Combination Flashcards
What two things are important to prevent rollovers?
- keep the cargo as close to the ground as possible
* drive slowly around turns
What is the emergency aid line for?
It supplies air to the trailer air tanks and controls the emergency brakes on combination vehicles.
What is offtracking?
Offtracking is when the rear wheels follow a different path than the front wheels.
Which shut-off valves should be open and which closed?
The front trailers shut-off valves open and the rear closed.
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?
There should be no space!
Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply the trailer with the hand control trolley valve, if so equipped.
This is how you can test the trailer service brakes.
When you turn suddenly while pulling double trailers which trialled is most liked to turn over?
The rear trailer
TRUE or FALSE to drive you need to raise the landing gear only until it just lifts off the pavement.
FALSE
What describes 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
Where are the shut-off valves?
At the back of each trailer.
Why should you not use the trailer hand valve while driving?
It should not be used while driving because of the danger of making the trailer skid
The service line carries air which is controlled by:
- the foot brake or trailer hand brake
- the foot brake
- the trailer hand break
Why should goi not use the trailer hand brake to straighten out a jackknifing trailer?
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 straighten out.
TRUE or FLASE should you look into the back of the fifth wheel to see if is is locked onto the kingpin?
TRUE
Why should you use chocks when parking a trailer without spring brakes?
If the air supply in the trailer air tank had leaked away there will be no emergency brakes enabling the trailer wheels to turn freely
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. Close the emergency line valve. Open the service line valve to check that service pressure goes through all the trailers, then close the valve. If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailers and dollys are in the OPEN position.
This is how you test that air flows to all trailers.
Charge the trailer air brake system and check that the trailer rolls freely. Then stop and pull out the trailer air supply control valve. Pull gently on the trailer with the tractor to check that the trailer emergency brakes are on.
This is how you can test the trailer emergency brakes
Charge the trailer air brake system and push the air supply knob in. Shut the engine off. Step on and off the brake pedal several times to reduce the air pressure in the tanks. The trailer air supply control should pop out when the air pressure falls into the pressure range specified by the manufacturer.
This is how you can test the tractor protection valve