Komatsu Galeo BR380JG-1E0 Shop Manual page 173

10 Structure, function and maintenance standard
2) When signal current is very small
(coil is energized)
When a very small signal current flows to coil
q
(5), coil (5) is energized, and a propulsion force
is generated on the left side of plunger (6).
Rod (4) pushes spool (2) to the left, and pres-
q
surized oil flows from port (P) to port (C).
Pressures on port (C) increases and the force
q
to act on surface (a) of spool (2) and the spring
load on spring (3) become larger than the pro-
pulsion force of plunger (6).
Spool (2) is pushed to the right, port (P) is shut
q
off from port (C).
Ports (C) and (T) are connected.
Spool (2) moves up and down so that the pro-
q
pulsion force of plunger (6) may be balance
with pressure of port (C) + spring load of spring
(3).
The circuit pressure between the EPC valve
q
and the control valve is controlled in proportion
to the size of the signal current.
BR380JG-1E0
3) When signal current is maximum
(coil is energized)
As the signal current flows to coil (5), coil (5) is
q
energized.
When this happens, the signal current is at its
q
maximum, so the propulsion force of plunger
(6) is also at its maximum.
Spool (2) is pushed to the left by rod (4).
q
The maximum volume of pressurized oil is
q
conducted from port (P) to port (C), increasing
the circuit pressure across EPC valve and the
control valve to the maximum level.
Since port (T) is closed, pressurized oil does
q
not flow to the hydraulic tank.
SEN01353-00
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