| 摘要 |
A pressure compensating flow control hydraulic circuit having a holding valve is disclosed. The pressure compensating flow control hydraulic circuit can perform the function of a holding valve so as to prevent the naturally lowering phenomenon of a working unit due to the leakage of a hydraulic fluid when the working unit is located in a neutral position, and can perform the function of a flow control valve when the working unit is operated. The pressure compensating flow control hydraulic circuit includes first and second hydraulic pumps; a boom cylinder for being supplied with a hydraulic fluid from the first hydraulic pump when a control valve of the boom cylinder is switched over; an arm cylinder for being supplied with the hydraulic fluid from the second hydraulic pump when a control valve is of the arm cylinder is switched over; a holding valve for preventing an arm from being naturally lowered due to a load pressure; an auxiliary spool for being switched over in response to a pilot signal applied from an outside to release a load of the arm cylinder; and a flow control valve for controlling a flow rate of the hydraulic fluid to drain from the small chamber of the arm cylinder to the hydraulic tank constantly when the auxiliary spool is switched over.
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