New Holland T8010 Manual page 848

Extend
When the remote hydraulic control lever is moved to
the extend position, the main valve spool is shifted to
the left a fixed distance by the proportional solenoid
pressure supply. The position of the main valve spool
determines the flow rate to the extend port.
As PFC pump supply oil flows past the pressure
compensated flow control spool, there is a pressure
drop, to an intermediate pressure. The intermediate
pressure is always equal to the pressure required by
the load, plus 100 PSI. The added 100 PSI is needed
to balance the spring force on the right hand side of
the pressure compensated flow control spool.
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13. EXTEND PORT
14. RETRACT PORT
15. LOAD CHECK PLUNGER
16. MAIN VALVE SPOOL
17. PRESSURE COMPENSATED FLOW CONTROL SPOOL
18. PROPORTIONAL SOLENOID (EXTEND)
19. PROPORTIONAL SOLENOID (RETRACT)
20. PFC PUMP SUPPLY
Section 35 - Hydraulic Systems, 3PT - Chapter 5
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The main valve spool can now direct flow from the
intermediate pressure area to the work pressure area
and on to the remote valve coupler. As oil flows
across the main valve spool there is always a 100
PSI pressure drop. This constant pressure drop
results in a constant flow across the main spool out
to the remote coupler. The constant pressure drop is
maintained through a balance of inter mediate
pressure on the left hand side of the pressure
compensated flow control spool and work pressure
plus the spring force on the right hand side of the
spool.
At the same time the main valve spool first shifts,
work pressure is also directed to the signal checks.
The work port pressure can open the signal check
valve and signal the pump compensator to increase
PFC pump flow. The work pressure is also directed to
the relief signal check to limit the remote sections
maximum pressure.
The flow exiting the extend port is in a free flow
condition, the load check only works in the opposite
direction. Return oil from the lower coupler is directed
into the retract port, past the spool and on to the inlet
side of the filter base.
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21. REGULATED PRESSURE SUPPLY
22. BACK TO TANK
23. SIGNAL LINE TO COMPENSATOR
24. TO REMOTE SIGNAL RELIEF VALVE
25. PILOT DRAIN
26. SIGNAL CHECK TO PUMP COMPENSATOR
27. SIGNAL CHECK PILOT RELIEF
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