Ppc Accumulator - Komatsu Galeo PC800-8 Shop Manual

10 Structure, function and maintenance standard

PPC accumulator

Function
• The accumulator is installed between the PPC
control pump and the PPC valve. Even if the en-
gine is stopped with the work equipment raised,
pilot oil pressure is sent to the main control valve
by the pressure of the nitrogen gas compressed
inside the accumulator, so it is possible to lower
the work equipment under its own weight.
Operation
• After the engine stops, when the PPC valve is at
neutral, chamber A inside the bladder is com-
pressed by the oil pressure in chamber B.
• If the PPC valve is operated, the oil pressure in
chamber B becomes less than 2.9 MPa {30 kg/
cm }, so the bladder expands under the pressure
2
of the nitrogen gas in chamber A. The oil enter-
ing chamber B is sent as the pilot pressure to ac-
tuate the main control valve.
PC800, 850-8
1. Gas plug
2. Shell
3. Poppet
4. Holder
5. Bladder
6. Oil port
Specifications
Type of gas
Gas volume
Max. actuating pressure: 3.1 MPa {32 kg/cm
Min. actuating pressure : 1.2 MPa {12 kg/cm
SEN00384-02
: Nitrogen gas
: 300 cc
}
2
}
2
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