| 摘要 |
PURPOSE:To prevent a circuit from heating due to the operation of a relief valve and save energy by automatically minimizing the discharge of a variable delivery pump through the operation of a cutoff control system when the discharge pressure of said variable delivery pump exceeds a set pressure determined by said control system. CONSTITUTION:The main elements of a cutoff control system (a) are a spool 39 whose outer end is applied to a pressure introducing passage 35, a spring holder 40, and a No.3 spring 41. When the discharge pressure of a variable pump 34 exceeds a prescribed pressure determined by the No.3 spring 41, the spool 39 is moved against the spring 41. As its land 44 passes through a pilot passage 45, a pressure-introducing passage 33 is connected to the pilot passage 45. Accordingly, a high pressure oil from a pump 1 flows into a pilot chamber 36 allowing a piston 18 to move further toward the left on the figure and minimizes the discharge of the pump 1 automatically, thereby preventing the circuit from heating due to the operation of a relief valve. |
