| 摘要 |
<p>PURPOSE:To reduce the loss of power by controlling the discharg rate of a variable pump to a minimum by using a system in which the pressure of drain when each operating valve is at neutral is taken out in dynamic pressure and NC valve is controlled by using its pilot pressure. CONSTITUTION:The discharge pressures of the first and second variable pumps 1 and 2 are supplied to turning valves 8 and 9, and when the turning valves 8 and 9 are at neutral, the discharge pressure of the first variable pump 1 is joined with that of the third variable pump 3 and the discharge pressure of the second variable pump 2 is joined with that of the fourth variable pump 4. Pressure detecctors 22 and 23 detect dynamic pressures, the spool of negative control valves 27, 28, 30, and 31 is pressed toward the left side, pressure oil supplied to servo mechanisms 1b-4b is drained, and the inclined angles of swash plates 1a-4a are controlled in such a way that the discharge amounts of the first the fourth variable pumps 1-4 are minimized.</p> |
