HYDRAULIC HAMMERING DEVICE

摘要

Provided is a hydraulic hammering device having improved hammering efficiency and of low cost. A piston (200) has a valve switching groove (205) between large-diameter sections thereof. A cylinder (100) has three control ports (112, 113, 114) at positions corresponding to the valve switching groove (205) . A switching valve mechanism (210) has a valve presser for always pressing a valve (300) in one direction and also has a valve controller for moving, when supplying pressurized oil, the valve (300) in the opposite direction against the pressing force of the valve presser. A valve control port (114) communicates with the valve controller so as to supply the pressurized oil to the valve controller and is separated from a piston front chamber (110) and a piston rear chamber (111). Only either a piston retraction control port (113) or a piston advance control port (112) communicates with the valve control port (114) depending on advance or retraction of the valve switching groove (205).