Hitachi ZW180 Technical Manual page 134

Front Attachment Operation Circuit
•
Pressure oil from the pilot pump flows to the
charging block, comes out of port PP of the
charging block and is supplied to each pilot valve
through the pilot shut-off valve.
•
The priority valve of the charging block supplies
pressure oil preferentially to the service brake
circuit when pressure in the service brake
accumulators is lowered. (Refer to Charging
Block Circuit.)
•
The pilot shut-off valve is a manually operated
type, and is installed in order to prevent accidents
due to wrong operation by stopping suppy of
pressure oil to the pilot valve when it is closed.
•
By controlling each pilot valve, pressure oil from
the pilot pump shifts the control valve spools.
•
At both ends of the spool for the lift arm cylinders
of the control valve, the slow-return valves are
installed in order to moderate sudden movement
of the spool.
SYSTEM / Hydraulic System
T2-3-18