New Holland CSX7000 Service Manual page 48

DISTRIBUTION SYSTEMS - PRIMARY HYDRAULIC POWER SYSTEM
Stack valve - Dynamic description
If all valves are in the "0" position, then:
The valves (13), (15), (17), (21) and (28), (Refer to Stack valve - Static description (A.10.A)) are closed, which
means that the oil can not flow through these valves.
The pressure raises at (7b), (27b), until the load sensing spool is pushed open against spring pressure (delta P= 3
bar) and the return pressure in the pilot line (7a), (27a). Now pump oil flows into the return line at standby pressure.
When activating the lateral float control spools (if installed), the hydraulic cylinder pressure (pump pressure measured
after the spool restriction) is present in the pilot line (7a), (27a) and closes the load sensing spool. The oil pressure is
available for the activated control spool(s).
When the pump pressure reaches the cylinder pressure (+ 3 bar), the load sensing spool is pushed open. The nec-
essary amount of oil will flow to the control spool at the needed pressure. Excess oil is dumped into the return line.
When activating valves without direct load sensing, (13), (15), (17) and (21), the pilot valve (42) is activated as well to
connect the pressure line with the load sensing line and closes the load sensing spool. The oil pressure is available
for the activated control spool(s).
When the pump pressure reaches the cylinder pressure (+ 3 bar), the load sensing spool is pushed open. The nec-
essary amount of oil will flow to the control spool at the needed pressure. Excess oil is dumped into the return line.
When the cylinder reaches end of stroke, the system pressure starts to raise. When the pilot pressure reaches 207
bar for the main stack valve ( 175 bar for the lateral float stack valve) the pressure relief valve is pushed open and
system pressure is limited to 210 bar (207 + 3 bar)
The load sensing lockout valve ensures that pilot pressure cannot escape into the return.
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