Make sure there is no space between upper and lower fifth wheel

You should look into the back of the fifth wheel to see if it is locked onto the kingpin. True or False?

True
Look into the back and under the trailer

To drive you need to raise the landing gear only until it just lifts off the pavement. True or False?

False
Raise the landing gear all the way up. (Never drive with landing gear only part way up as it may catch on railroad tracks or other things.

How do you know if your trailer is equipped with anti lock brakes?

Look under the vehicle for the ECU and wheel speed sensor wires coming from the back of the brakes

Which shut off valves should be open and which closed?

All shut off valves are in the open position except the ones at the back of the last trailer, which must be closed.

How can you test that air flows to all trailers?

Use the tractor parking brake and/or chock the wheels to hold the vehicle.
Wait for air pressure to reach normal then push in the red "trailer air supply" knob and etc.

How can you test the tractor protection valve?

Charge the trailer air brake system. Shut the engine off. 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 controller place it in "emergency" position. Pull gently on the trailer with the tractor to check that the trailer emergency brakes

How can you test the trailer service brakes?

Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply trailer brakes with the hand control (trolley value) if so equipped.