To supply only necessary level of oil to an optional device even in a case of complex operations in which both an operational device and an optional device are driven at the same time.
A hydraulic circuit for full equipment optional is equipped with a variable capacity type hydraulic pump, an optional device, a main control valve, the first electromagnetic proportioning pressure reducing valve, and a remote control valve. Further, the circuit has a poppet valve to be fitted to be openable and closable in a supply side channel of a spool for optional equipment; the second electromagnetic proportionally pressure reducing valve to control a supplied flow rate to the optional and the operational devices, and to control a boom unification spool by outputing the secondary pressure corresponding to an electric signal which is input from the controller; and the first spool which is set in a downstream of the poppet valve to reduce its opening area, and has a function of flow rate control valve in pressure compensation profile when a pressure difference in the front and the rear points of the boom unification spool is bigger than the designated value.
| JP2003049803A | 2003-02-21 | |||
| JP2001012403A | 2001-01-16 | |||
| JPH08219121A | 1996-08-27 | |||
| JP2003194006A | 2003-07-09 |
| WO1993005301A1 | 1993-03-18 | |||
| WO1994010456A1 | 1994-05-11 |
Hideo Shimizu
Yuichi Takagi
Yoshinao Nakano
Kazuki Hidaka
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