A prior art powered wrist pin knocker is imported with a new plunger that prevents wobbling. The new plunger responds to a return vacuum pressure. The improved plunger is symmetrical along a longitudinal axis. New embodiments include a new side mount valve head to reduce length, a remote air controller and a variable length cylinder for the cannon. The new valve head is a simplified valve head assembly that adapts to an end of the cannon mount or a side mount or a remote mount. Another embodiment provides a stand for a surface mount application. This embodiment can have an extended piston for loosening tail bearings down a long channel. A manual return embodiment can use a rod to manually return the plunger to the proximal end for another firing cycle.

A piston for a hydraulic hammer of a work machine is disclosed. The piston comprises a first portion having a first diameter, a second portion having a second diameter larger than the first diameter, the second portion having a plurality of grooves, and a third portion having a third diameter less than the second diameter.

A power tool is disclosed. The power tool has a pneumatic percussion mechanism with a percussion element guided on a working axis and a percussion surface pointing in a percussion direction, an exciter piston driven by a motor, and a pneumatic chamber formed between the exciter piston and the percussion element. The percussion element has a first partial body forming the percussion surface, a second partial body, and a spring element. The first partial body is moveable along the working axis relative to the second partial body. The second partial body has an abutment surface pointing in the percussion direction. The first partial body has an impact surface opposite the abutment surface. The spring element drives the first partial body relative to the second partial body in the percussion direction into a starting position in which the abutment surface is separated from the impact surface by a gap.

A portable power tool has an exciter piston guided along a movement axis in a guide tube and a striker coupled to the exciter piston. A connecting rod is fastened to a piston pin in the exciter piston and to an electric motor. A bearing for supporting the piston pin is formed by a piston head of the exciter piston and a closure plate inserted into the exciter piston. A rotary closure is formed by a groove, extending in a direction of rotation about the movement axis, in the piston wall and by a radially protruding fin on the closure plate. A detent for locking the fin counter to the direction of rotation is pivotable in the radial direction between a locking position and a releasing position. The detent is deflected beyond the external dimensions of the piston wall in the radial direction in the releasing position.

A piston for a hydraulic hammer assembly is provided. The piston may include an elongate member extending from a distal end to a proximal end and having a first outer diameter, a flange disposed on the elongate member and having a second outer diameter greater than the first outer diameter, and a non-ferrous shoe radially disposed on the flange.

A prior art powered wrist pin knocker is imported with a new plunger that prevents wobbling. The new plunger responds to a return vacuum pressure. The improved plunger is symmetrical along a longitudinal axis. New embodiments include a new side mount valve head to reduce length, a remote air controller and a variable length cylinder for the cannon. The new valve head is a simplified valve head assembly that adapts to an end of the cannon mount or a side mount or a remote mount. Another embodiment provides a stand for a surface mount application. This embodiment can have an extended piston for loosening tail bearings down a long channel. A manual return embodiment can use a rod to manually return the plunger to the proximal end for another firing cycle.

A hand-held power tool is disclosed. The tool has a tool receptacle for holding a chiseling tool. A pneumatic percussion mechanism of the hand-held power tool includes a striker, an exciter and a guide tube. The striker is designed to apply impacts in the impact direction to the tool. The exciter is motor-driven. The striker is coupled by an air spring to the reciprocating movement of the exciter. The striker abutting the guide tube is guided along a working axis. During a movement between an impact position and the exciter, the striker is guided with a constant guide length on the guide tube and if the impact position is exceeded in the impact direction, the guide length is reduced. The hand-held power tool is equipped with an inclined guide, which inclines the striker relative to the working axis when the impact position is exceeded.

A circular cylindrical striker member 2 for a drilling machine adapted to transfer kinetic energy to an impulse receiving member 4. The striker member has a diameter d.sub.max, and includes a side surface 12 and an impulse surface (6). The striker member is adapted to transfer the kinetic energy to the impulse receiving member by a ring shaped active surface of the impulse surface, wherein the ring shaped active surface is concentric with regard to the cross section of the striker member, has a diameter d.sub.a, where d.sub.a<d.sub.max, and has a width w.sub.a that during the contact moment with the impulse receiving part is less than 0.2 d.sub.max.

An anvil configured to be impacted by a hammer in an impact wrench. The anvil defines a rotational axis. The anvil includes an anvil lug having a driven surface engageable with the hammer. The driven surface includes an involute profile. The involute profile is formed by a base cylinder defining a central axis. The central axis is offset from the rotational axis of the anvil.

A hammer mechanism having at least one impact-generation unit and a clamping chuck drive shaft is provided. The impact-generation unit includes a spur-gear transmission stage for translating a rotational speed of the clamping chuck drive shaft into a higher rotational speed for impact generation.