| 摘要 |
PURPOSE:To enable both the positive and the negative flow control by acting the output from a pilot spool mechanism to an oil passage change-over mechanism via a transmission lever having both an output part and opposing fulcrum parts and selectively supporting these fulcrum point parts. CONSTITUTION:When an external pilot pressure Pi varies, a pilot spool displaced. The displacement is transmitted to an operating member 25 from the output part 53c of a transmission lever 53 to change over an oil passage change- over mechanism 20. As a result, the servo piston 12 of a servo cylinder mechanism 10 is moved to change a swash plate 1 in angle of turn so that the displacement of a hydraulic pump P varies. When the displacement reaches to the level corresponding to the external pilot pressure Pi, the operating member 25 is returned by a feed-back lever 51 to move the oil passage change-over mechanism 20 to the neutral position. At this time according to the selection of the positive or negative fulcrum point 53e or 53d supported, the angle of turn of the swash plate 1 is increased or decreased. |
