Abstract: In an electric hammer, ridges are provided in an outer surface of a barrel, grooves are provided in an inner surface of a front cover, and rotation of the front cover with respect to the barrel is prevented by fitting the ridges in the grooves. A flange, which is latched on a stepped portion provided in front of the ridges and the grooves in the inner surface of the front cover, is provided in a peripheral edge of a lock ring, and forward movement of the front cover is restricted by latching the flange on the stepped portion.

Abstract: An electric boring tool comprises an electric motor, a switch trigger, a tip tool driven by driving force of the electric motor, a power transmission mechanism for transmitting the driving force of the electric motor to the tip tool as rotational force and/or hammer force, and a motor control unit for controlling speed of the electric motor in response to an extent of pulling of the switch trigger. The motor control unit subjects the electric motor to low speed control after the electric motor is started up, and controls the speed of the electric motor in response to the extent of pulling of the switch trigger when the load current of the electric motor is set value or greater during the low speed control.

Abstract: A drill includes a housing and a motor coupled to an output member by a transmission. The transmission can selectively couple the output member to an output spindle through a low speed output gear or a high speed output gear for rotating the output spindle at a first speed or a second speed, respectively. Alternatively or additionally, a low speed mode can be provided by actuating an electronic switch that limits the speed of the motor. A rotatably fixed hammer member and a rotatable hammer member can be mounted around the output spindle. A mode collar can be rotatably mounted on the housing and around the output member for movement to positions that correspond to various mode of operation, including a low speed mode, a high speed mode, and a hammer-drilling mode. In the hammer-drilling mode, the transmission operates in the high speed mode.

Abstract: A rotary impact tool includes a drive shaft rotationally driven by a rotational drive power source, a hammer arranged around the drive shaft, a ball engaging with a cam groove formed on the outer circumferential surface of the drive shaft and a cam groove formed on the inner circumferential surface of the hammer, an anvil engageable with the hammer along a rotational direction and a spring for biasing the hammer toward the anvil. The hammer is designed to rotate along a rotational locus decided by the cam groove of the drive shaft and the cam groove of the hammer. The rotational locus of the hammer as seen in a development view describes a curve in which the lead angle of the rotational locus varies continuously with the change in hammer rotation angle.

Abstract: A hand-held electric tool having a housing, a machine core, and a working head disposed on the housing is further provided with a manual hammer component. The manual hammer component is usable to manually strike an object, such as a nail. The working head is disposed at one side of the front end of the housing and the manual hammer component is disposed at the other side of the front end of the housing and opposite to the working head.

Abstract: A percussion mechanism that has a motor, a drive piston which can be moved to and fro in a guide cylinder by the motor, and a percussion piston. A coupling device is active between the drive piston and the percussion piston, via which coupling device the movement of the drive piston is transmitted to the percussion piston. The motor can be configured as a reluctance motor or as a synchronous motor. The motor can be actuable in such a way that different rotational speeds of the rotor can be generated within a percussion cycle and/or from percussion cycle to percussion cycle.

Abstract: An impact wrench includes a housing, a rotation motor, an output shaft, and an impact mechanism including an inertia drive member with an impact chamber, a drive socket coupling the drive member to the motor, and anvil formed integral with an output shaft and extending into the impact chamber, and a coupling member arranged to transfer kinetic energy from the drive member to the anvil, a lubricant provided in the impact chamber, and barrier forming cover element mounted on the drive member to seal off the impact chamber and prevent lubricant from being expelled from the impact chamber at rotation of the drive member.

Abstract: A device for impacting a fastener in one embodiment includes a lever arm pivotable between a first position whereat a flywheel is spaced apart from a drive mechanism and a second position whereat the flywheel can contact the drive mechanism, a lever arm solenoid for pivoting the lever arm between the first position and the second position, a drive mechanism sensor for generating a position signal indicative of the position of the drive mechanism, a timer for generating a timing signal, a memory including program instructions, and a processor operably connected to the memory for executing the program instructions to (i) energize the solenoid to pivot the lever arm to the second position, (ii) de-energize the solenoid based upon the position signal, and (iii) de-energize the solenoid based upon the timing signal.

Abstract: A device for impacting a fastener in one embodiment includes a drive mechanism, a flywheel pivotable between a first flywheel position whereat the flywheel is not in contact with the drive mechanism and a second flywheel position whereat the flywheel contacts the drive mechanism, a motor operably connected to the flywheel, a trigger movable between a first trigger position and a second trigger position, and a WCE assembly movable between a first WCE position and a second WCE position, the WCE assembly configured such that (i) when the trigger is in the first trigger position and the WCE assembly is in the first WCE position, the WCE assembly mechanically engages the trigger to preclude movement of the trigger out of the first position, and (ii) when the WCE assembly is in the second WCE assembly position, the WCE assembly does not mechanically engage the trigger.

Abstract: The invention relates to a striking mechanism of a handheld electric power tool, in particular a percussion drill and/or percussion hammer, having a hammer cylinder, a piston mounted with a guide section inside the hammer cylinder in a longitudinally displaceable manner, and a piston outer guide on which a guide area of the piston is guided in a longitudinally displaceable manner. A piston end located outside the hammer cylinder comprises an overlap for overlapping an end area of the hammer cylinder, and the guide area at least partially belongs to the overlap or is affixed there.

Abstract: A multi-mode drill can include a transmission to transfer torque from an output member of a motor to an output spindle. A transmission housing encloses the transmission in an interior cavity formed by a gear case shell and a cover plate. The cover plate can be coupled to the outer shell via screws. A static shift rod can be supported at one end by the cover plate. A shift bracket can be mounted on the shift rod and biased to a mode position by a biasing member exerting a force between the shift bracket and the cover plate. A shift pin can be supported adjacent one end by the cover plate and biased to a mode position by a biasing member exerting a force between the shift pin and the cover plate. A spindle biasing member can bias the output spindle against the cover plate. The shift pin can actuate an electronic switch. A motor housing can be coupled to the transmission housing with fasteners so that the cover fasteners are not accessible.

Abstract: An impact tool for simultaneously providing a rotational force and an impact force to an object has an output shaft rotated by a motor, hammer for intermittently providing an impact force to the output shaft, hammer holder for movably holding the hammer, and an impact force generator for generating the impact force from an output of the motor. An air chamber is formed between the hammer and the hammer holder such that a volume of the air chamber is variable in response to a position of the hammer relative to the hammer holder. In addition, the hammer receives a bias force generated in a direction toward the output shaft by a biasing device. This bias force effectively increases the impact force in cooperation with an air pressure caused by a volume change of the air chamber.

Abstract: An impact driver for driving elongate objects into a body has, a chassis, a ram supported by the chassis in a manner allowing rectilinear movement of the ram relative to the chassis between two limits, and a linear induction motor. The linear induction motor has a stator mounted to the chassis and positioned to operatively interact with a linear induction motor reaction member being of a conductive metal material. The reaction member is carried by the ram in a manner to allow the ram to oscillate between the two limits by the stator of the linear induction motor. A first limit being a retracted position and a second limit being an impact position to which the ram is accelerated from the retracted condition by the stator and at which the ram imparts an impact force on the elongate object in the elongate direction thereof.

Abstract: A drill includes a housing with a motor coupled to an output spindle via a transmission. A mode collar can be rotatably mounted on the housing for movement that corresponds to different modes of operation. The mode collar can be coupled to an electronic switch to operate a movable member thereof. The coupling can include a switch housing including a slide member, an actuation spring member and a return spring member. The mode collar can have a cam surface and a cam follower in the form of a shift pin that moves the slide member, causing actuation of the switch. The actuation spring member provides a biasing force that is sufficient to overcome a biasing force of a switch spring member to move the movable member into the actuated position. The mode collar can also enable and disable contact between a fixed hammer member and a movable hammer member mounted around the output spindle.

Abstract: A nailer device has a housing containing a motor and a striking device arranged in a compact manner. A transmission mechanism is mounted in the housing for translating the rotating motions of the motor into the periodic impact motions upon the striking device. The transmission mechanism includes an impact assembly which imparts the periodic impact motions upon the striking device.

Abstract: An electric hammer comprising a hammer bit performing hammering work on a work, a drive motor, a hammering piece driven by the drive motor to apply a hammering force to the hammer bit, and a mechanism for damping vibration generated during hammering. The damping performance of the electric hammer is enhanced by causing the driving amount applied to the damping mechanism to vary between a first mode where the damping mechanism generates vibration of the hammer bit subjected to an external force from the work during the load driving time and thereby optimizes the damping and a second mode where the damping mechanism generates vibration corresponding to the vibration of the hammer bit not subjected to an external force from the work during the no-land driving time and optimizes damping.

Abstract: A shift bracket can be mounted on a shift rod for movement between a first, high-speed drilling mode and a second, low-speed drilling mode. Cooperating shift lock surfaces can be associated with the shift bracket and the shift rod, respectively. For example, a groove in the can create a shift lock surface on the shift rod. The shift bracket can be moved into a locked configuration where the cooperating shift lock surfaces can engage each other preventing movement of the bracket out of the high-speed drilling mode. The hammer mode can correspond to the high-speed drilling mode, but not to the low-speed drilling mode. A spring member can bias the bracket toward the locked position. An actuation member can be coupled to the shift bracket to overcome the biasing member and to rotate or perpendicularly move the bracket into an unlocked position. The actuation member can also move the shift member from the first mode to the second mode.

Abstract: A drill includes a housing and a motor coupled to an output member by a transmission. The transmission can selectively couple the output member to an output spindle through a low speed output gear or a high speed output gear for rotating the output spindle at a first speed or a second speed, respectively. Alternatively or additionally, a low speed mode can be provided by actuating an electronic switch that limits the speed of the motor. A rotatably fixed hammer member and a rotatable hammer member can be mounted around the output spindle. A mode collar can be rotatably mounted on the housing and around the output member for movement to positions that correspond to various mode of operation, including a low speed mode, a high speed mode, and a hammer-drilling mode. In the hammer-drilling mode, the transmission operates in the high speed mode.

Abstract: A tool is disclosed for driving a slide under a wedge within a slot of an armature or field of a dynamoelectric machine. The tool comprises a frame including a pair of elongated rail members; a force application block located between the rail members; a drive connected to the frame, substantially intermediate opposite ends of the frame; a lead screw threadably engaged at one end with the force application block and connected at an opposite end to the drive such that the drive rotates the lead screw when actuated. Rotation of the lead screw causes axial movement of the force application block. The armature or field includes a core, and this core may have one or more vent slots for facilitating ventilation of the armature or field. A slot plate for locating the tool relative to the slide is present, and a portion of the slot plate extends into one or more vent slots. The slot plate establishes a reaction point for forces applied by the force application block to the stator slide.

Abstract: A power tool cooling system comprises a cooling fan disposed on a motor in a position between the upper field coil and the lower commutator. A transmission housing encapsulates the transmission mechanism. During operation, the fan is driven by the motor and draws air axially through the motor and expels the air radially outwardly through holes in the outer housing of the motor. This causes air to be drawn in through the air vents formed on the top of a tool housing, in the side of the housing and between the housing and a battery pack. The cool air flows outside of the transmission housing, but inside the tool housing such that air does not pass through the transmission mechanism. A plurality of motor openings are also formed in the outer housing of the motor to enable cool air to pass into the motor to cool the motor.

Abstract: A power tool has a mechanism for ejecting a battery pack which includes a receiving frame which defines a cavity to receive a battery pack. A receiving member is adjacent the cavity. The receiving member meshes with a member on the battery pack to hold the battery pack in the cavity. A biasing member is in the cavity adjacent the receiving member. The biasing member ejects the battery pack from the ejecting mechanism. A member retains the biasing member in the cavity. The member guides a portion of the battery pack meshing with the receiving member into contact with the biasing member such that when the battery pack is locked onto the frame, the biasing member is in a compressed condition and when the battery pack is an unlocked position, the biasing member ejects the battery pack from the frame.

Abstract: A hammer drill has an electric drive motor having a motor shaft and a tool shaft driven in rotation by the electric drive motor. A hammer action is provided. The tool shaft is driven by a first single-stage gear unit directly by the motor shaft of the electric drive motor. The hammer action is driven by a second single-stage gear unit directly by the motor shaft of the electric drive motor.

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 though an unnecessary driving mode position. Therefore, ease of operation in mode change can be enhanced.

Abstract: A shock-absorbing element is disposed frontward of an interjacent element within a housing of an impact tool, and a washer is disposed rearward of and adjacent to the shock-absorbing element. The interjacent element is configured to come in contact with the washer when the interjacent element is caused to advance by an impactor's strike under no-load conditions. A sleeve disposed rearward of and adjacent to the washer is configured to position the shock-absorbing element and the washer, and to allow the interjacent element to move rearward and frontward inside the sleeve.

Abstract: It is an object of the invention to provide a technique that contributes to further improvement of an impact tool. A representative impact tool includes a motor, a tool body that houses the motor, a dynamic vibration reducer and a driving mechanism part that is driven by the motor and forcibly drives the dynamic vibration reducer by applying an external force other than vibration of the tool body to the dynamic vibration reducer, during hammering operation. At least one of the dynamic vibration reducer and the driving mechanism part is mounted to the tool body in a form of an assembly into which at least one of a plurality of component parts forming the dynamic vibration reducer and a plurality of component parts forming the driving mechanism part are assembled in advance.

Abstract: The present invention is an operatively connectable hammer tool that is sole-operated by an electric-hammer. The said invention is to forcibly guide the drive cleat in the joining of two rectangular sheet metal ducts. Wherein the slot having parallel sides with horizontal restrictions operatively connectable to an electric hammer as means of forcibly guiding the drive-cleat, Where as the slot having two parallel sides with cross-drilled openings as means to connect the said invention to the said drive cleat, using vibrations energized by an electric hammer to hook and drag, removing the said drive cleat.

Abstract: A novel impact wrench is provided herein, which allows a user to set a target torque level, show the torque level in a display, and automatically stops the motor when the target torque level is reached. The impact wrench is constructed such that its electrical current would be at a maximum when it engages an impact operation, and at a minimum after the impact operation. The electrical current exhibits a periodic pulse and the periodic pulse is used to calculate the number of times of impacts. The torque level of the impact wrench could then be determined by the number of times of impacts.

Abstract: An electric hand tool device, in particular, a percussion drill or a drill hammer, comprises a spindle (10) that can be driven by a drive motor and cooperates at one end (12) with a tool support, and a percussion element (24) for axially moving the spindle (10) in a percussion position, wherein an adjusting element (42) is provided for adjusting the spindle (10) between the percussion position and a rotary position, the adjusting element (42) comprising a switch ring (44) which is disposed about the spindle (10) and has cam configurations (46,48) on both end faces thereof, wherein one of the cam configurations (46) can engage in a corresponding cam configuration (52) which is fixed to the housing through turning the switch ring (44), and the second cam configuration (48) can be brought into engagement with a corresponding cam configuration (60) of a pressure piece (54) which can be axially moved relative to the housing (16), in order to adjust the percussion element (42) to a percussion position.

Abstract: A multi-mode drill can include a transmission to transfer torque from an output member of a motor to an output spindle. A transmission housing encloses the transmission in an interior cavity formed by a gear case shell and a cover plate. The cover plate can be coupled to the outer shell via screws. A static shift rod can be supported at one end by the cover plate. A shift bracket can be mounted on the shift rod and biased to a mode position by a biasing member exerting a force between the shift bracket and the cover plate. A shift pin can be supported adjacent one end by the cover plate and biased to a mode position by a biasing member exerting a force between the shift pin and the cover plate. A spindle biasing member can bias the output spindle against the cover plate. The shift pin can actuate an electronic switch. A motor housing can be coupled to the transmission housing with fasteners so that the cover fasteners are not accessible.

Abstract: A drill includes a housing and a motor coupled to an output member by a transmission. The transmission can selectively couple the output member to an output spindle through a low speed output gear or a high speed output gear for rotating the output spindle at a first speed or a second speed, respectively. Alternatively or additionally, a low speed mode can be provided by actuating an electronic switch that limits the speed of the motor. A rotatably fixed hammer member and a rotatable hammer member can be mounted around the output spindle. A mode collar can be rotatably mounted on the, housing and around the output member for movement to positions that correspond to various mode of operation, including a low speed mode, a high speed mode, and a hammer-drilling mode. In the hammer-drilling mode, the transmission operates in the high speed mode.

Abstract: A shift bracket can be mounted on a shift rod for movement between a first, high-speed drilling mode and a second, low-speed drilling mode. Cooperating shift lock surfaces can be associated with the shift bracket and the shift rod, respectively. For example, a groove in the can create a shift lock surface on the shift rod. The shift bracket can be moved into a locked configuration where the cooperating shift lock surfaces can engage each other preventing movement of the bracket out of the high-speed drilling mode. The hammer mode can correspond to the high-speed drilling mode, but not to the low-speed drilling mode. A spring member can bias the bracket toward the locked position. An actuation member can be coupled to the shift bracket to overcome the biasing member and to rotate or perpendicularly move the bracket into an unlocked position. The actuation member can also move the shift member from the first mode to the second mode.

Abstract: A hand-held drive-in tool for driving fastening elements (60) in a workpiece (U) includes a drive-in ram (13) displaceable in a guide (12), a spring (31) for driving the drive-in ram (13), a tensioning device (70) for loading the driving spring (31), a locking device (50) for retaining, in its locking position (54), the driving spring (31) in its loaded position thereof (33), and a sliding nut (78) supported on a threaded spindle (76), which is rotatable by the motor (71) of the tensioning device (70), without a possibility of rotation thereabout but with a possibility of an axial displacement therealong, the sliding nut (78) being axially displaceable, upon actuation of the motor (71) of the tensioning device (70) by a control unit (23) of the drive-in tool (10), from the first end position (83) to the second end position (84) for displacing the driving spring (31) into the loading position (33) of the driving spring (33), and being subsequently displaceable from its second end position (84) into the first e

Abstract: A nail gun includes a power coil for moving a plunger in two opposed directions. The plunger is first moved away from a nail, and force from this movement is stored in a force storage mechanism. The plunger is then driven by the coil in an opposed direction, and the force stored within the forced storage mechanism is released, such that the released force and the power force from the coil are combined to drive a nail into a work piece.

Abstract: A drive-in tool for driving in fastening elements includes a driving ram (13) displaceable in a guide (12) and driven by a drive flywheel (32), a drive unit (30) having an electric motor (31) for rotating the drive flywheel (32), a drive coupling (35) for connecting a coupling section (15) of the driving ram (13) with the at least one drive flywheel (32), and an acceleration device (40) for accelerating the driving ram (13), together with the coupling section (15) in a direction of the drive flywheel (32).

Abstract: An electric hammer comprising a hammer bit (313) performing hammering work on a work, a drive motor, a hammering piece (334) driven by the drive motor to apply a hammering force to the hammer bit, and a mechanism (371) for damping vibration generated during hammering. The damping performance of the electric hammer is enhanced by causing the driving amount applied to the damping mechanism (371) to vary between a first mode where the damping mechanism (371) generates vibration of the hammer bit (313) subjected to an external force from the work during the load driving time and thereby optimizes the damping and a second mode where the damping mechanism (371) generates vibration corresponding to the vibration of the hammer bit (313) not subjected to an external force from the work during the no-land driving time and optimizes damping.

Abstract: The invention is based on a power hand tool, in particular a hammer drill and/or hammer chisel, with a percussion unit (10), which comprises a tumble bearing unit (12) with a tumble body (14) and also a piston (16). It is proposed that the power hand tool comprises at least two bearing locations (18, 20; 22, 24) arranged in parallel in the force of flux, by means of which the tumble body (14) is coupled to the piston (16).

Abstract: A boring and/or percussion hammer comprises an electrodynamic linear drive and a pneumatically damped percussion mechanism which is provided with a drive piston driven by the linear drive during the reciprocating movement thereof, an impact piston and a pneumatic spring arranged between the drive and impact pistons. An air-supply device comprises a pumping element, which is linearly forth and back movable for generating airflow. The pumping element is connected to the drive piston in such a way that the movement thereof is transmitted to said pumping element, thereby the cooling air is transported by an air channel for cooling heat generated elements.

Abstract: A method of controlling a single-phase linear motor (1) for driving a striking mechanism (2) with a loose coupling (4) between a runner (5) of the linear motor (1) and a striker (6) of the striking mechanism (2) has, within a striking period in which exactly one force impact (K) of the striker (6) is carried out on a tool (8) or an anvil (7), a pull phase (Z) in which the loose coupling (4) contacts a runner-side contact surface (KL) with a one-sided constrained contact and a push phase (D) in which the loose coupling (4) contacts a striker-side contact surface (KS) with a one-sided constrained contact, and a change phase (W) provided between the pull phase (Z) and the push phase (D) in which the one-sided constrained contact changes between the two contact surfaces (KL-KS) along a contactless reciprocating gap (S) in that the runner (5) releases the one-sided constrained contact with one contact surface (KL/KS) in a regulated manner and produces the one-sided constrained contact with the other contact surfac

Abstract: A drive-in tool for driving in fastening elements includes a driving ram (13) displaceable in a guide (12) and driven by a drive flywheel (32), a drive unit (30) having an electric motor (31) for rotating the drive flywheel (32), a drive coupling (35) for connecting a coupling section (15) of the driving ram (13) with the at least one drive flywheel (32), and an acceleration device (40) for accelerating the driving ram (13), together with the coupling section (15) in a direction of the drive flywheel (32).

Abstract: A hammer drill comprising: a motor; a drive transmission capable of operating in at in at least a rotary mode and a reciprocating mode; a mode change mechanism; a switch which, when closed, provides power to the motor; and a mechanical lock-on mechanism which, when locked mechanically holds the switch closed to maintain the power to the motor. Additionally, the hammer drill includes a first sensor, which indicates the mode of operation of drive transmission; and a second sensor which indicates whether the lock-on mechanism is locked; and a controller which is capable of interfering with the operation of the motor, when the controller detects that the drive transmission is in the rotary mode of operation and the lock-on mechanism has been locked.

Abstract: It is an object of the present invention to provide an effective technique to alleviate vibration in the electric hammer drill. According to the invention, representative electric hammer drill is provided with a body, a motor, a striker, a cylinder, first and second power transmitting mechanisms, a power switching mechanism, a mode changing mechanism, and a coupling mechanism. The mode changing mechanism is disposed on the upper surface of the body and can change between a hammer-drill mode and a hammer mode. The coupling mechanism is disposed between the mode changing mechanism and the power switching mechanism. The coupling mechanism extends along the peripheral surface of the cylinder and transmits the mode changing movement of the mode changing mechanism to the power switching mechanism by moving in the longitudinal direction of the cylinder.

Abstract: A percussion power tool includes a motor (6) located in the tool-housing (4) for driving the output member (12) and the percussion mechanism (10), a chuck (20) for receiving a working tool (22), a locking mechanism (24) for securing the chuck (20) on the output member (12) and including at least one locking member (26) which provides in a locking position thereof, for a formlocking connection between a connection member (30) of the chuck (20) and the output member (12), an adjusting sleeve (34) that prevents, in its blocking position, a radial displacement of the at least one locking member (26) from the locking position and a damping member (56) provided between the output member (12) and the connection member (30) and acting in the axial direction.

Abstract: A power tool (1) having a striking means (5), by which a percussive tool (2) that can be driven at least partially along an axis (A) struck directly and having a flushing bore (4) extending at least partially longitudinally through a tool shank (3), and having a flushing head (6) having a radially inwardly open transverse bore hole (8) connected in a flow-through fashion with a fluid channel (7). The flushing head (6) has at least one hollow cylindrical sleeve-like guide surface (9), which is fitted for an insertion end (10) of the striking tool (2). The striking means (5) sealed by a seal (11a, 11b) is cup-like. The striking means (5) is moveably guided and made fluid tight by the seal (11a, 11b) to embrace the machine-side part of the insertion end (10) having the machine-side open flushing bore (4).

Abstract: A pneumatic grinder with improved muffling structure primarily comprises a driving portion, a grinding wheel fixing portion provided at one end of the driving portion, a first housing connected to the other end of the driving portion by means of a combining portion, a second housing mounted onto the first housing, and a plurality of first and second exhaust openings arranged in staggered fashion respectively on the first and second housings. Said structure allows the pneumatic grinder to discharge waste air through foresaid two layers of exhaust openings in staggered fashion arranged in order to reduce noise during air exhaust.

Abstract: A pulse torque generator utilizing a magnetic coupling, and an electric power tool provided with the pulse torque generator. The pulse torque generator includes an input shaft extending in its axial direction and having a hollow section providing a hollow space, and an output shaft rotatably provided in the hollow space. A magnetic fluid is encapsulated in a hollow space between the input shaft and output shaft. A magnetic field generating unit is disposed, and magnetic segments are provided in the input shaft. A magnetic fluid provides a magnetic fluid bridge bridging between the input shaft and the output shaft each time the magnetic segment is brought into confrontation with the magnetic field generating unit.

Abstract: It is an object of the present invention to provide a vibration reducing technique caused by air pressure fluctuations within a power tool. According to the present invention, a representative power tool may comprise a driving motor, a driver and a tool bit. The driving motor drives the driver to cyclically reciprocate. The tool bit is linearly driven by utilizing the pressure of air within the power tool. The air may be compressed by the reciprocating movement of the driver. The power tool changes the rotational speed of the driving motor in the cycle of the reciprocating movement of the driver so that vibration caused in the power tool can be alleviated.

Abstract: An impact mechanism for a hammer drill, which has a housing and a drill bit protruding outside the housing, is provided. The mechanism includes firstly an impact platform within the housing; the impact platform is in connection with the drill bit for receiving impact forces and for transferring the impact forces to the drill bit. The mechanism also has a plurality of cams within the housing, and the plurality of cams are angularly spaced apart and arranged about an axis of rotation. The mechanism further includes a plurality of hammers placed within the housing and interactable with both the impact platform and the plurality of cams. The plurality of hammers are angularly spaced apart and arranged about the axis of rotation, and each hammer is capable of reciprocating along the axis for exerting the impact forces on the impact platform.

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 present invention to provide a reciprocating power tool having a further improved power transmission mechanism for converting a rotating output of a driving motor into linear motion in the axial direction of the tool bit. According to the present invention, a representative reciprocating power tool may comprise a tool bit, a driving motor, a power transmission mechanism. The power transmission mechanism converts a rotating output of the driving motor into linear motion in the axial direction of the tool bit. The power transmission mechanism includes an internal gear, a planetary gear and a power transmission pin. The internal gear is allowed to rotate by a predetermined degree in relation to a load applied to the tool bit. As the result of rotation of the internal gear, the relative position of the power transmission pin is changed with respect to the point of engagement between the internal gear and the planetary gear.

Abstract: The invention relates to a pneumatic percussive tool for a paving breaker and/or a hammer drill comprising a drive piston which is displaceable both backwards and forwards by a crankshaft and arranged in a percussion piston which is displaceable both backwards and forwards. A hollow chamber is connected to a compensating chamber by an idling air channel and embodied between the drive piston and the percussion piston in order to receive a pneumatic spring. A valve is arranged in the idling air channel, the opening and closing position thereof depending on the rotational speed of the crankshaft. If the rotational speed of the crankshaft falls below a predetermined value, the valve opens the connection between the hollow chamber and the compensating chamber so that a pneumatic spring can no longer be to embodied in the hollow chamber and the pneumatic percussion tool is placed in a idling position.