| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control apparatus enabling to prevent failure due to hunting, to elevate operating performance of a hydraulic control valve, and to improve operation efficiency through effectively conducting the bleed off. SOLUTION: There are provided: a variable capacity pump 7; a first change over valve group A including at least one change over valve connected with a first delivery line 12A branched from a delivery line 12 of the variable capacity pump and arranged to have load sensing function; a second change over valve group B connected with a second delivery line 12B branched from the delivery line 12; an open and close motion valve 136 which constitutes a pressure compensation flow control means connected through the second delivery line and the second change over valve group; and a compensation valve 138 connected to the downstream of the open and close motion valve. A passage 148 for bleed off is formed in the compensation valve. The bleed off is selectively conducted in accordance with a state of operation of a hydraulic circuit, in such a way that in case of relatively small demand for the flow rate in the hydraulic circuit, the bleed off is conducted so as to suppress the hunting, and in case that demand for the flow rate increases, the bleed off is not conducted. COPYRIGHT: (C)2006,JPO&NCIPI
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