A machine tool includes a tool holder and a pneumatic striking mechanism that includes, on a working axis, an exciter piston, a beater, and a pneumatic chamber disposed between the exciter piston and the beater. The exciter piston is drivable by the motor and includes a pot-shaped base body, a seal ring, and a tube-shaped cladding body. The pot-shaped base body has a lateral wall enclosing the working axis and a collar which protrudes in a radial direction. The tube-shaped cladding body is disposed on the pot-shaped base body surrounding the lateral wall. A groove is defined between the collar and the tube-shaped cladding body and the seal ring is disposed in the groove.

An impact mechanism device for a hand power tool comprises at least one impact mechanism including at least one driven cylinder and at least one piston driven in an axial direction by the at least one driven cylinder via a cam mechanism, and at least one planetary gearing configured to drive the at least one driven cylinder and the at least one piston. The at least one piston is positioned at least partially inside the at least one driven cylinder.

The sealing device includes an inner sealing ring including an annular inner sealing portion provided with a sealing lip intended to cooperate in a sealed manner with the outer surface of a striking piston of a hydraulic percussion apparatus, and an outer sealing element mounted around the inner sealing portion and intended to bear in a sealed manner at the bottom of an annular housing arranged on a guide body of the hydraulic percussion apparatus. The inner sealing ring further includes an annular protective portion axially shifted relative to the inner sealing portion and internally delimited by at least one converging protective surface, annular and converging towards the sealing lip, and an annular groove opening into the inside the inner sealing ring, the annular groove being disposed between the sealing lip and the converging protective surface.

A hammer drill comprising: a body; a motor mounted within the body; a transmission housing mounted within the body, a transmission mechanism mounted within the transmission housing which is capable of rotatably driving and/or repetitively striking a cutting tool held by the hammer drill in response to rotation of an output shaft of the motor; wherein the transmission housing comprises a pair of housing portions adapted to engage each other to support the component parts of the transmission mechanism within the transmission housing; wherein the first housing portion is made from metal and the second housing portion is made from a plastic material, each of the components of the transmission mechanism being supported jointly be the first and second housing portions.

An electropneumatic impact mechanism for an electric hand-held power tool, in particular a hammer drill and/or chipping hammer, wherein the impact mechanism has a transmission housing, a guide tube arranged at least partially in the transmission housing, an exciter piston that is movable in the axial direction in the guide tube, a connecting rod coupled to the exciter piston, and an eccentric wheel which is coupled to the connecting rod on one side and is mounted so as to be rotatable with respect to the transmission housing on the other side, wherein the impact mechanism has a bearing body on which the eccentric wheel is mounted rotatably by means of a pair of plain bearings.

Composite gearwheel for an electropneumatic hammer drill, wherein the composite gearwheel has a basic body, consisting of a first material, and an encircling toothing, and wherein the encircling toothing is formed, along a first circular arc, by a toothed body of the composite gearwheel, and is formed, along the remaining second circular arc, by the basic body itself, wherein the toothed body consists of a second material that is different than the first material.

A hand-held power tool has a tool socket 2 to hold a tool on a working axis 11. A pneumatic striking mechanism 6 has an exciter piston 13 that is forced to move periodically along the working axis 11 by a motor 5 and it also has a striker 14 that is coupled to the exciter piston 13 via a pneumatic chamber 18. The exciter piston 13 has a cylindrical main body 21 made of a polymer. One or more rings 24 containing copper surround the main body 21. The rings 24 protrude from the main body 21 in the radial direction.