When the control lever is moved to “UP” position, the spool (1) is pulled out from the position control valve
body as shown in the figure.
The high-pressured oil delivered from P port flows through the oil passage of the spool (1) into the A chamber (a).
Since the spring behind the unload poppet (2) and the pressured oil entered to the A chamber (a) push and close the unload poppet (2).
At this condition, the pressured oil flows to the C port.
Since the poppet 1 (3) is opened by the pressured oil, the pressured oil flows through C port to the hydraulic cylinder, lifting a implement.
