Hydraulic striking mechanism

Abstract

The invention relates to a hydraulic striking mechanism including a cylinder, a percussion piston guided therein and a piston return device which is supported on the percussion piston and is displaceable independently thereof and can be connected on its side facing the percussion piston tip alternatingly to a pressure source or a pressure-free return conduit. The piston return device is configured as an annular piston which is freely displaceable along the percussion piston and the cylinder and forms therewith a piston chamber. The percussion piston has an abutment face at its end remote from the percussion piston tip which cooperates with the annular piston for moving percussion piston in the return stoke direction. The percussion piston, together with the cylinder, defines an oil chamber which axially follows the piston chamber in a spaced relationship. The percussion piston is provided with a cylindrical shoulder within the oil chamber which determines its end position during the return stroke. The piston chamber and the oil chamber are connected with a control unit by means of which, when the percussion piston shoulder approaches the rear face of the oil chamber, the oil chamber can be connected to the return conduit and by way of which, when the annular piston approaches an annular face on the cylinder, the piston chamber can be connected with the pressure source.