Loader Valve - Variable Flow Operation - jcb 214e Service Manual

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Section E
7 - 1
Loader Valve - Variable Flow
Operation
The loader valve is mounted on the chassis frame, right
hand side (when viewed from rear).
It is a stack type, directional control valve that is configured
for closed centre operation. The valve block comprises two
or three service valve sections and a priority steer inlet
section.
When operated, the designated valve section controls the
volume and direction of oil by way of service ports A or B. A
constant flow is maintained regardless of changing load
pressures.
While the spools are in neutral position, the primary shuttles
and secondary shuttles are vented to tank. When a spool is
operated, the load pressure sensed at the work port is
directed via the primary and secondary shuttles to the
hydraulic pump, where the pump subsequently 'swashes' to
meet this load sense demand.
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9803/3280
Hydraulics
Circuit Descriptions
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Component Key:
1 Auxiliary (optional) spool
2 Shovel spool
3 Arms lift spool
4 Pump inlet
5 Tank port
6 Load sense port (from valve blocks)
7 Priority load sense port (from steer unit)
8 Priority work port (to steer unit)
9 Load sense carry over port (to backhoe valve)
10 Service ports
11 Auxiliary relief valve (rods side)
12 Auxiliary relief valve (head side)
13 Priority relief valve †
† Note: Steer circuit pressure is controlled by a relief valve
housed in the hydraulic steer unit (refer to Section H
Steering). The priority relief valve housed in the loader valve
must be set at 2500 lb/in
interfere with the operation of the relief valve housed in the
hydraulic steer unit.
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Section E
7 - 1
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