| 摘要 |
PURPOSE:To improve the operating performance of an oil hydraulic unit during acceleration or deceleration by connecting an oil hydraulic motor and a passage connected to a pump with a check valve and also by shifting the forming time of an acceleration pressure control section and a brake pressure control section. CONSTITUTION:A passage 48 connected to both side ports of an oil hydraulic motor 51 through paassages 50, 50' and a spool 30 when the spool 30 is at a neutral position and a passage 45 connected to a pump 47 are connected to each other with a check valve 62. Next, an acceleration pressure control section 66' is formed with a notch section 63' formed on the recessed groove 44' side of a land 34' and a ring groove 38, and also a brake pressure control section 69 is formed with a notch section 64 formed on the recessed groove 49 side of a land 35 and a ring groove 40. When the spool 30 is moved to one direction from the neutral position, the brake pressure control section 69 is first formed, and after it has vanished the acceleration pressure control section 66' is formed. Thereby, the operability during acceleration or deceleration is improved and cavitation can be prevented from occurring. |
