| 摘要 |
<p>PURPOSE:To make it possible to perform a pressure liquid combining operation and an actuator accelerating operation by a method wherein the opening and closing of each of supply pipes of three pumps and the opening and closing of each of connecting pipes connecting the supply pipes are controlled in various ways by three logic valves so that pressure liquids from the pumps join together. CONSTITUTION:In case where a signal port (c) of a second logic valve 8 is closed and signal ports (c) of first and third logic valves 7 and 9 are opened, the pressure oil from a first pump 1 flows from an outlet (b) of the first logic valve 7 to a tank 10 while the pressure oils in second and third pumps 11 and 20 flow from an outlet (b) of the third logic valve 9 through the supply pipes 12 and 21, respectively. In this case, when a changeover valve 13 for effecting left side running is operated, the pressure oil from the second pump 11 is interrupted but the pressure oil from the third pump 20 flows into an arm changeover valve 14 and a second boom changeover valve 15 to thereby perform the combining operation of the pressure oils. Further, when an acceleration changeover valve 26 is operated, the pressure oil from the third pump 20 gathers in the supply pipes 2 and 12 so that the actuator is accelerated by a rate corresponding to a tributary flow of the pressure oil, due to the actions of the logic valves 7, 8 and 9.</p> |
