10.
Apply the tractor parking brake, then perform a
physical check for positive kingpin lock, and that
there is no gap between the trailer and the fifth
wheel. See
Fig. 17.4.
11.
Ensure that the release handle is in the locked
position adjacent to the casting. See
Fig. 17.6.
12.
Release the tractor parking brakes and test for
kingpin lock by slowly moving the tractor forward,
pulling on the trailer against the chocks.
Fifth Wheel Uncoupling
Manual Uncoupling
1.
Apply the tractor and trailer parking brakes.
2.
Chock the trailer tires.
3.
Lower the trailer landing gear until the weight is
removed from the fifth wheel.
4.
Disconnect the tractor-to-trailer air system lines
and electrical cable. Plug the air lines to prevent
dirt or foreign material from entering the lines.
5.
Verify that both the yellow parking-brake and red
trailer-air-supply knobs are out, the tractor and
trailer parking brakes are set, and that the trailer
is prepared for uncoupling.
6.
Release the kingpin locking mechanism following
the instructions for each manufacturer below.
6.1
Fontaine: Lift the safety latch and pull the
lock release handle to the unlocked posi-
tion.
6.2
Holland: In the locked position the safety
indicator swings freely over the release
handle.
Pull the release handle out. When the
upper release handle shoulder is outside
the slot, raise the handle and place the
shoulder of the upper rod against the plate
casting, above the slot.
The fifth wheel is now in the lock position
and is ready for uncoupling. As the tractor
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. The wheel is
now ready for coupling.
6.3
Jost: Pull the retractable release handle
out, then secure it in the open position
with the catch. See
Fig. 17.5.
7.
Release the tractor parking brake then drive out
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
any fifth wheel. See Fig. 17.7.
05/29/2012 f311127a
Fig. 17.6, Jost Release Handle Locked
10/26/2010 f611102
Fig. 17.7, Air-Actuated Kingpin Release Valve
Fifth Wheels
17.4
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