The fifth wheel is now in the lockset posi-
tion and is ready for uncoupling. As the
vehicle pulls away from the trailer the
kingpin forces the jaw to rotate, contacting
the lock. Continued rotation of the jaw
forces the lock to move outward, and
drops the upper rod back into the slot.
See
Fig. 17.9 View D. The wheel is now
ready for coupling.
6.3
Jost: Pull the retractable handle out, then
secure it in the open position with the
catch. See
Fig. 17.7.
7.
Release the vehicle parking brake, then drive
forward slowly, allowing the trailer to slide down
the fifth wheel and pick-up ramps.
Air-Actuated Uncoupling
An air-actuated kingpin release valve is optional with
all fifth wheels. See
Fig. 17.10.
NOTE: In the event of an air system failure, air-
actuated kingpins can be manually released fol-
lowing the instructions for manual unlocking.
WARNING
Once the kingpin release valve has been pulled
the kingpin lock is released. The vehicle MUST
NOT be driven with the trailer until the trailer has
been uncoupled and coupled again. Failure to do
so may result in separation of the trailer from the
tractor, possibly causing serious personal injury
or death.
Preparing the Trailer for Uncoupling
Before using the air valve to unlock a fifth wheel
kingpin, prepare the trailer as follows.
1.
Apply the vehicle and trailer parking brakes.
2.
Chock the rear trailer tires.
3.
Lower the trailer landing gear until the weight is
removed from the fifth wheel.
4.
Disconnect the tractor-to-trailer air lines and elec-
trical cable. Plug the air lines to prevent dirt or
foreign material from entering the lines.
Air-Activated Kingpin Unlock, Fontaine
and Holland Fifth Wheels
1.
Verify that both the yellow parking-brake and red
trailer-air supply knobs are out, the vehicle and
trailer parking brakes are set, and that the trailer
is prepared for uncoupling.
NOTE: If the vehicle parking brake is not set,
the air-actuated kingpin-release valve will not
activate.
09/10/2010 f311127
OK
OK
Fig. 17.8, Jost Release Handle Locked
Fifth Wheels
17.5
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