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.
Why should you not use the trailer hand brake to straighten out a jackknifing trailer?
The brakes on the trailer wheels cause the skid -- release so the trailer wheels will grip the road again.
What is off-tracking?
When a vehicle goes around a corner and the rear wheels follow a different path than the front wheels.
When you back a trailer, you should position your vehicle so you can back in a curved path to the drivers side. True or False?
True
What type of trailers can get stuck on railroad-highway crossings?
Low slung units (lowboy, car carrier, moving van, possum-belly livestock trailer)
Single-axle tractor pulling a long trailer with its landing gear set to accommodate a tandem-axle tractor.
Why should you not use the trailer hand valve while driving?
Danger of making the trailer skid.
Describe what the trailer air supply control does.
Push in -- Supply air to trailer
Push out -- Shut air off and put on trailer emergency brakes.
Describe what the service line is for.
Carries air, which is controlled by the foot brake or the trailer hand brake.
What is the emergency air-line for?
Supplies air to the trailer air tanks
Controls the emergency brakes on combination vehicles
Why should you use chocks when parking a trailer without spring brakes?
To keep the trailer from moving
Where are shut-off valves?
Shut-off valves (also called cut-out cocks) are used in the service and supply air-lines at the back of trailers used to tow other trailers.
What might happen if the trailer is too high when you try to couple?
It may not couple correctly.
After coupling, how much space should be between the upper and lower fifth wheel?
No space
You should look into the back of the fifth even to see if it is locked into kingpin. True or False?
True
To drive you need to raise the landing gear only until it just lifts off the pavement. True or False?
False
How do you know if your trailer is equipped with antilock brakes?
Trailers will have yellow ABS malfunction lamps on the left side, either on the front or rear corner.
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?
Emergency line valve - closed
Service line valve - closed
Shut-off valves to trailers and dolly(ies) - open
How can you test that air flows to all trailers?
Open the service line valve to check that service pressure goes through all the trailers.
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 control, or place it in the "emergency" position. Pull gently on the trailer with the tractor to check that the trailer emergency brakes are on.
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 valve)
What is a converter dolly?
a coupling device of one or two axles and a fifth wheel by which a semitrailer can be coupled to the rear of a tractor- trailer combination forming a double bottom rig.
Do converter dollies have spring brakes?
Yes
What three methods can you use to secure a second trailer before coupling ?
3. 1)Connect the emergency line, charge the trailer air tank, and disconnect the emergency line. 2) Spring brakes. 3) Wheel chocks.
How do you check to make sure trailer height is correct before coupling ?
It must be slightly lower than the center of the fifth wheel, so trailer is raised slightly when dolly is pushed under.
What do you check when making a visual check of coupling?
No space between upper and lower fifth wheel.
Locking jaws closed on kingpin.
Why should you pull a dolly out from under a trailer before you discount it from the trailer in front?
The dolly tow bar may fly up, possibly causing injury, and making it very difficult to re-couple.
What should you check for when inspecting the converter dolly? The pintle hook?
Converter dolly air tank drain valve: CLOSED.
Be sure air-lines are supported and glad hands are properly connected.
If spare tire is carried on converter gear (dolly), make sure it's secured.
Be sure pintle-eye of dolly is in place in pintle hook of trailer(s).
What should you check for when inspecting the pintle hook?
Make sure pintle hook is latched.
Should the shut-off valves on the rear of the last trailer be open or closed?
Closed
Should the shut-off valves on the first trailer in a set of doubles be opened or closed?
Opened
Should the shut-off valves on the middle
trailer of a set of triples be opened or closed?
Opened
How can you test that air flows to all trailers?
Wait for air pressure to reach normal, then push in the red "trailer air supply" knob. This will supply air to the emergency (supply) lines. Use the trailer handbrake to provide air to the service line.
Go to the rear of the rig.
Open the emergency line shutoff valve at the rear of the last trailer. You should hear air escaping, showing the entire system is charged.
Close the emergency line valve.
Open the service line valve to check that service pressure goes through all the trailers.
How do you know if your converter dolly is
equipped with antilock brakes?
Converter dollies built on or after March 1, 1998, are required to have antilock brakes. These dollies will have a yellow lamp on the left side of the dolly.
