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: The invention relates to a hand-held working tool, having a first unit, powered by a vibration on operation and a second unit which may be displaced relative to the first unit. A vibration isolation device is arranged between the first and second unit, having an actuator, for generation of a control force. An operational force acting in the working direction (A) between the first and the second unit may be at least partly compensated by the control force. The actuator is pneumatically operated and comprises an air spring for vibration isolation. A working piston in an air spring percussion device on the working tool serves to supply compressed air for the air spring. Alternatively, the compressed air can be supplied by the oscillating relative movement between the first unit and the second unit.

Abstract: An impact tool is provided that can efficiently reduce the vibration resulting from the striker and that does not lead to a larger design even with the use of a counterweight mechanism. A counterweight mechanism is provided in a motion converter housing, facing the handle. The counterweight mechanism is positioned between a center of gravity of the impact tool and the grip of the handle and is positioned above the control substrate. The counterweight mechanism is equipped with a first support, a second support, a weight support member, and a counterweight.

Abstract: A hand held motor driven electrically powered tool, in particular a rotary hammer, comprising a spindle (40) for rotatingly driving a tool or bit (68), a spindle rotary drive train (14, 5, 10) for rotatingly driving the spindle (40) and an arrangement for detecting blocking events (16, 17). Blocking events occur when the tool or bit of the tool become rotationally fixed in the material being bored in which case the rotary drive on the spindle from the motor causes the tool housing to rotate in a user's grip.

Abstract: The invention relates to a method for controlling the operation of a pressure fluid operated percussion device and to a pressure fluid operated percussion device. The method comprises influencing the shape of a stress wave by setting a suitable clearance between a transmission piston and a tool. The percussion device is provided with means for setting the clearance between the transmission piston and the tool.

Abstract: A device (1) which includes an elongate body (2) with a movable mass (3) arranged for sliding movement within the body (2), the element (4) being arranged to decelerate toward an end of the body (2) in order to impart forward movement thereto, via momentum transfer, and being arranged to accelerate away from said end in order to further drive the body (2) forward, again using momentum transfer.

Abstract: A hand-held power tool includes a motor-driven percussion mechanism including a guide tube (21), a reciprocating driving member (22) displaceable in the guide tube (21) for driving, via a gas spring, an impact member (23) likewise displaceable in the guide tube (21) a motor-driven eccentric wheel (17) rotatable about an axis (D) which is spaced from the percussion mechanism axis (S) in a direction perpendicular to the percussion mechanism axis (S) by a distance (X), and a connection rod (29) eccentrically supported on the eccentric wheel (17) and connected to the driving member (22) for converting a rotational movement of the eccentric wheel (17) into a reciprocating movement of the driving member (22).

Abstract: A pulse tool, in particular a pulse nutsetter, has a drive unit and a pulse unit driven by it. The pulse unit has at least one rotor with at least two vanes, a hydraulic cylinder surrounding it and a drive spindle protruding at one end out of the hydraulic cylinder through a front plate. The front plate is arranged between the rotor and a front cover, said cover being formed with a hydraulic fluid filling device. In order to improve a pulse tool of this nature, in that deviations from the desired pulse frequencies can be compensated in a simple manner and in particular already during the assembly of the pulse tool, the front plate has at least one bypass opening connecting the high-pressure and low-pressure chambers which are separated by the vanes. The invention also relates to an appropriate front plate.

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: It is an object of the invention to provide an improvement in ease of operation of a driving mode switching mechanism in a hammer drill. According to the invention, a representative hammer drill includes a driving mode switching mechanism which has an operating part, a first switching member and a second switching member. The operating part can be turned to at least three rotating positions in its circumferential direction, while the operating part can be turned 360° on the rotation axis in the both directions. Thus, the user can select the desired driving mode in the shortest turning distance without passing through an unnecessary driving mode position. Therefore, ease of operation in mode change can be enhanced.

Abstract: An electric power tool, in particular an electric hammer, having a drive unit (11) contained in a housing (10), an impact mechanism (12), and a handle (13), including a cam (14) that is driven by the drive unit (11); the impact mechanism (12) has moving parts (15, 16). At least two of the moving parts (15, 16) are able to move inside a separate guide cylinder (17) that is stationary in relation to the moving parts (15, 16) and the cam (14).

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: An overload clutch assembly for a power tool having two torque settings through which rotary drive is transmitted to a spindle. The overload clutch assembly is capable of being between switched between the two torque settings by at least one actuator. The clutch assembly comprises a carrier rotationally mounted on a output clutch spindle; a first clutch plate operational for transmitting torque below a first level; and a second clutch plate operational for transmitting torque below a second level higher than the first; and characterised in that, when the overload clutch is in the higher torque setting, the torque is transferred from the carrier to the output clutch spindle via the second clutch plate only.

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 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: It is an object of the present invention to provide an improved technique for preventing leakage of lubricant from an accommodating space that houses a driving mechanism, while regulating the internal pressure of the accommodating space in a power tool. A representative power tool includes a power tool body, a tool bit, a driving mechanism, a lubricant, an accommodating space, a passage and a lubricant leakage preventing region. The accommodating space is disposed in the body to house the driving mechanism and is hermetically sealed. The passage has an accommodating space side opening and an outside opening. The passage extends, starting from the accommodating space side opening, in a direction away from the outside opening. Then, the passage turns around and extends toward the outside opening. Further, the lubricant leakage preventing region is provided with the passage to prevent the lubricant from leaking from the inside to the outside of the accommodating space.

Abstract: A wobble device (20) for a hand-held power tool (2) and which includes a rotatable drive member (22), a driven member (26) oscillatingly pivotable about a wobble axis (T) and a wobble bearing (30) for connecting the driven member (26) with the drive member (22) and having a drive-side bearing region with a drive-side guide (34) circumferentially arranged about the drive axis (A) and provided on the drive member (22), a driven-side bearing region with a driven-side guide (38) circumferentially arranged about the drive axis (A) and provided on the driven member (26) and roll elements (28) guided simultaneously in both guides (34, 38), and with one of the bearing regions having on its first side (46, 48; 50, 52) with respect to an associated guide (34; 38), a reinforced cross-section in comparison with a second side (48, 46; 52, 50) of the one region.

Abstract: A vibration reduction and lubricating mechanism for a powered hammer includes a power driven piston in a cylinder that reciprocatingly drives a ram, which repetitively strikes a beat piece, which repetitively strikes a tool received in a tool holder. The vibration reduction and lubricating mechanism includes a first chamber defined in a housing of the powered hammer. A second chamber is defined within an end portion of the cylinder facing the beat piece, forward of the ram. A passageway is in communication with the first and second chambers. A counter mass is mounted for oscillating movement within the first chamber. When the hammer is operated, the counter mass is caused to oscillate to counteract vibration in the housing and to cause lubrication fluid to move between the first and second chambers.

Abstract: A hand-held power tool includes a percussion mechanism (2) having a percussion piston (5) for impacting at least one anvil (8, 8?a, 8?b) displaceable in a guide tube (6) between two, spaced from each other axial stops (7a, 7b) provided in the guide tube (6), and an impact sleeve (10, 10?) arranged coaxially with the at least one anvil (8, 8?a, 8?b), axially displaceable within limits between two outer radial bands (9a, 9b, 9?) formed on the at least one anvil (8, 8?a, 8?b), and having an outer diameter (A) smaller than an inner diameter (I) of the guide tube (6).

Abstract: The present invention is directed to a switching device with a rotatably mounted operating element (10) and an eccentric element (12) for translating a rotational displacement (14) of the operating element (10) into a translatory displacement (16) of a switching element (18), in particular a selector shaft of a hand-held power tool. It is provided that a shape of the eccentric element (12) differs significantly from that of a rod.

Abstract: It is an object of the invention to provide an improved technique for lessening an impact force caused by rebound of a tool bit after the striking movement of the tool bit. Representative impact power tool (101) includes a tool body (103), a hammer actuating member (119, 145), a driving mechanism (113, 115), a weight (163) and an elastic element (165). A reaction force that the hammer actuating member receives from the workpiece when performing a hammering operation is transmitted from the hammer actuating member to the weight (163) and then, the weight (163) is caused to move rearward to push the elastic element (165). As a result, the reaction force can be absorbed by the elastic element (165). The elastic force of the elastic element (165) is prevented from acting upon the weight (163) forward beyond the reaction force transmitting position.

Abstract: An overload clutch assembly for a power tool having two torque settings through which rotary drive is transmitted to a spindle. The overload clutch assembly is capable of being between switched between the two torque settings by at least one actuator. The clutch assembly comprises a carrier rotationally mounted on a output clutch spindle; a first clutch plate operational for transmitting torque below a first level; and a second clutch plate operational for transmitting torque below a second level higher than the first; and characterised in that, when the overload clutch is in the higher torque setting, the torque is transferred from the carrier to the output clutch spindle via the second clutch plate only.

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 transmission housing for a hammer drill comprises two clamshell halves and that mate to define a first transmission housing chamber and a second transmission housing chamber disposed on either side of a ball bearing race. The first and second transmission housing chambers are interconnected by channels. The rear end of a hollow piston, a cylindrical bearing, a crank pin and a crank plate are disposed in the first transmission housing chamber, and a spindle is disposed in the second transmission housing chamber. Overflow channels and allow movement of air between the first and second transmission housing chambers to reduce compression of air iduring reciprocation of the hollow piston.

Abstract: A switching mechanism switches on and off transmission of a striking force to a working tool, and switches on and off transmission of a rotational force to the working tool, thereby switching operation modes among at least a rotation and strike mode, a strike only mode, and a neutral mode. A rotation locking mechanism engages a cylinder during the strike only mode, thereby locking rotation of the cylinder. During the neutral mode, the transmission of the striking force, the transmission of the rotational force, and the locking of rotation of the cylinder are all turned off.

Abstract: The object of the invention is to ease of operation of the power impact tool. Such object is achieved by a representative power impact tool according to the invention including a motor, a tool bit, a trigger and a mode changing member. The trigger is manually operated by a user to control energization and non-energization of current to drive the motor. The motor is energized when the user operates the trigger to turn on and the energized state of the motor is maintained until the trigger is again operated in a same manner with the turning-on operation. According to the invention, once the trigger is depressed from the initial position to the operating position, a hammering operation can be performed by the striking movement of the tool bit without the need to lock the trigger in the operating position. Therefore, ease of operation of the hammer drill is enhanced.

Abstract: A gear wheel is rotatably mounted on a drive shaft. The drive shaft has a plurality of longitudinal splines formed thereon. A drive sleeve surrounds the drive shaft and has a plurality of the inner splines formed on its interior surface. The inner splines slidably intermesh with outer splines of the drive shaft such that the drive sleeve can slide up and down on but cannot rotate relative to the drive shaft. A coil spring biases the drive sleeve downwardly. Drive sleeve teeth are formed around the bottom edge of the drive sleeve. Corresponding gear plate teeth are formed on the upper surface of the gear wheel and are adapted to engage the drive sleeve teeth when the drive sleeve is in its downward most position under the influence of the coil spring. In this position, the gear wheel is operatively coupled to the drive shaft.

Abstract: A hand power tool has an electric motor, which is located in a housing and by way of which a tool insert located in a tool retainer is drivable in rotation, a guard device with which an uncontrollable blockage of the tool insert is detectable via a sensor unit and with which the housing is blockable in its motion; the guard device includes a mechanical unlocking unit that is manually actuatable by a user's action force, and gear is actuatable via an on/off switch for actuating the unlocking unit.

Abstract: A percussion hand-held power tool includes a housing (4), a chuck (2) provided at one end of the housing (4), a handle (3) provided at an opposite end of the housing (4) and secured thereto, an axially displaceable percussion mechanism (5) located in the housing and connected thereto, at its handle side, by a spring (6) and a transversely extending articulated arm (7), and supported in the housing (4), at its chuck side, by axial slide surface element (8).

Abstract: A hand power tool has a housing, and drive motor accommodated in the housing, a tool receptacle in which a tool is guided, a gear mechanism, a driving gear, and rotary sleeve arranged so that via the gear mechanism, the driving gear, and the rotary sleeve the tool receptacle is drivable in rotation, a crank drive mechanism and a hammering mechanism located inside the rotary sleeve so that the tool receptacle is drivable through the crank drive mechanism and the hammering mechanism translationally, and a safety coupling provided between the driving gear wheel and the rotary sleeve and formed so that the safety coupling separates if a limit torque is exceeded, the safety coupling being formed as an overlock coupling seated on the rotary sleeve and having two axially adjacent coupling parts that mesh in a form-locked manner by torque-transmitting transmission elements and are overlockable if the limit torque is exceeded counter to an axially acting elastic force, one of the coupling parts being a part associated

Abstract: A shifting device has a first shifting element, a second shifting element, and a rotatably supported user-operation element including a converter element for converting a rotary motion of the user-operation element into a displacement of the first shifting element in a first direction, the user operation element also including a converter element for converting the rotary motion of the user-operation element into a displacement of the second shifting element in a second direction.

Abstract: An electric power tool includes a percussion mechanism (15) located in an external housing (12) of the power tool (11) and driven by a driving motor (13) connected with the percussion mechanism (15) by a gear unit (14). An arrangement for cooling the power tool (11) includes a fan element (19) located in the external housing for generating a cooling air flow (26), a cooling air channel (18) extending along a longitudinal extent of the percussion mechanism (15) and a cross-section of which has a constriction (21; 51), a fresh air channel (31; 61) having an intake opening (32; 62) for communicating with atmosphere and formed in the external housing (12; 42) and a connection opening (33; 63) for communicating with the cooling air channel (18; 48) and arranged in an area of the constriction (21: 51) of the cooling air channel (18; 48).

Abstract: It is an object of the present invention to provide a power tool having a further improved vibration reducing performance. The representative power tool may comprise a tool bit, an actuating mechanism, a dynamic vibration reducer. The actuating mechanism drives the tool bit linearly by means of pressure fluctuations so as to cause the tool bit to perform a predetermined operation. The dynamic vibration reducer has a weight that reciprocates under a biasing force of an elastic element to reduce vibration of the actuating mechanism. The weight may be driven by means of pressure fluctuations caused in the actuating mechanism. According to the invention, the weight of the dynamic vibration reducer can be actively driven by pressure fluctuations in the actuating mechanism for driving the tool bit. Therefore, regardless of the magnitude of vibration acting on the power tool, the dynamic vibration reducer can be forcedly and steadily operated.

Abstract: It is an object of the invention to provide a reciprocating power tool having a further improved power transmitting mechanism for converting a rotating output of a driving motor into linear motion in the axial direction of the tool bit. The representative reciprocating power tool may comprise a tool bit, a driving motor and a power transmitting mechanism that converts a rotating output of the driving motor into linear motion in the axial direction of the tool bit. The power transmitting mechanism includes an internal gear, a planerary gear, a power transmitting part, a rotation preventing mechanism and an internal gear rotation lock. Further, an internal gear rotation lock prevents the internal gear from rotating in a direction opposite to said predetermined direction. Therefore, the internal gear rotated only in one direction via the internal gear rotation lock and as a result, the internal gear can be reliably locked in a predetermined position without causing rattling.

Abstract: A hand-held power tool includes a percussion mechanism (3) arranged in the tool housing (2), and a motor (4) for driving the percussion mechanism and connected therewith by a gear unit (5), with the percussion mechanism including an eccentric (6) a piston (7), and a connection rod (21; 41) connecting the eccentric with the driving piston (7) and having a first part (22; 42) connectable with the eccentric (6), a second part (23; 43) connectable with the drive piston (7) and telescopically displaceable relative to the first part (22; 42), and a spring for damping vibrations occurring during operation of the power tool and arranged between the first (22; 42) and second (23; 43) parts.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in the power tool, while avoiding complicating the construction of the power tool. According to the present invention, a representative power tool may comprise a striker, a tool bit and a vibration reducer. The vibration reducer serves to reduce vibration on the striker by reciprocating in a direction opposite to the reciprocating direction of the striker. The path of the center of gravity of the vibration reducer is arranged to coincide with a path of the center of gravity of the striker. With such construction, because rotating moment is not exerted onto the reciprocating cylinder during the operation of the power tool, vibration reduction can be performed in a stable manner.

Abstract: An electrically powered hammer is provided comprising a housing, a spindle, a hammering mechanism including a piston reciprocatingly mounted within the spindle, a wobble drive arrangement reciprocatingly connected to the piston, a trunnion arrangement including a cross bolt is driving engaged between the wobble drive arrangement and the piston, and wherein the piston includes a pair of piston arms and a protrusion so that the first piston arm and the protrusion define a first recess and the second piston arm and the protrusion define a second recess, and each of the recesses is shaped so as to support a wear reducing washer in an assembled position. When assembled each washer fits around the cross bolt in a region adjacent the inwardly facing face of the associated piston arm so as to reduce wear between the cross bolt and the piston arms.

Abstract: The invention is based on a power tool having a beater mechanism (14) and a coupling device (12, 100), which can be engaged and disengaged in order to make and break a drive connection (16, 102) of the beater mechanism (14). It is proposed that the coupling device (12, 100) has a synchronizing device (18, 112), with a detent mechanism (20, 110) which transmits a drive moment and which in a synchronizing operation has at least two corresponding detent elements (22, 24, 108), at least one of the detent elements (22) being movable about its detent position upon an overlooking moment, counter to the spring force of a spring element (26, 116).

Abstract: An electrically powered rotary hammer comprising a rotary drive mechanism including a spindle drive gear rotatably mounted around the spindle for rotationally driving the spindle, or a part of the spindle, via an overload clutch. The overload clutch is arranged such that below a predetermined torque threshold a spring element or elements maintain(s) the spindle drive gear and a clutch ring in a relative rotational position in which the spindle drive gear locks locking member or members in a first position and such that above the torque threshold the spring element or elements deform(s) and the relative rotational position of the spindle drive gear and a clutch ring changes so that the locking member or members move(s) out of the first position.

Abstract: An electrical hand-held tool includes an electric motor (2) having a rotor shaft (3) extending transverse to the tool percussion axis (A), a rotor sheet stack (4) supported on the rotor shaft, and a pinion (5) supported on the rotor shaft, a percussion mechanism (6) including an eccentric (7), and a drive gear (8) engageable with the motor pinion (5) for driving the eccentric (7), with the rotor sheet stack (4) being arranged, with respect to the percussion axis A, completely diametrically opposite the drive gear (8).

Abstract: An electric hand tool is disclosed which has a gt (15), received in a housing (10), with a gear shaft (20) and also has at least one radial bearing (30) for rotary support of the gear shaft (20), the inner bearing ring (301) of the radial bearing being fixed on the gear shaft (20) and the outer bearing ring (302) of the radial bearing being fixed in a bearing box (31) disposed in the housing (10), in each case being fixed axially nondisplaceably. For simple assembly of the gt (15) without tools, the outer bearing ring (302) of the radial bearing (30) rests with a sliding seat in the bearing box (31) and is fixed by means of a clamping bracket (32) fixed to the bearing box (31).

Abstract: The invention relates to a pneumatic spring percussion mechanism comprising a driving piston moving back and forth in a housing of the percussion mechanism and a percussion piston, wherein a pneumatic spring is configured between the driving piston and the percussion piston. The movement of the driving piston can be transmitted to a percussion piston by means of said pneumatic spring. The driving piston can be driven by an electric linear motor and is connected to an aromatic of the linear motor, forming a single piece therewith. This arrangement makes it possible to eliminate the use of a conventional rotary motor and a crank mechanism to drive the driving piston.

Abstract: An impact device for a rock drill. The rock drill includes a tool and a mechanism for delivering a stress pulse to the tool. That mechanism includes an impact element supported to a frame of the drill, and a mechanism for subjecting the impact element to stress and thereafter releasing the impact element suddenly from the stress, whereupon stored stress energy in the impact element is discharged in the form of a stress pulse directed at the tool.

Abstract: A hammer drill is equipped with a connector shaft, which is rotationally driven by a motor, a spindle that transmits the rotation through a connector shaft, and a percussive impact impact mechanism that applies a percussive force in the axial direction to a drill bit held by the spindle through performing a reciprocating motion, in the axial direction, relative to a spindle that receives the rotation of the connector shaft through a motion converter mechanism. The hammer drill is provided with a percussive force converter from the percussive impact impact mechanism by changing the speed reduction ratio between the motor and the connector shaft. This makes it possible to adjust the percussive force according to the drill bit used.

Abstract: An electrical hand-held power tool for at least partially percussive driving of a tool (1) along a striking axis (A) and including a striking mechanism (2) having a striker (3) for generating striking forces on the anterior arranged tool (1) and a housing (5) enclosing the striking mechanism (2) and having a handle (6) affixed thereto, with the striker (3) being formed as a high-energy piezo actor connected with a voltage pulse generating unit (7), and rearwardly affixed to the housing (5).

Abstract: An electrically powered hammer comprises a housing, a spindle, a piston reciprocatingly mounted within the spindle, a wobble drive arrangement reciprocatingly connected to the piston, and a trunnion arrangement including a cross bolt is driving engaged between the wobble drive arrangement and the piston. The piston includes a pair of piston arms and a protrusion so that the first piston arm and the protrusion define a first recess and the second piston arm and the protrusion define a second recess, and each of the recesses is shaped so as to support a wear reducing washer in an assembled position. When assembled, each washer fits around the cross bolt in a region adjacent the inwardly facing face of the associated piston arm so as to reduce wear between the cross bolt and the piston arms.

Abstract: A device for switching operating modes for an at least partially rotational and percussive hand tool machine having an overload clutch, which is arranged between a hollow driving guide cylinder (3) containing an axially striking impact piston (2) and a rotating, driving crown gear (4) on the guide cylinder (3) and which can be switched into different operating modes using an externally manually switchable, axially displaceable switching member, wherein at least one operating mode is rotationally driven, wherein the axially displaceable switching member engages rotationally form-lockingly into a freely rotational coupling ring (6) of the overload clutch mounted relative to the guide cylinder (3).

Abstract: A hammer drill (1) includes a lock plate (35) forward of a boss sleeve (13) and a swash bearing (14) which cooperates with the boss sleeve to convert the rotation of an intermediate shaft (5) on which the boss sleeve is mounted. The lock plate is mounted on the boss sleeve and selectively engages claws (23) of the boss sleeve (13) in a manner that permits its integral rotation with and axial slide with respect to the boss sleeve. The lock plate is additionally biased in the forward direction by a coil spring (38) so that when a clutch (19) is shifted forward in a drill mode, the lock plate also moves forward into engagement with a stopper (39) secured to an inner housing (4), preventing inadvertent rotation of the boss sleeve.

Abstract: The invention is based on a hand power tool, in particular a drill- and/or chipping hammer, comprising a striking mechanism (10) that has a drivable pot-type piston (12) with at least one idle opening (14). It is proposed that the idle opening (14) is capable of being closed via a controllable, separate closing element (16).

Abstract: An electrically powered hammer comprising a hollow spindle within which spindle is reciprocatingly mounted a piston, a ram, a beatpiece having an increased external diameter mid-portion and located within the spindle between the ram and the tool or bit, a two part sleeve arrangement located within the spindle and including an increased internal diameter mid-portion for receiving the increased external diameter portion of the beatpiece and a reduced internal diameter forward and rearward portion for guiding the forward and rearward ends respectively of the beatpiece and where the sleeve arrangement includes a forward sleeve and a rearward sleeve which are both guided with tight radial tolerances and with a slight axial play within and by the spindle and the forward axial movement of the forward sleeve is limited by a reduced diameter portion of the spindle and the forward axial movement of the rearward sleeve is limited by the forward sleeve.