A hammer drill is provided including a housing, a motor mounted within the housing, and a hammer mechanism. The hammer mechanism includes a crank plate or a wobble plate driven by the motor, a con rod coupled to the crank plate or the wobble plate, a piston reciprocatingly driven by the con rod along a longitudinal axis, a ram and a beat piece. At least one of the wobble plate or the con rod is made of sintered steel.

The self-contained force magnifying tool disclosed herein includes a tool portion, a striker, at least a portion of which is disposed within the tool portion, and a spring, a least a portion of which is disposed within the tool portion. The spring attaches to both the tool portion and the striker. When the striker is pulled by a user, the spring stores mechanical energy. When the user releases the striker, the striker impacts on the tool portion transferring the mechanical energy stored in the spring into a driving force. The force is magnified by a tool disposed on the tool portion of the self-contained force magnifying hand tool and applied to a workpiece.

A mallet is described that has at least one cleft, in such a structure that the stress wave created during impact has longer travel way than the length of the mallet as measured along the impact line. This mallet induces longer-lasting and weaker stress wave(s) in the anvil as compared to a solid mallet having the same outer dimensions and more or less the same weight. The Cleft-Mallet increases the effectiveness of the strike, while decreasing the stresses in the anvil.

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 steel constituting a chisel according to the present invention includes: 0.40-0.45% by mass of carbon, 0.50-0.80% by mass of silicon, 1.00-1.30% by mass of manganese, 0.001-0.005% by mass of sulfur, 2.90-3.80% by mass of chromium, and 0.20-0.40% by mass of molybdenum, with a balance consisting of iron and an unavoidable impurity, the steel has an ideal critical diameter DI defined by Equation (1) of 600 or more:

DI=7.Math.(% C).sup.1/2.Math.(1+0.64.Math.% Si).Math.(1+4.1.Math.% Mn).Math.(1+2.83.Math.% P).Math.(10.62.Math.% S).Math.(1+2.33.Math.% Cr).Math.(1+3.14.Math.% Mo)(1).

A tool holder for a rotating and chiseling portable power tool is disclosed. A hollow spindle surrounds, coaxially with a working axis, a receiving space for receiving a tool. The hollow spindle has at least one cutout in the radial direction. An insert is inserted into the cutout in the radial direction. The insert has a rib that protrudes into the receiving space in the radial direction. A channel is arranged within the cutout and extends along the working axis. The channel is open into the receiving space and is bounded by the insert and an inner face of the cutout.