HYDRAULIC HAMMERING DEVICE

摘要

A hydraulic hammering device for hammering a chisel by reciprocatively moving a hammering piston has a brake chamber, a stroke-regulating valve, and a holding mechanism. The brake chamber is turned to be a sealed-up chamber by the hammering piston when the piston moves in the hammering direction of the chisel by a predetermined distance beyond a regular hammering position. The stroke-regulating valve sends out a signal when a pressure in the brake chamber exceeds a predetermined value, which is done to shorten a stroke for a reduced hammering force. The holding mechanism holds the stroke-regulating valve at its switching position for predetermined time. The hydraulic hammering device also has a supplying mechanism. When the hammering piston is in the braking chamber at the time when hammering starts, the supplying mechanism supplies an operation fluid into the brake chamber to make the piston escape from the brake chamber.