55 - 6
Section E
Hydraulics
9803/6400
Section E
55 - 6
Issue 1
Cushion Valves
Operation (continued)
During Dipper Closed and Stopping
a. When the pilot pressure from the remote control
valve stops, the reverse notch spool returns to
neutral.
b. Also, the cushion spool returns to neutral and the
pilot oil returning from the control valve passes
through the throttle a and b. Because the cushion
spool moves to the left side due to the differential
pressure before and after the throttle, the pilot return
oil is throttled by throttle a.
c. Due to this throttling effect, the spool of the main
control valve slowly returns to neutral.
Normal State
When the cushion switch is switched to the normal position,
the solenoid valve is selected and the pilot pressure (40
kgf/cm
2
) of the gear pump enters the S port of the cushion
valve.
All the cushion spools (Boom, dipper - total of 4) are selected
forcibly to the inner side.
Because the cushion spool is forcibly pushed down, the pilot
pressure does not pass through the throttle of the cushion
spool during the dipper closing or stopping operations but
passes through the cushion valve inside.
The hot oil from R port returns to the hydraulic oil tank from
the T port when the lever is at neutral.
When the lever is being moved, it flows to the remote control
valve.
To Next Page
Loading...
Need help?
General
