10.
Apply the tractor parking brake, then perform a
physical check for positive kingpin lockup, and
that there is no gap between the trailer and the
fifth wheel. See
Fig. 20.5.
11.
Ensure that the release handle is in the locked
position adjacent to the casting. See
Fig. 20.7.
12.
Release the tractor parking brakes and test for
kingpin lockup by slowly moving the tractor for-
ward, pulling on the trailer against the chocks.
Fifth Wheel Uncoupling
Manual Uncoupling
1.
Apply the tractor and trailer parking brakes.
2.
Chock the trailer rear wheels.
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 control handle to the unlocked posi-
tion. See Fig. 20.1.
6.2
Holland: In the locked position the safety
indicator swings freely over the operating
rod. See
Fig. 20.8, View A.
To unlock the mechanism, manually rotate
the safety indicator toward the rear of the
fifth wheel. See
Fig. 20.8, View B.
Pull the operating rod out. When the
upper operating rod shoulder is outside
the slot, raise the handle and place the
shoulder of the upper rod against the plate
casting, above the slot. See
Fig. 20.8,
View C.
The fifth wheel is now in the lockset posi-
tion and is ready for uncoupling. As the
tractor pulls away from the trailer the king-
pin 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. 20.8
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. 20.6.
7.
Release the tractor parking brake then drive out
slowly, allowing the trailer to slide down the fifth
wheel and pick-up ramps.
f31112704/28/2017
OK
OK
Fig. 20.7, Jost Release Handle Locked
Fifth Wheels
20.4
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