Pack Circuit Dump Valve - Wittke STARLIGHT Maintenance Manual

114 Hydraulic System
4. Raise and lower the arms while running the engine at idle speed and again while running the
engine at 1500 RPM.
N : The arms should slow down when they are approximately 18 inches (45.72 cm) away from
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being lowered and gently come to rest at the bottom of their travel.
5. If the arms reach the bottom of their travel with jarring impact or the arms stop before being fully
lowered:
Loosen the retaining bolt and tap the cam in the required direction.
5 a.
Tighten the retaining bolt of the cam and repeat Step 4.
5 b.
6.
Grab a container or carry can with the forks and repeat Steps 4 and 5.
: Some containers may not allow the arms to go down low enough to proceed with the correct
N
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adjustment.
7.
Remove the container from the forks and repeat Steps 5 and 6 until the arms properly decelerate
with and without a container on the forks.
8.
Tighten the locking setscrew.

Pack Circuit Dump Valve

The pilot-operated check valve (dump valve) is fitted into the pack hydraulic circuit for the purpose
of reducing power which is required for the packer to return to its "home" position.
Figure 7-35 Dump valve (shown on unit with front-mounted main valve)
Pressure in the pilot line during the return stroke opens the dump valve and allows approximately
50 percent of the oil exiting the cylinders to go directly to the hydraulic tank. The dump valve is non-
adjustable.
N : Signs of pack circuit dump valve failure include: poor payloads, slow cycle times and low
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pressure readings during the pack cycle.