| 摘要 |
PURPOSE:To operate a working equipment at a vary low rate so as to execute a work of high accuracy by providing a means so as to switch a load sensing valve to a direction where a communicating area is rendered small when engine speed is high, so as to make the capacity larger than that based on the difference between discharge pressure and load pressure. CONSTITUTION:A load sensing valve 5 controls a communicating area of a pump discharge route 1a and a large-sized piston pressure cell 3a based on the difference in thrust between a discharge pressure P1 and load pressure PLS plus oil pressure of a pressure oil generating source 11, namely an auxiliary pressure part 10, and a discharge flow of a variable capacity pump 1 per rotation is so controlled as to stabilize the difference. The pressure oil generating source 11 generates pressure oil according to a detection signal of an engine speed sensor 12 in an engine 9. When the engine 9 is rotated at high speed, pressure oil of the pressure oil generating source 11 is increased, while the pressure of the large sized piston pressure cell 3a is decreased. A capacity adjusting member 2 thus works to a direction of large capacity, whereby discharge flow per rotation is increased so as to increase the discharge flow per hour. |
