9803/3280
Issue 1
6 - 8
6 - 8
Circuit Descriptions
Section E
Section E
Loader Valve
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
34
Lift Ram
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.