New Holland WorkMaster 50 Service Manual page 464

Hydraulic systems - Main control valve
B. Lifting phase
During this phase, the control valve supplies the oil under pressure to the cylinder (9) and it consequently lifts the
arms.
The control spool (1) is in such a position to connect the chamber (5) of the differential valve (2) with the oil coming
from the pump through annular duct (8) and holes (12) and (13) making in this way the valve itself to close.
The oil from the pump finding the differential valve (2) closed goes to cylinder, pass the hole (14) opens the check
valve (3) enters in the annular duct (11) and enters the chamber (9).
The lifting speed depends on the pump RPM.
In this phase the maximum lifting pressure is controlled by the safety valve (15) that is connected to annular duct (8)
through hole (14) and then to the oil inlet.
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