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Section E
6 - 8
Loader Valve
Arms Lower
When a spool is selected as shown at 3C, the central land of
the spool C blocks the neutral circuit. Oil from the pump,
entering at 1A, is diverted into the parallel gallery B, opens
the load hold check valve 3J, and flows around the waisted
section of the spool D and out to the rod side of lift rams 33
and 34.
The lower land of the selected spool E blocks the flow from
the parallel gallery to the head side port and oil returning
from the rams is diverted into the exhaust gallery.
Float
The float facility is provided to allow the arms to move up
and down so that the shovel can follow the surface contours
as the machine is driven over uneven ground.
This is achieved by moving the lift spool 3C down beyond
'arms lower' into the 'float' detent, when the feed from the
parallel gallery to the service ports is blocked and the neutral
circuit is re-opened. Both service ports are connected to
exhaust via the spool waists A.
Oil can then be displaced from either end of the lift rams 33
and 34 into the exhaust gallery, allowing the rams to open
and close as required.
9803/3280
Hydraulics
Circuit Descriptions
Purchased from www.WorkshopManuals.co.uk
Component Key:
A
Spool Waists
B
Parallel Gallery
C
Central Land
D
Spool Waist
E
Lower Waist
1A Pump Inlet
3C Lift Ram Spool
3J
Load Hold Check Valve
33
Lift Ram
Lift Ram
34
Section E
6 - 8
Issue 1
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