JPS57179407A - Fluid actuator - Google Patents

Abstract

PURPOSE:To achieve an actuator suitable for a pile hammer employing a fluid actuator which performs the actuator function in accordance to the resonance of the pile for the inherent frequency of the soil by providing a relief valve between two flow paths conducting both chambers of the actuator as the bypass circuit. CONSTITUTION:The pressurized oil from a pump 1 will enter through a rotary direction exchange valve 2 and through the flow paths 16, 17 alternatively into the liquid chambers 12, 13 of a cylinder to vibrate a piston 65 thus to drive a pile 11. When the pile 11 will resonate with the inherent frequency of the soil, the amount of oil to be fed from the pump 1 to the liquid chambers 12 or 13 will be insufficient but the differential pressure across the check valve 18 or 19 will function the on-off valve 29 or 35 while to open the relief valve 22 or 23 thus to conduct between the liquid chamber 12 and 13, thereby the amount of oil in both chambers are regulated to perform the driving where the resonance is utilized positively.