Operation - Hitachi ZW180 Technical Manual

OPERATION

At Neutral (Pusher Stroke: Between A and B)
1. At the neutral position of the control lever, spool
(7) completely blocks pressure oil of port P. As the
outlet port is connected to port T through the
notch part of spool (7), pressure at the output port
is equal to pressure in the hydraulic oil tank.
2. When the control lever is moved slightly, lever (1)
is tilted, and push rod (2) and pusher (3) are
pushed in. Pusher (3) and spring guide (4) remain
mutually connected, and move downward while
compressing return spring (6).
3. At this time, spool (7) is pushed by balance spring
(5) and moves downward until the clearance in
part A becomes zero.
4. During this movement, the output port remains
connected with port T and pressure oil is not
supplied to the output port.
NOTE: The lever stroke during the period when
clearance (A) becomes zero is play of the
control lever.
COMPONENT OPERATION / Pilot Valve
Pilot
Pressure
A
T3-6-2
E F
D
C
Pusher Stroke
B
Output Diagram
T505-02-07-006