Abstract: It is an object of the invention to provide a technique for bringing a center of gravity of a battery-powered power tool closer to a working axis of a tool bit in the battery-powered power tool. The battery-powered power tool performs an operation by movement of a tool bit 119 in an axial direction of the tool bit. The power tool includes a battery 110, a motor 111 that is driven by power supply from the battery 110, a mechanical arrangement 113, 115, 117 that drives the tool bit 119 by rotative power transmitted from the motor 111, and a tool body 103 that houses the motor 111 and the mechanical arrangement 113, 115, 117 and has a front end region in which the tool bit 119 is disposed. A sum of weights of the motor 111 and the battery 110 is smaller than a weight of the mechanical arrangement 113, 115, 117.

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: In a handheld machine tool having a tool housing in which a gear unit is situated to transmit a torque generated by a drive motor to a drive spindle, to which drive spindle a spindle-locking device is assigned, the drive spindle has at least one radial depression in which at least one spindle cylinder assigned to the spindle-locking device is accommodated.

Abstract: A power tool includes a case; a motor installed within the case, the motor comprising a motor housing and a rotor with shaft; a gear train comprising a gear train housing and a speed reduction mechanism installed within the gear train housing and connected to the shaft of the motor. The motor housing and the gear train housing are integrally formed as a common housing and fixed relative to the case.

Abstract: A power tool with first and second housing portions, a powertrain, a mounting hub and a lock bar. The powertrain has an output member that extends from the second housing portion and which is movable relative to an output member axis. The mounting hub is fixedly coupled to one of the first and second housing portions. The lock bar is movably mounted to the other one of the first and second housing portions between a locked position and a first unlocked position. The lock bar cooperates with the mounting hub in the locked position to inhibit relative rotation between the first and second housing portions. Placement of the lock bar in the first unlocked position permits relative rotation between the first and second housing portions.

Abstract: A switchable planetary gearbox in a hand-held power tool includes multiple planet carriers having associated planet wheels, and is to be displaced between at least two gear ratios, such that the gear ratios are to be engaged via a displaceable switching ring gear. At least three planet carriers having associated planet wheels are provided axially behind one another, such that in a position fixed with respect to the housing, the switching ring gear is rotationally coupled to the planet wheels on the second-stage planet carrier and simultaneously to the planet wheels on the third-stage planet carrier.

Abstract: A pneumatic spanner structure includes a head body, a link bevel gear unit, a hit unit and a driving handle. A driving motor axle portion at an open end of the driving handle drives a motor link bevel gear post and a hit unit link bevel gear plate of the link bevel gear unit. The hit unit link bevel gear plate links the hit unit. The link bevel gear unit enhances and transmits the force to the hit unit. The hit unit applies the acting force on a workpiece. The hit unit doesn't need a buffer space for actuation and the force is indirect. The link bevel gear unit is a deceleration device to extend the service life of the whole structure. The output force is more powerful than the prior art, providing a stable and compact structure.

Abstract: A power tool includes a housing, an electric motor, a speed change mechanism, and a protrusion member. The housing defines therein a mechanism chamber. A lubricant is inserted in an interior of the mechanical chamber. The electric motor is accommodated in the housing. The speed change mechanism is disposed in the mechanism chamber and connected to the motor for shift-transmitting rotation of the motor. The protrusion member protrudes to the mechanism chamber from the housing in a protrusion direction. The protrusion member provides a communication passage that has one opening open at a leading end side of the protrusion member in the protrusion direction and another opening open to an exterior of the mechanical chamber. At least a part of the protrusion member provides the communication passage and is made from a resilient material.

Abstract: An electric power tool, in particular a drill/screwdriver, has a drive motor which is coupled via a gearbox to an output drive element. The gearbox has a plurality of gears. In particular, the drive motor is coupled to a drive spindle in which the torque generated by the drive motor is adjustable. The torque can be adjusted by a first, manually operated, adjusting device, and by a second, manually operated, adjusting device. The second adjusting device is configured to adjust the torque by selecting the gear of the gearbox. Both adjusting devices are operated by a common actuating element.

Abstract: A head structure of a pneumatic tool has an accommodation room in a pneumatic tool body. A driving gear and a transmission unit are pivoted in the accommodation room. The transmission unit includes a gear member having a transmission gear to mesh with the driving gear. The rear end of the gear member is provided with a gear rod. A bearing fitted on the gear rod is limited to a first limit portion at the distal end of the transmission gear. The gear rod is connected with a connection member which has a second connection portion to engage with the first connection portion. The connection member has a second limit portion adapted to limit another side of the bearing. The limit member is secured to the distal end of the accommodation room. The limit member is adapted to limit the bearing in the accommodation room.

Abstract: It is one kind of hand-held electric power tool with safety shift device, including housing assembly, motor, end cap of gear box, gear box, output shaft, final-stage rack wheel, final-stage pinion, gear pin roll, safety shift pin roll, gear knockout plate, gear synchronous spring, safety shift spring, safety push rod, stop pin, variable-speed pinion axis, variable-speed rack wheel, big bevel pinion, bevel pinion and grinding wheel shield. Among which, the gear pin roll and safety shift pin roll are installed within the gear box in parallel, the gear knockout plate is connected with final-stage rack wheel and final-stage pinion, the gear synchronous spring is installed on the gear pin roll while the safety shift spring is installed on the safety shift pin roll. This new practical hand-held electric power tool with safety shift device is characterized by low-speed gear automatic recovery function and the dangers of disoperation will be avoided, being safe and convenient.

Abstract: A pneumatic impact tool includes a housing, a power output unit, a transmission unit, and an oil seal assembly. The housing has first and second accommodating chambers, and first and second oil inlets in fluid communication with the first and second accommodating chambers, respectively, and permitting lubricating oil to be fed into the first and second accommodating chambers therethrough. The power output unit is centered at a Z-axis, and is disposed in the first accommodating chamber for power outputting. The transmission unit is centered at an X-axis, and is disposed in the second accommodating chamber for transmitting a power to the power output unit. The oil seal assembly prevents flow of the lubricating oil out of the first and second accommodating chambers.

Abstract: A technique that increases operability in changing the rotational speed of a spindle in a power tool. The rotational speed can be changed in three levels by utilizing a planetary gear mechanism. The third gear position is located in an intermediate position in the sliding direction of the speed changing part. The first speed change position is located on one side of the third speed change position. The second speed change position is located on the other side of the third speed change position. During operation, shifting between the first and third speeds can be done without going through the second speed each time. Further, shifting between the second and third speeds can be done without going through the first speed. Therefore, speed change shifting can be facilitated.

Abstract: A power tool having a housing assembly and a drive component that is housed in the housing assembly. The housing assembly has a first housing component, a second housing component, at least one set of mating conically-shaped features, and at least one fastener. Each set of mating conically-shaped features includes a first cone portion and a second cone portion. The first cone portion of each set of mating conically-shaped features is coupled to the first housing component and has a frusto-conically-shaped exterior surface. The second cone portion of each set of mating conically-shaped features is coupled to the second housing component and has a frusto-conically-shaped interior surface that is engaged with the frusto-conically-shaped exterior surface of an associated first cone portion. Each fastener is received through an associated pair of the first and second cone portions and is threadably engaged to one of the first and second housing components.

Abstract: An electric driver (1) as a power tool comprises a motor (2) which actuates a tool bit (100). The electric driver (1) has a first planetary gear mechanism (30), a second planetary gear mechanism (40), and a regulation member which regulate a second outer gear (43) to rotate. The regulation member includes an outer gear engaging member (50) and a deformable member (51) which is fixedly connected to the outer gear engaging member (50). The deformable member (51) extends in a direction in which a rotational axis of the first and the second planetary gear mechanism (30, 40) extends. A controller (61) is adapted to measure rotation torque based on displacement of the deformable member (51) via a strain gauge (55) which is attached on the deformable member (51).

Abstract: In a speed change device of an electrical power tool, a reset arm is provided separately from a switch lever, which arm is operated by a reset motor. Due to tilting motion of the reset arm, a lock ring can be returned to an unlocking position in which a second stage internal gear can be rotated, so that the speed change device can be rest to a high speed low torque mode.

Abstract: A power tool for cutting a workpiece including a casing, an auxiliary handle assembly extending from the casing, a motor disposed at least partially in the casing, and a drive transmission operably coupled to the motor. The drive transmission outputs a driving force in response to an input from the motor. A spindle locking mechanism is provided that is selectively positionable between a retracted position spaced apart from the drive transmission and a locked position engaging the drive transmission. The spindle lock mechanism thereby prevents rotation of the drive transmission in response to actuation of a pad member. The pad member can be positioned adjacent to the auxiliary handle to permit single-handed holding of the power tool and actuation of the pad member.

Abstract: The invention relates to a hand-held power tool for predominantly percussively driven tool attachments, in particular hammer drills and/or chisel-action hammers. The power tool includes a percussion axis and an intermediate shaft that is parallel to the percussion axis in which a first stroke generating device having a first stroke element for a percussion drive is arranged in or on the intermediate shaft and can be driven by the intermediate shaft. Additionally, at least one other second stroke generating device having at least one second stroke element is provided for driving a counter oscillator. A phase displacement that is different from zero and that is unequal to 180° takes place between a movement of the first stroke element and a movement of at least one second stroke element.

Abstract: A power tool having a drive component and a housing. In one form, the drive component can be a transmission having a planetary stage with planet gears rotatably mounted on pins of a planet carrier. The pins are spaced circumferentially around the planet carrier such that each pair of adjacent pins is spaced apart by a spacing angle. At least two different spacing angles are employed. In another form, the drive component is selected from at least one of a motor, a transmission and a clutch and the housing is configured with first and second housing components and at least one set of mating conically-shaped features that can cooperate to align the housing components to an axis.

Abstract: A plurality of components of a power tool are coupled to each other to form a component assembly. Positioning members are disposed within a housing body and resiliently support the component assembly from opposite sides in an axial direction.

Abstract: A saw assembly includes a housing, a motor, a worm gear, and a drive member. The housing defines an interior space. The motor is positioned in the housing and has a motor shaft, the motor being configured to rotate the motor shaft about a first axis. The worm gear is positioned in the housing and has a worm gear shaft. Rotation of the motor shaft causes rotation of the worm gear shaft. The drive member is operatively coupled to the worm gear. Rotation of the worm gear shaft causes movement of the drive member in a repeating pattern. The worm gear shaft includes a bore structure defining a blind bore and an opening leading to the blind bore. The bore structure defines a set of internal threads that are spaced apart from the opening. The motor shaft includes a set of external threads.

Abstract: The present invention provides a handheld driver having a housing with a handle and a trigger that drives a set of gears to rotate a shaft having a fitting for a socket, screwdriver bit or drill bit.

Abstract: The present disclosure provides an apparatus comprising a frame supporting a motor and a gearbox, wherein the motor and the gearbox are connected to one another via coupling and further wherein the gearbox is oriented ninety (90) degrees from its normal operating orientation; and a bit assembly, the bit assembly comprising a shaft, having a first end and a second end, wherein the first end is attached to the gearbox via a gearbox output flange, a main bit assembly further comprising an upper cutting blade and a lower cutting blade attached to the shaft, wherein the lower cutting blade is located closer to the second end of the shaft than the upper cutting blade, an adjustable depth cutting guide attached to a bottom portion of the upper cutting blade, and a lateral cutting blade attached at the far end of the upper cutting blade; and a guide bit assembly wherein the apparatus is attachable to a self-propelled vehicle.

Abstract: The present invention provides multi-directional oscillation from a rotational source, by receiving a rotational motion, converting the rotational motion to a first oscillating motion, converting the first oscillating motion to a second oscillating motion that is normal to the first oscillating motion and transferring the first oscillating motion and the second oscillating motion to a working element.

Abstract: A grinder as a power tool has a torque limiter. The torque limiter includes a second bevel gear; a spindle; a flange to which the rotation of the second bevel gear is transmitted, and a plurality of balls which are disposed between the second bevel gear and the flange. The ball is positioned at a first region and the second bevel gear, the ball and the flange rotate integrally thereby the rotation is transmitted to the flange. In a state that a torque exerted on the spindle exceeding the predetermined threshold, a relative rotation between the second bevel gear and the flange is occurred and the ball moves from the first region to the second region while rolling by means of the relative rotation. Therefore, the transmission of the rotation from the second bevel gear to the flange is regulated, and the torque exerted on the spindle is regulated.

Abstract: A power tool that includes a housing, a trigger switch that is mounted to the housing, a tool output member and a motor and transmission assembly. The housing defines a handle. The motor and transmission assembly is coupled to the housing and is configured to drive the tool output member. The motor and transmission assembly include a motor, which is electrically coupled to the trigger switch, and a transmission having a transmission input member, which is drivingly coupled to the motor, and a transmission output member that is drivingly coupled to the tool output member. The motor and transmission are packaged in the housing in a manner that is extremely compact.

Abstract: A rotary impact tool includes a drive power source for producing rotational power, a drive shaft driven by the rotational power supplied from the drive power source, an output shaft operatively connected to the drive shaft for receiving the rotational power, an impact mechanism operatively couplable with the drive shaft. The rotary impact tool further includes a changeover unit for changing over an impact mode in which the impact mechanism is operated and a drill driver mode in which the rotational power produced by the drive power source is transferred to the output shaft without operating the impact mechanism and a multi-stage speed reduction mechanism for transferring the rotational power produced by the drive power source to the output shaft through the drive shaft at variable speeds in at least three speed modes including a low speed mode, a middle speed mode and a high speed mode.

Abstract: A power tool is provided for turning the screw collars 7 of falsework without the requirement of having to use spanners with long torque bars and without having to strike those torque bars with hammers or sledgehammers in order to exert the necessary torque on the collars 7. The tool is in two parts. A first part is a screw collar 7, or a collar adapter 10 which can be closed and locked around the screw collar 7 to be turned. The collar 7 or the collar adapter 10 has one or more drive engagement elements 11. The second part is a motor housing 20 supporting a motor 19 and a motor drive element 16 such as a spur gear. The motor housing 20 is formed to take its angular support from a falsework post 1 and its vertical support from either the falsework post 1, the screw collar 7 or the collar adapter 10.

Abstract: A power tool includes a motor having an outwardly extending rotor that defines a drive axis, a housing surrounding the motor, and a gearcase that includes a drive train coupled to the rotor and configured to drive a tool output. The gearcase includes a proximal end and an opposite distal end that is exposed to the outside of the tool forward of the housing. The gearcase includes respective locking elements spaced around the periphery of the gearcase proximal end. A motor mount includes spaced apart locking elements that are configured to engage with respective gearcase locking elements. The proximal end portion of the gearcase is adapted to make contact with the motor mount between the locking elements and then rotate such that the gearcase locking elements engage the motor mount locking elements.

Abstract: A tool with a transmission assembly having a reduction gearset and a speed selector. The speed selector has a member, an actuator and a shifter assembly. The member is movable between a first position, in which the member is non-rotatable, and a second position in which the member is coupled to a planet carrier of the reduction gearset for common rotation. The actuator includes a pivoting yoke and a follower that is coupled to the yoke. The follower engages the member so as to be axially movable with the follower. The shifter assembly has a selector switch, a switch fork, and a pair of springs. The selector switch is slidable between a first switch position and a second switch position. The shift fork is slidably coupled to the selector switch and receives the yoke. The springs cooperate to bias the shift fork relative to the selector switch into a neutral position.

Abstract: A hand-held power tool can include a housing, a motor assembly, and a spindle lock assembly. The housing can include a gear case. The motor assembly can be disposed in the housing and be configured to output rotary power to an output spindle. The spindle lock assembly can include an anvil matingly engaged to the output spindle. A ring structure can be rotatably received in the gear case and have a ring body and a reaction tab. A biasing member can be disposed in the gear case and configured to bias the reaction tab in a first predetermined rotational direction.

Abstract: A spindle lock (10) includes a detent arrangement including springs (25) acting on projections (30), each projection engaging one of a pair of recesses (40, 41) to control and buffer the rotation of a spindle (13) and to delay the engagement of locking elements (26a, 26b). A compact, reliable mechanism with a high degree of modularity is achieved by providing the recesses in an inner rotor (31) and the springs and projections in an outer rotor (18) that extends about the inner rotor.

Abstract: A power tool includes a motor having a can and a shaft extending axially from the can, a gear case having an inner surface that defines an opening, a bearing positioned around a portion of the shaft that extends from the can and at least partially within the opening in the gear case, and a motor mount coupled to the motor. The motor mount includes a flange extending away from the motor. The flange of the motor mount and the inner surface of the gear case axially and laterally locate the motor and the gear case on the bearing.

Abstract: A hand-held power tool comprises a motor, an output section which is rotationally driven by the motor, and an output change section which changes the output of the output section in a stepless manner while normally driving the motor. The hand-held power tool is improved so that the output of the output section during working can be smoothly controlled.

Abstract: The invention relates to a gearbox device, in particular, for a hammer drill or chisel, with a torque transmission mechanism, which has a first torque transmitting region for transmission of a torque to a first component and at least one second torque transmitting region for transmitting a torque to a second component. According to the invention, the first torque transmitting region and the second torque transmitting region at least partly have a corresponding partial contour for transmitting the torques.

Abstract: The invention is based on a hand-held power tool, in particular a cordless screwdriver, having a drivable output shaft, a supporting element, and a roller bearing unit that is provided to transmit a supporting force of the output shaft to the supporting element. According to the invention, the output shaft and/or the supporting element constitutes at least one roller element running surface of the roller bearing unit.

Abstract: The present invention relates to a power tool comprises an adjusting mechanism, the adjusting mechanism comprising a station element defining at least a first engaged member, and an adjusting member rotated about a axis and driving the first engaged member to move elastically along the axis, wherein a frequency increase mechanism is disposed between the adjusting member and the station element, the frequency increase mechanism coupled to the first engage member, the frequency of the elastic moving of the first engage member increases when the adjusting member rotates about the axis. Because the adjusting mechanism can increase the sound frequency, so it can make precision and dense sound and remind of the operator when the adjusting member rotated.

Abstract: A control scheme is provided for a power tool having a rotary shaft. The control scheme includes: monitoring rotational motion of the tool generally about a longitudinal axis of the shaft; detecting a condition of the tool based on the rotational motion of the tool; and controlling torque imparted to the shaft upon detecting the tool condition, where the torque is inversely related to an angular displacement of the tool about the longitudinal axis of the shaft.

Abstract: The apparatus, for re-machining safety valves in situ on high pressure/high temperature plant and pipework, comprises a first gearbox and a second gearbox. The first gearbox has a first centre of rotation associated therewith and is configured to receive a driving torque. The second gearbox has a second centre of rotation associated therewith, is coupled to and is configured to be driven by the first gearbox. Coupling means is provided for transferring the drive torque from the first gearbox to the second gearbox. The coupling means is configured to define the location of the second centre of rotation relative to the first centre of rotation. A removable accessory assembly is provided and is coupled to the second gearbox, for carrying out a cutting, grinding or lapping operation to recondition a surface of a safety valve.

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 controller 50 has a single-driving mode/continuous-driving mode changeover switch 233 for performing fastener driving operation in a single driving mode or a continuous driving mode. In a case where the single-driving mode/continuous-driving mode changeover switch 233 instructs a single driving mode, the controller 50 causes a driver blade 3a to perform fastener driving operation when both a trigger switch 5 and a push lever switch 22 are switched, by switching operation, from the one switch status to the other switch status (e.g., the ON status). Consequently, fastener driving operation is made possible regardless of sequence of actuation of the trigger switch 5 and the push lever switch 22.

Abstract: The invention relates to a hand-held power tool for predominantly percussively driven tool attachments, in particular hammer drills and/or a chisel-action hammers. The power tool has a percussion axis and an intermediate shaft that is parallel to the percussion axis and which has a first stroke generating device having a first stroke element for a percussion drive. Additionally, at least one additional second stroke generating device having at least one second stroke element is provided for driving a counter oscillator that is arranged on or about the intermediate shaft and can be driven by the intermediate shaft. A phase displacement that is different from zero and that is unequal to 180° takes place between a movement of the first stroke element and a movement of at least one second stroke element.

Abstract: In view of the above problem, the present invention is to provide an electrical power tool which enables a user to intuitively grasp a rotation direction and a rotation speed of a tip tool. The electrical power tool 1 comprises a chuck 2 provided at a tip of a tool body 3, and rotatable with a tip tool held, and an operation switch 7 having operation protrusions 6 exposed to both side surfaces of a tool body 3 so as to be able to operate, respectively bilaterally symmetrically protruded with a rotation axis of the chuck 2 therebetween, coaxially rotatable with the chuck 2, and urged so as to be self-restored to a neutral position. The chuck 2 is rotated in a direction according to a rotation direction of the switch 7 at a speed according to a rotation angle from the neutral position of the operation switch 7.

Abstract: One aspect according to the present invention includes a cutting unit for a cutting device. The cutting unit has a gear chamber. A partitioning member can partition the gear chamber at a midpoint of a transmission path of rotation of a gear train from an electric motor to a spindle.

Abstract: A machining tool comprises a frame mounting an extendable yoke slidable with respect to the frame in a first direction through one or more mounting pillars. A tool motor is mounted on the yoke. A drive mechanism for the yoke is also mounted in the frame, with a drive motor to drive the yoke drive mechanism. A belt is between pulleys on the drive motor and mechanism to transmit drive between them. A rotatable sleeve is around the tool motor and on which sleeve the belt engages on opposite sides of the tool motor, whereby the tool motor can extend between the drive motor and mechanism, thereby resulting in a compact arrangement of the tool.

Abstract: A hand-held power tool includes a motor-driven percussion mechanism. The percussion mechanism includes a guide tube (21) and 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). The percussion mechanism further includes 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). A connection rod (29) is 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: This invention provides an auto hammer comprising a housing, a head assembly including a striking device and transmission mechanism. The striking device includes a striking rod having a striking end. The transmission mechanism includes an impact wheel. The distance from the end surface of the striking end of the striking rod to the center of the impact wheel between 40 mm and 100 mm. This distance is arranged very small, in favor of the hammer being used in some narrow spaces. The auto hammer according to this invention meets the requirements of being used in narrow spaces by hands, thereby suitable for use in various circumstances.

Abstract: A power tool with a housing, a transmission and a switch mechanism. The switch mechanism has an actuator, a rail, a switch and first and second springs. The actuator is non-rotatably but slidably coupled to the housing for movement along a longitudinal axis of the transmission between a plurality of positions to selectively engage one or more members of the transmission at each of the positions such that the transmission operates in one of a plurality of different overall speed ratios. The rail is fixedly coupled to the actuator and is received through the switch such that the switch is slidably mounted on the rail. The first and second springs are configured to bias the switch relative to the actuator in different directions.

Abstract: A compliant shifting mechanism can change the operation of a power tool between first and second operating conditions. The shifting mechanism can provide two distinct forces on a gear set during movement of the gear set between the two operating conditions. The shifting mechanism can provide a user with a tactile sensation of the completion of the transition between the two operating conditions without the gear set completing the full transition. A shifting mechanism can automatically complete the change between operating conditions, regardless of an alignment between the gear set and another component. The two distinct forces can be a torsional resistance force and a bending resistance force.

Abstract: An electrical device, such as a nailer device, has a motor and a gear housing containing a transmission mechanism. The transmission mechanism is coupled to the motor for driving an impact member. The transmission mechanism includes a shaft having a through-hole wherein a first opening of the through-hole is communicated with the interior of the gear housing and a second opening of the through-hole is communicated with an exterior of the gear housing.