Abstract: A motor driven hammer having a housing, a motor having a motor shaft and being arranged in the housing, a hammer mechanism including a cylinder in which a ram is arranged the ram being slidable along a longitudinal axis (L) of the cylinder, and a tool holder which may support a tool bit so that the tool bit is aligned with the longitudinal axis of the cylinder, wherein the motor is coupled with the hammer mechanism, so that rotation of the motor shaft results in a reciprocating movement of the ram within the cylinder, the ram applying impacts on a tool bit supported by the tool holder during the reciprocating movement. Further, the ram is made of a paramagnetic or ferromagnetic material or comprises a permanent magnet and a coil is arranged within the housing adjacent to the cylinder so that the coil applies a force in the direction of the longitudinal axis on the ram if a current is applied to the coil.

Abstract: A method of assembling a hand held electrically powered drilling and/or hammering tool having a tool housing and a drilling and/or hammering spindle mounted within the housing. The spindle has a forward end at which a tool or bit may be mounted. The method of assembly includes the steps of making a motor sub-assembly including a motor and a radial fan, the fan has a plurality of blades located on one side of the fan and non-rotatably mounting the fan on an end of the armature shaft of the motor at a first end of the motor with the blades facing away from the armature of the motor. The method further including balancing the motor sub-assembly, and mounting the sub-assembly within the housing, with the longitudinal axis of the motor armature shaft at an angle, preferably perpendicular to the longitudinal axis of the spindle and with the first end of the motor closest to the spindle axis.

Abstract: A powered hammer is described comprising a housing, a tool holder mounted on the housing, a percussion mechanism arranged within the housing which mechanism includes a ram reciprocating in a longitudinal direction and being adapted to apply impacts on a tool bit supported in the tool holder, a dampening mass which is slidably mounted in the longitudinal direction within the housing, wherein the dampening mass is biased towards a neutral position by a biasing element and wherein the dampening mass may be deflected from the neutral position against the biasing force of the biasing element. The dampening mass is formed of a ferromagnetic or paramagnetic material or comprises a permanent magnet and a solenoid is arranged within housing adjacent to the dampening mass such that the solenoid applies a force in the longitudinal direction on the dampening mass when being in the neutral position if a current is flowing through the solenoid.

Abstract: A motor driven hammer is described comprising a housing (3), a motor (9) having a motor shaft (11) and being arranged in the housing (3), a hammer mechanism including a cylinder (17) in which a ram (23) is arranged the ram being slidable along a longitudinal axis (L) of the cylinder (17), and a tool holder (15) which may support a tool bit so that the tool bit is aligned with the longitudinal axis (L) of the cylinder (17), wherein the motor (9) is coupled with the hammer mechanism, so that rotation of the motor shaft (11) results in a reciprocating movement of the ram (23) within the cylinder (17), the ram (23) applying impacts on a tool bit supported by the tool holder (15) during the reciprocating movement.

Abstract: A powered hammer is described comprising a housing, a tool holder mounted on the housing, a percussion mechanism arranged within the housing which mechanism includes a ram reciprocating in a longitudinal direction and being adapted to apply impacts on a tool bit supported in the tool holder, a dampening mass which is slidably mounted in the longitudinal direction within the housing, wherein the dampening mass is biased towards a neutral position by a biasing element and wherein the dampening mass may be deflected from the neutral position against the biasing force of the biasing element. The dampening mass is formed of a ferromagnetic or paramagnetic material or comprises a permanent magnet and a solenoid is arranged within housing adjacent to the dampening mass such that the solenoid applies a force in the longitudinal direction on the dampening mass when being in the neutral position if a current is flowing through the solenoid.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: A method of assembling a hand held electrically powered drilling and/or hammering tool having a tool housing and a drilling and/or hammering spindle mounted within the housing, which spindle has a forward end at which a tool or bit may be mounted; comprising the steps of making a motor sub-assembly including a motor (4) and a radial fan (2), the fan having a plurality of blades (16) located on one side of the fan and non-rotatably mounting the fan on an end of the armature shaft of the motor at a first end of the motor with the blades (16) facing away from the armature of the motor. Then balancing the motor sub-assembly. Then mounting the sub-assembly within the housing, with the longitudinal axis of the motor armature shaft at an angle, preferably perpendicular to the longitudinal axis (3) of the spindle and with the first end of the motor closest to the spindle axis (3).

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in anti-phase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool.

Abstract: A hand held electrically powered drilling and/or hammering tool comprises a balanced motor sub-assembly including a radial fan mounted to the armature shaft at a first end of the motor with the fan blades facing away from the motor, and motor the sub-assembly is mounted with the axis of the motor angled with respect to the axis of the tool spindle and with the first end of the motor closest to the spindle, and an air outlet is located in the housing near a second end of the motor, and the above components are arranged so that rotation of the fan draws air into its inlet via air inlets and then pushes air from its outlet through the motor and out of the air outlets in the region of the second end of the motor which is remote from the spindle axis.

Abstract: A vibration reduction apparatus (501) for use with a hammer tool having a hammer piston (520) is shown. The hammer piston (520) is cansed to reciprocate in cylinder (530) by rotation of a gear wheel (523) about axis (524), the hammer piston (520) being mounted to the gear wheel (523) via piston arm (531) and pivot pin (522). Reciprocating motion of the hammer piston causes a flying mass (569) to be driven along cylinder (530) to impart a hammer action to a bit of the tool. The gear wheel (523) is caused to rotate about axis (524) by meshing of gear (514) on drive shaft (511) with gear teeth (532) on the periphery of gear wheel (524), the drive shaft (511) being caused to rotate by a motor (not shown) of the tool. a cam (533) is rigidly mounted around gear wheel (523), a counterweight 5219 surrounds piston cylinder (530), and a cam follower (534) is provided on counterweight 521. The cam follower 534 on counterweight 521 is urged into contact with cam (533) by means of a compression spring (535).

Abstract: A method of assembling a hand held electrically powered drilling and/or hammering tool having a tool housing and a drilling and/or hammering spindle mounted within the housing, which spindle has a forward end at which a tool or bit may be mounted; comprising the steps of making a motor sub-assembly including a motor (4) and a radial fan (2), the fan having a plurality of blades (16) located on one side of the fan and non-rotatably mounting the fan on an end of the armature shaft of the motor at a first end of the motor with the blades (16) facing away from the armature of the motor. Then balancing the motor sub-assembly. Then mounting the sub-assembly within the housing, with the longitudinal axis of the motor armature shaft at an angle, preferably perpendicular to the longitudinal axis (3) of the spindle and with the first end of the motor closest to the spindle axis (3).

Abstract: A hand held electrically powered hammer comprises a housing, a motor, and a hollow spindle. A piston and a ram are located for reciprocation within the spindle. A casing encloses at least part of the spindle so as to define a chamber between the spindle and the casing. A damping mass is slideably supported by a spacer and is located within the chamber and is connected to the hammer housing via a spring so as to oscillate back and forth along the spindle to minimize the vibration of the hammer housing and also so as to generate air flows within the chamber for facilitating heat transfer from the spindle to the metal casing.

Abstract: A hand held electrically powered hammer, comprising a housing, a motor, a hollow spindle within which is located for reciprocation therein a piston and a ram, and a casing which encloses at least part of the spindle so as to define a chamber between the spindle and the casing and wherein a damping mass is located within the chamber and is connected to the hammer housing via at least one spring element so as to oscillate back and forth along the spindle to minimise the vibration of the hammer housing, and also so as to generate air flows within the chamber for facilitating heat transfer from the spindle to the casing.

Abstract: A fan arrangement has an inlet bounded by an edge portion. A rotor has impeller blades which respectively sweep past the inlet. The edge portion forms an angle with each of the impeller blades so that noise generated by the blades during their rotation is substantially reduced. The edge portion may have any arbitrary shaped outline, such as linear, annular or curvilinear.