| 摘要 |
PURPOSE:To omit a counter balance valve by inserting a plunger slidably into both spool ends in a changeover valve and acting a spring to the outer end of the plunger to connect a pressure chamber located at the side opposite to the spring to a pump. CONSTITUTION:A spool 23 both ends of which face pilot chambers 36, 37 is provided in a changeover valve V installed between a pump P and a fluid motor m. Plungers 41, 42 are inserted slidably into both ends of the spool 23 of the changeover valve V, meanwhile, springs 50, 51 located at the other ends of this plunger are put in action. Pressure chambers 43, 44 located at the side opposite to the springs 50, 51 are connected to the pump P. When a counter load acts on a motor for running, a delivery pressure of the pump P is dropped in a moment and plungers 41, 42 are moved by the action of the springs 50, 51 and the pilot chambers 36, 37 located at the spool 23 ends are connected to a tank.
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