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COMPONENTS CX130
CASE TRAINING CENTER
AUGUST 2000
Cushionning operation
In Soft mode, the solenoid switch is off and the pilot pressure doesn't come from port "S".
Thus, the cushion spool inside the cushion valve is still set as original position and has a restriction of pressure by
orifice inside the spool rooms.
The spool has 3 rooms, for instance, upper, middle and lower and due to no pressure from port "S", the middle
and lower rooms are to use.
The pressurized oil flow from port "D" is going to middle room first, however, due to the orifice restriction, the oil
flow is separated and such separated oil flow pushes up the spool to lower room, which has still another orifice.
Before going to the port "B" to the control valve, the oil flow is also separated and pushes back the spool to mid-
dle.
These room changes inside the cushion spool and orifice restriction differences are changing the tank pressure
and such mechanism makes arm spool in the control valve returning neutral so slowly; spool damper effect.
That is how the cushion occurs and reduces the shock when arm opening stops.
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