Abstract: A drilling and/or percussive hammer comprises a handle and a hammer housing, which can move relative to the handle and inside of which, among other things, a pneumatic spring percussive mechanism is housed. The pneumatic spring of the pneumatic spring percussive mechanism can be ventilated via a no-load operation duct that is opened and closed by a valve. The valve can be opened and closed according to a pressing force acting upon the handle. A delay device controls the valve during closing so that the valve reaches the position corresponding to the detected pressing force only with a time delay. This causes a smooth transition from the no-load operation to the percussive operation.

Abstract: A power tool according to the invention includes a dynamic vibration reducer having a body, a weight and elastic elements. The body is formed by a plurality of cylindrical members which are coaxially disposed to face each other. The elastic elements exert biasing forces on the cylindrical members such that the cylindrical members are held apart from each other. The cylindrical members are fixed to the tool body side under the biasing forces of the elastic elements. Venting members for forced vibration are provided on the cylindrical members and protrude radially outward from the cylindrical members, respectively. The venting members are mounted by inserting into venting member mounting parts on the tool body side in a direction transverse to the longitudinal direction of the cylindrical members. At least one of the venting members can move with respect to the cylindrical member in the longitudinal direction.

Abstract: A hand-held power tool includes a work spindle (4)in which a chuck (3) for receiving an axially displaceable, within limits, percussion working tool (2), is mounted on. The work spindle (4) having a coaxial die (5) located in its interior for imparting blows to the percussion working tool (2). At least one cooling air channel (7) extends in an outer housing (6) radially outwardly of the work spindle and opens into a chuck free space (8) which adjoins the work spindle (4). The at least one cooling air channel (7) communicates with the interior of the work spindle through an opening (10, 10?) formed in the work spindle. A seal (9, 9?) completely flowtight seals the free space (8) outwardly.

Abstract: A hydraulic breaker assembly including a head cap, a cylinder, and a front head, which are mounted in a casing, wherein corresponding faces of the front head and the cylinder are connected by connecting pins, wherein the cylinder and the head cap located above the cylinder are fixed together by fastening bolts, and wherein the front head, the cylinder, and the head cap are supported on an inner side of the casing by variable dampers, which are brought into close contact with the front head, the cylinder, and the head cap. The movement in the casing is thus prevented so that the head cap, the cylinder, and the front head are strongly coupled together. The length of the fastening bolt is reduced to minimize the impact-generating section so that the bolt is protected from distortion stress occurring upon striking of the rod, thereby increasing durability.

Abstract: Disclosed is a hydraulic breaker.

Abstract: The present invention relates to a method for controlling a power tool comprising a housing, an electric motor, a tool holder for supporting a tool bit and a conversion mechanism for converting the rotational movement of the output shaft of the motor into a reciprocating movement of the tool bit when being supporting in the tool holder, wherein oscillations of an element of the power tool are detected, wherein a quantity characterizing the oscillations is monitored and wherein the rotational speed of the electric motor is controlled such that the quantity does not exceed a preset value.

Abstract: A hammer drill having a clutch pin and a clutch mechanism is provided. By switching the clutch mechanism, a selection can be made between a hammer drill mode and a hammer mode. The clutch pin is configured to be slidable to a sliding position where the clutch pin runs through the reduction shaft so as to be capable of protruding beyond the reduction shaft, and at the sliding position, the clutch pin engages with an engagement hole provided on the tool holder side so that a rotation of the tool holder can be locked, whereby in the hammer mode, a selection can be further made between a neutral state where the clutch pin does not engage with the engagement hole and a rotation locked state where the clutch pin engages with the engagement hole.

Abstract: A hand-held power tool, in particular an electrical hand-held power tool (1), includes a drive motor (4), a tool shaft (14), and a first overload clutch (19) for limiting the maximum torque that acts on the tool shaft (14). Preferably, the hand-held power tool also includes a second overload clutch (20).

Abstract: The invention is based on an electric power tool having at least one drive unit and a gear unit, where the gear unit is a drive element for applying force to a piston unit. It is proposed that the drive element and the piston unit be arranged in an axially parallel manner. At least a region of the drive element overlaps axially with a longitudinal portion of the piston unit. The drive unit is arranged approximately centrally in an axial extension of the piston unit and the longitudinal axis of the drive unit is arranged transversely to the piston longitudinal axis.

Abstract: A handheld power tool has a housing, a tool receptacle, a motor having a motor shaft, an intermediate shaft, an element for transmitting a rotation of the motor shaft to a rotary motion of the intermediate shaft, a drive mechanism for a tool insertable into the tool receptacle, the drive mechanism being provided with an element for converting the rotary motion of the intermediate shaft into a rotary motion of the tool receptacle and an element for converting the rotary motion into the intermediate shaft into a hammering motion of the tool receptacle, wherein the motor shaft is coaxial with the intermediate shaft, and there is an element for coupling the motor shaft to the intermediate shaft.

Abstract: The invention is a striking mechanism for a handheld power tools in particular electric hammer. A piston is arranged in an axially bidirectionally movable manner in a guide tube. A striker is provided which acts on a striking pin and which is held in a movable manner in the guide tube. A compression space is delimited by the piston and the striker such that an air cushion is enclosed therein. It is proposed that at least one spring element is provided between the striker and the striking pin.

Abstract: According to an aspect of the invention, an oil pulse tool includes: a motor generating a driving force; an oil pulse unit including a shaft, the oil pulse unit being driven by the motor and generating an impact torque on the shaft when the motor passes an impact position; and an output shaft on which a front end tool is attached, the output shaft being fixed to the shaft, wherein the oil pulse tool is provided with a rotational position detecting sensor of detecting a rotational position of the output shaft, and a torque detecting sensor of detecting generation of an impact torque, and the oil pulse tool is provided with detecting means for measuring a state required for reversely rotating the motor by generating an impact, and regularly rotating again the motor and passing a position of generating the impact, and detecting a reduction in a performance of the oil pulse unit by an aging change of the state.

Abstract: A hammer comprising: a body; a tool holder mounted on the body for holding a cutting tool; a handle pivotally mounted on the body about an axis; a vibration dampener which connects between the handle and the body and which reduces the amount of angular vibrations transmitted from the body to the handle; a motor mounted within the body; a hammer mechanism mounted in the body, capable of being driven by the motor when the motor is activated, the hammer mechanism, when driven, imparting impacts onto a cutting tool 6 when held by the tool holder; wherein the handle is pivotally mounted about a pivot axis which passes through the centre of gravity of the hammer.

Abstract: It is an object of the invention to provide a rational forced vibration of a dynamic vibration reducer in an impact tool that linearly drives a tool bit in an axial direction of the tool bit via a swinging member. An impact tool includes a motor 111, a swinging member 129 that swings in the axial direction of a tool bit 119 by rotation of the motor 111, a driving element 141 that is caused to reciprocate by swinging movement of the swinging member 129 and a first air chamber 143a in which pressure is fluctuated by reciprocating movement of the driving element 141, and the tool bit 119 is driven by pressure fluctuations of the first air chamber 143a. The impact tool further includes a second air chamber 163 in which pressure is fluctuated by swinging movement of the swinging member 129, and a dynamic vibration reducer 151 having a weight 155 and an elastic element 157 which exerts a biasing force on the weight 155.

Abstract: A hand-held power tool includes a percussion power tool includes a percussion piston (5) for applying blows to an anvil (8) axially displaceable in a guide tube (6) within limits defined by two, spaced from each other, stops (9a, 9b) arranged in the guide tube (6), a pneumatic percussion mechanism (2) for driving the percussion piston (5), an air spring (3) for connecting the percussion piston (5) with the percussion mechanism (2), and an impact ring (12) arranged coaxially with the anvil (8) outwardly thereof and having spaced from each other, inner radical flanks (14) located on opposite axial sides of the outer radial collar (11) provided on the anvil (8), with the impact ring (12) freely axially displaceable, within limits, relative to the outer radial collar (11) and having an outer diameter smaller than a guiding inner diameter of the guide tuber (6), and with a mass ratio of the impact ring (12) to the anvil (8) being equal at least 0.25.

Abstract: A hand-held power tool includes a main handle, a percussion mechanism striking along a percussion axis, a counter mass displaceable along an oscillation axis which is inclined to the percussion axis and biasing elements for preloading the counter mass to a rest position on the oscillation axis. The counter mass is arranged such that the rest position is closer to the main handle than the center of gravity is to the main handle.

Abstract: A hand-held power tool (1) includes a linear motor (2) having a rotor (3) which is movable along a percussion axis (A) in an axially limited manner between two reversal points (W) and which can be driven by the striking piston (5) of the power tool with the intermediary of an air spring (4), sensors designed for determining the actual state of the rotor (3) and connected to a computer (9) connected via power electronics (33) to at least one field coil (10) of the linear motor (2), with the rotor (3) being displaced against a contact element (11a, 11b) at least at one reversal point (W) and being pressed against the contact element electromagnetically; and a control process for the hand-held power tool.

Abstract: A hand-held power tool includes a pneumatic percussion mechanism having a percussion piston reciprocating along a percussion axis and having a bore extending at an angle to the percussion axis, and an air spring for displacing the percussion piston.

Abstract: A torque overload clutch for an electrical power tool, such as a percussion hammer drill, is provided. The clutch is accommodated in a cavity in a gear cog. Spring washers are used to urge ball bearings into indentations formed in the base of the cavity. The ball bearings are accommodated in cavities formed in a drive plate which engages with the spindle drive of the power tool. The spring washers are held in position by a circlip or a threaded plate. The threaded plate arrangement provides means for compressing the spring washers with a consistent force across a manufactured batch. A method of manufacturing the clutch is also disclosed.

Abstract: The present invention relates to a pulse generating device for inducing a shock wave in a tool, wherein the said pulse generating device comprises an impact means (201; 301) for transferring energy to a drill string (202) connected to the said tool, and wherein the energy transfer gives rise to the said shock wave, in which the said energy is mainly constituted by elastic energy stored in the impact means (201; 301) and/or an energy store. The device comprises control means for controlling the interaction of the impact means (201; 301) with the drill string (202), wherein the said control means for controlling the interaction of the impact means (201; 301) with the drill string (202) comprises a motor (207; 307), and wherein the said motor (207; 307) is designed to, through rotation, alternately open ducts for pressurization and depressurization of at least one drive surface (205) acting upon the said impact means.

Abstract: It is an object of the invention to provide a technique which is effective in improving the durability of an angular positioning device of a tool bit and in reducing weight of a tool body in an impact tool. A representative impact tool includes a tool body, a lubricant sealed in the housing space, a driving mechanism, a tool holder, an angular positioning device disposed on a tip end side of the tool body and serves to fix a position of the tool bit around the axis with respect to the tool body. The angular positioning device includes first and second locking members. The first locking member is disposed between the tool body and the tool holder. The second locking member is disposed opposite to the first locking member. One end of the first locking member in the axial direction of the tool bit extends into the housing space of the tool body and is connected to the tool body within the housing space.

Abstract: The machine tool includes a pneumatic percussion mechanism having a cup-shaped exciter cylinder (21) with an inner chamber (31) which is open in the direction of impact (26), and a free piston (22) which is movable in the inner chamber (31). A recess (32) and at least one ventilation opening (35), spaced at a distance from the recess (32) in the direction of impact (26), are provided in a shell-type wall (39) of the inner chamber (31). The free piston (22) includes a sealing element (53) which seals off the at least one ventilation opening (35) when the sealing element (53) is oppositely situated from the at least one ventilation opening (35), and which in the region of the recess (32) is separated at a distance from the shell-type wall (39) when the sealing element (53) is oppositely situated from the recess.

Abstract: A vibration hammer is provided, including a main body; a striking unit having a piston housing installed to he elevated by a hydraulic pressure controlling valve unit installed in the main body, a hammer guide slidably installed on the main body to be coaxial with the piston housing, and a piston having both ends fixed to the piston housing and a hammer guide and elastically deformable at a predetermined angle with an elevating direction of the piston housing; and a rotating unit installed in the main body and reciprocally rotating the hammer guide elevated together with the piston. The vibration hammer can prevent the piston from being damaged by being elastically deformed when a lateral pressure applied to the rod connected to the piston.

Abstract: A pneumatic striking mechanism includes a guide cylinder in which a freely moving piston and an exciter piston are arranged movably along a striking axis. The guide cylinder has a plastic. The striking mechanism includes a pneumatic chamber sealed off by the guide cylinder, by the freely moving piston and by the exciter piston, as well as a drive for periodically moving the exciter piston, as a result of which the freely moving piston is excited to execute a periodical movement between the striking surface and the exciter piston.

Abstract: A powered hammer includes a housing, a tool holder coupled to the housing and configured to hold a tool, a motor within the housing, a cylinder disposed within the housing, and a piston slideably mounted within the cylinder. A drive mechanism converts rotary output of the motor into a reciprocating motion of the piston. The drive mechanism includes a crank shaft rotationally driven by the motor, a drive pin eccentrically mounted on the crank shaft, and a con rod with a first end connected to the drive pin and a second end connected to the piston. A ram is slideably mounted forward of the piston that is reciprocatingly driven by the piston. A beat piece is slideably mounted forward of the ram. The beat piece is repetitively struck by the reciprocating ram, which in turn repetitively strikes an end of the tool when held in the tool holder to transfer the momentum of the ram to the tool. Lubrication fluid covers at least part of the drive mechanism.

Abstract: A pneumatic hammer mechanism is disclosed. The hammer mechanism features: a flying mass, which is movable along an impact axis; an impact surface, which limits a movement of the flying mass along the impact axis in the impact direction; a hammer piston, which limits a movement of the flying mass along the impact axis opposite from the impact direction; a pneumatic chamber between the flying mass and hammer piston; a drive for periodically moving the hammer piston with a stroke along the impact axis, wherein the flying mass is excited to a periodic movement between the impact surface and hammer piston. The stroke is selected as a function of a maximum length of the pneumatic chamber such that the periodic movement of the flying mass on the path between an impact on the impact surface and a minimum approach of the hammer piston intermittently has a velocity of zero.

Abstract: A pneumatic hammer mechanism is disclosed. The hammer mechanism features: a flying mass, which is movable along an impact axis; an impact surface, which limits a movement of the flying mass along the impact axis in the impact direction; a hammer piston, which limits a movement of the flying mass along the impact axis opposite from the impact direction; a pneumatic chamber between the flying mass and hammer piston; and a drive for periodically moving the hammer piston with a stroke along the impact axis. The flying mass is excited to a periodic movement between the impact surface and a minimum approach of the hammer piston. A length ratio of the maximum length of the pneumatic chamber to the stroke is selected as less than 1.55.

Abstract: It is an object of the invention to provide an effective technique for further enhancing the effect of reducing a reaction force inputted during hammering operation. Representative impact tool comprises a tool body, a hammer actuating member, a cylinder and a compression coil spring. The compression coil spring contacts the hammer actuating member and thereby positions the tool body with respect to the workpiece when the hammer actuating member is pressed against the workpiece and pushed rearward in advance of the hammering operation. In such position, the compression coil spring absorbs a reaction force that is caused by rebound from the workpiece and acts upon the hammer actuating member when the hammer actuating member performs the hammering operation on the workpiece. The cylinder is inserted into the tool body from the front along the axial direction of the hammer actuating member and thereby housed within a predetermined housing part of the tool body.

Abstract: An electrical power tool (1) includes a housing (10,20,30), an electrical motor (21), a motion conversion mechanism (36), a counterweight holding member (73), a counterweight (74), and support members (71,72). The electrical motor (21) is accommodated in the housing (10,20,30). The motion conversion mechanism (36) is configured to convert a rotary motion of the electrical motor (21) into a reciprocation motion. The counterweight holding member (73) extends in a direction perpendicular to directions of the reciprocation motion and is capable of being elastically deformed in the directions of the reciprocation motion. The counterweight (74) is supported by the counterweight holding member (73) and is capable of reciprocating in the directions of reciprocation motion together with the counterweight holding member (73). The support members (71,72) are positioned away from the counterweight (74) by a predetermined distance for supporting the counterweight holding member (73) to the housing (10,20,30).

Abstract: A handheld power tool with a rotating and/or hammering drive mechanism for a tool (11) that can be inserted into a tool receptacle (10) has a unit which transmit the rotation of a motor shaft (5) to an intermediate shaft (7), by which the tool receptacle (10) is set into a rotary motion and/or a hammering motion. A compact construction of the handheld power tool is attained by providing that the motor shaft (5) is coupleable or is coupled to the intermediate shaft (7) in one axis.

Abstract: A drilling and/or percussive hammer comprises a handle (10) and a hammer housing (1), which can move relative to the handle (10) and inside of which, among other things, a pneumatic spring percussive mechanism (4) is housed. The pneumatic spring of the pneumatic spring percussive mechanism (4) can be ventilated via a no-load operation duct (13, 15, 17, 26, 27) that is opened and closed by a valve (16, 17, 25). The valve (16, 17, 25) can be opened and closed according to a pressing force acting upon the handle (10). A delay device (18, 20, 21, 29, 30) controls the valve (16, 17, 25) during closing so that the valve reaches the position corresponding to the detected pressing force only with a time delay. This causes a smooth transition from the no-load operation to the percussive operation.

Abstract: A hydraulic breaker assembly including a head cap, a cylinder, and a front head, which arc mounted in a casing, wherein corresponding faces of the front head and the cylinder are connected by connecting pins, wherein the cylinder and the head cap located above the cylinder are fixed together by fastening bolts, and wherein the front head, the cylinder, and the head cap are supported on an inner side of the casing by variable dampers, which are brought into close contact with the front head, the cylinder, and the head cap. The movement in the casing is thus prevented so that the head cap, the cylinder, and the front head are strongly coupled together. The length of the fastening bolt is reduced to minimize the impact-generating section so that the bolt is protected from distortion stress occurring upon striking of the rod, thereby increasing durability.

Abstract: An air spring hammer device that includes a drive piston, moving axially back and forth, with a front face of hollow embodiment and a hammer piston moving in said hollow. A ventilation slot is embodied in a guide wall of the drive piston. The drive piston may be guided in a guide tube. The guide tube comprises several idle openings. A moving control element is arranged on the exterior of the guide tube, in which control openings, corresponding to the idle openings, are provided. In an idle operating mode, the control element is in an open position, via which the ventilation slot, the idle openings and the control openings can be brought into connection with the environment.

Abstract: A rotary hammer includes a housing, a tool holder mounted on a front portion of the housing, and a motor mounted in the housing. The motor includes an armature shaft arranged substantially perpendicular to an axis of rotation of the tool holder and including toothing. A hammer mechanism is driven by the motor to generate impacts on a tool being held by the tool holder. The hammer mechanism includes a first intermediate shaft adjacent and substantially parallel to the armature shaft facing away from the tool holder. A rotation drive mechanism is driven by the motor to rotatingly drive a tool being held by the tool holder. The rotation drive mechanism includes a second intermediate shaft adjacent and substantially parallel to the armature shaft facing the tool holder. The toothing of the armature shaft meshes with corresponding toothing on at least one of the first intermediate shaft and the second intermediate shaft.

Abstract: A hand-held power tool includes a pneumatic percussing mechanism (3) located in the power tool housing (2) and having an anvil (5) and a percussion piston (4) for applying blows to the anvil (5), and at least one oscillation damper (6, 6?) including an oscillation damping mass (7, 7?), at least one spring (8a, 8a?) for compressively preloading the damping mass (7, 7?) against the power tool housing (2), and an axially displaceable excitation member (9) for actively exciting the oscillation damper (6, 6?) in response to the anvil (5) occupying an operational position.

Abstract: A hand power tool has a percussion mechanism; a drive motor that drives the percussion mechanism; a conversion element for converting a movement of the drive motor into an axial movement; and an operating unit that adjusts a rotary movement of the conversion element within a percussion period depending on at least one optimization criterium.

Abstract: The invention relates to a percussion device having a body and a percussion piston moving therein, pressure fluid spaces in the rear and front ends of the percussion piston and pressure fluid channels for feeding pressure fluid into the percussion device. The percussion piston and the control valve comprise surfaces, which, when aligned, substantially close the pressure fluid flow from the pressure fluid space locating behind the percussion piston in front of the control valve, whereby the produced pressure displaces the control valve to another position.

Abstract: A hand-held power tool having a main housing (4) in which a tool spindle (10) is at least partially located, and a handle housing (16) on which a handle (18) is formed, includes a connection device (28) for securing the handle housing (16) to the main housing (16) and having a first connection element (50) with a first engagement member (58) loosely engageable with a second engagement member (52) associated with the main housing (4), and a second connection element (48) with a handle-side locking element, a main housing side locking element, and a further locking element for formlockingly connecting the handle-side locking element and the main housing side locking element, whereby absence of loose engagement of the first and second engagement members is ensured upon formation of the formlocking connection of the handle-side and main housing side locking elements.

Abstract: A device for a drilling hammer and/or percussive hammer has a tool holding fixture for holding a tool and for transmitting a torque to the tool. A component of the tool holding fixture consists of a hollow cylindrical tool holder, which has an insertion opening for an insertion end of the tool, and has an impact opening, via which a percussive action can be applied to the insertion end. A stopping surface, which is stationary with regard to the tool holder and which acts in an axial direction of the tool holder, is provided in the tool holder in the area of the impact opening. The tool holding fixture is particularly suited for insertion ends according to the SDS-max standard.

Abstract: An electrical power tool includes a housing, an electrical motor, a motion conversion mechanism, a weight-supporting member, a counterweight, and a first supporting member and a second supporting member. The first supporting member and the second supporting member are each provided on the housing for supporting the weight-supporting member to the housing. The weight-supporting member has a first connecting part and a second connecting part supported by the first supporting member and the second supporting member, respectively; and an elastically deforming part. The elastically deforming part is positioned between the first connecting part and the second connecting part and has a mounting part for mounting the counterweight. The elastically deforming part includes a portion having a smaller cross-sectional area than each cross-sectional area of the first connecting part and the second connecting part.

Abstract: A hand-held drill hammer has a housing, a shaft (12) connected to a drive shaft (30), and a lifting bearing (14). The lifting bearing (14) is supported and the shaft (12) for converting rotary motion into a reciprocating motion. In a first switching configuration, a percussion drive connection exists between the shaft (12) and the lifting bearing (14). In a second switching configuration, the percussion drive connection is interrupted. The lifting bearing (14) may be fixed with respect to a reference system of the housing in the second switching configuration.

Abstract: A hammer drill for manually guided operation includes an electric drive motor, a tool spindle and a pneumatic hammer function. The hammer drill includes a pressure piston, a striker, and a beat piece for striking axially against a tool that is held by the tool spindle. When the striker reaches a forward limit position, an end section thereof protrudes into a retaining ring that is aligned coaxially with the spindle axis. Manufacturing quality can be improved by bracing the retaining ring against an annular collar in the tool spindle on the one side and axially against a locking ring set in an annular groove conformed in the tool spindle via a retaining disc on the other side. The retaining ring, the retaining disc and the non-return disc are each mirror-symmetrical.

Abstract: According to one aspect of the invention hydraulic pressure pulses are created in a rock drill machine utilizing a rod (7, 7a, 7b) made of a magnetostrictive material arranged in one or more actuators (5, 5a, 5b), which exposes an impulse piston (3) in a pulse cylinder (1) to said hydraulic pressure pulses, whereby mechanical pressure pulses being transferred to a drill steel of the rock drill machine are generated in the impulse piston (3).

Abstract: A tool fitting that is provided to accommodate a rotary hammer bit and/or a chisel bit (10) and an adapter (12). The tool fitting has centering elements (14, 16) for at least reducing the mobility of the adapter (12) when mounted in comparison to the mobility of the rotary hammer bit and/or chisel bit (10) when mounted.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in a power impact tool that linearly drives a tool bit by using a swinging mechanism. According to the invention, a representative power impact tool is provided with a motor, a rotating shaft, a swinging member, a tool driving mechanism and a counter weight. The swinging member is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft. The counter weight is disposed in a region higher than a lower end region of the swinging member in the vertical direction to intersect with the axis of the rotating shaft, and a lower end of the counter weight is connected to the lower end region of the swinging member.

Abstract: A hand-held hammer drill has a housing, a tool spindle rotatingly driving a tool, a hammer action percussion-driving the tool, a swash plate drive driving the hammer action, and a countershaft driving as needed the tool spindle and the hammer action. A first bearing and an axial bearing are provided. The hub is rotatably supported in a cantilevered arrangement by the first bearing in the housing and coaxially surrounds the countershaft. The hub has a free cantilevered end and the axial bearing is disposed on the free cantilevered end, wherein the axial bearing axially supports the countershaft and has radial play relative to the countershaft.

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 hand-held power tool for at least percussively driving a working tool (2) along a percussion axis (A) and including a chuck (4) for receiving the working tool (2) and including a receiving sleeve (6, 6?) fixedly connected with the chuck (4) for joint rotation therewith and for limited axial displacement relative thereto, at least one locking member (7) radially displaceably supported in the receiving sleeve (6, 6?) for axially securing therein a shank (3, 3?) of the working tool (2) insertable in to the receiving sleeve (6, 6?), and an axially extending anvil (8) securable in the receiving sleeve (6, 6?) for closing a power tool side end of the receiving sleeve (6, 6?).

Abstract: A hand-held power tool includes a pneumatic percussion mechanism having a percussion piston reciprocating along a percussion axis and having a bore extending at an angle to the percussion axis, and an air spring for displacing the percussion piston.

Abstract: When the mode change knob of a multi-mode hammer drill is moved to the hammer only position, an electronic sensor sends a signal to a control logic circuit. When the user then depresses the trigger mechanically closing the ON/OFF switch, the control logic circuit applies a voltage either to a holding relay or to the gate of a triac which enables the relay or triac to conduct, thus providing a parallel circuit by-passing the ON/OFF switch. Consequently, when the user releases the trigger and opens the ON/OFF switch, the parallel relay or triac maintains current flow to the motor. It can be seen that in hammer only mode the user can activate the hammer drill by simply tapping the trigger to depress it and does not need to hold down trigger during use of the hammer in operation.