Abstract: A hand-held tool, in which multiple fasteners are successively fed, is provided with: an ejection detecting portion for detecting an ejection of the fasteners; and a control portion for switching from a power saving wait mode of small power consumption to an active mode capable of executing normal processing when the ejection detecting portion detects the ejection of the fasteners, and for switching from the active mode to the wait mode when the normal processing is ended.

Abstract: A stitching head is provided having a cam connected to the bender rail rail, the cam operates to redirect the staple driving force being applied by the driver rail to the driver and upon the staple during the staple driving step of stitching head operation; the force-redirecting position of the cam is automatically adjusted in response to the thickness of each workpiece as the cam is connected to the bender rail rail and the contacting of the workpiece by the bender rail repositions the cam at the desired distance above the workpiece to reestablish the set-point for the redirection of the staple driving force being applied to the driver rail upon as staple head contacts each variable thickness workpiece.

Abstract: A power tool including an activation arm assembly having an actuator coupled to the activation arm assembly, the activation arm assembly being coupled to the structure and including a roller assembly having a roller, wherein actuation of the actuator causes the roller assembly to translate toward and engage the driver to initiate driving engagement between the driver and the flywheel; The activation arm assembly further includes a follower arm that engages the roller, the follower arm including a first mounting portion and a second mounting portion, the second mounting portion being pivotally coupled to the actuator and slidingly engaged with the carriage, the first mounting portion being biased in a direction toward the driver. The follower arm has a non-linear profile.

Abstract: A full-thickness resection system is disclosed. In an embodiment for the resection system, the system may include a flexible shaft, a flexible guide member disposed within the flexible shaft, a stapling mechanism disposed around the flexible guide member, and a grasper. The stapling mechanism has an elongated portion that is at least partially disposed within the flexible shaft. The stapling mechanism includes a stapling arm and an anvil arm. The stapling arm has a longitudinal axis and includes a stapling head having a longitudinal axis. The anvil includes an anvil head. The stapling arm and anvil arm extend from the elongated portion of the stapling mechanism and are moveable with respect to each other between a tissue receiving position and a stapling position. The grasper extends through the flexible shaft and is adapted to grasp a portion of a tissue that is to be excised from an organ in the patient's body.

Abstract: The invention is a dual head mechanical nailer and method capable of driving a pair of nails, screws, staples, or other forms of attachments into a drywall corner bead at an offset orientation and at an angle where each of the attachment means is ninety degrees from the other. The nailer can be powered by combustible fuel, by pneumatic power, by electric power supplied by a battery, or by electric power supplied by an electrical service connection. A magazine of nails, screws, staples, or other forms of attachments may be attached to each head of the mechanical nailer for supplying the respective head with the respective attachment.

Abstract: When a work stops without driving after a voltage across a capacitor circuit reaches a target boost voltage, a micro-computer switches an FET through a driver circuit. As a result, the voltage charged in the capacitor circuit is charged in a secondary battery through the FET, an inductance, and a parasitic diode of an FET.

Abstract: A pneumatic fastening tool may include a tool housing including a dispensing portion for dispensing a fastener, a handle portion and an inlet configured to receive input of compressed air. A cap assembly may include a cap housing having an opening and mounted to the tool housing. A deflector may be configured to direct exhausted air through an outlet in a first direction. The deflector may have a stem received in the opening. The stem may define a bore extending in a second direction that is distinct from the first direction. A locking member may extend at least partially in the bore and be configured to rotatably capture the deflector relative to the cap housing.

Abstract: A hand-held drive-in tool for driving in fastening elements includes a drive-in ram (13), a drive (30) for driving the drive-in ram (13) and having a driving spring member (31) for displacing the drive-in ram (13), a device (70) for preloading the driving spring member (31), a locking device (50) having a locking position (54) in which the locking device (50) retains the driving spring member (31) in its preloaded position and a release position (55) into which the locking device (50) is displaced upon actuation of an actuation switch (19) of the drive-in tool (10), and a mechanical blocking device (60) operating independently of the actuation switch (19) and having an active position (68) in which the blocking device (60) retains the locking device (50) in its locking position (54), and a passive position (69) in which the locking device (50) can be displaced in its release position (55).

Abstract: In a gas combustion type driving tool, a measuring chamber 22 is provided in an intermediate part of a gas pipeline 11 between a gas canister 7 and a combustion chamber 2. A solenoid valve 23 is provided in the measuring chamber 22. When fuel gas is supplied to the combustion chamber, an upstream side gas pipeline 11a and a downstream side gas pipeline 11b of the measuring chamber 22 are opened for a predetermined opening time by the solenoid valve 23 to supply the fuel gas within the measuring chamber 22 to the gas pipeline 11b by an injection pressure of the fuel gas in the gas canister 7.

Abstract: A fastener driving tool includes a flywheel rotated by a drive unit and having a wheel rim formed with teeth, an impact member having a mating toothed unit movable with a carrier frame to engage the teeth so as to be swept thereby to an end-stroke position to enable a striking rod to drive a fastener into a targeted workpiece, and an actuating unit configured to actuate the carrier frame to move from an upper position to a lower position in response to a triggering action of a trigger so as to move the mating toothed unit from an disengaging position to an engaging position.

Abstract: According to one aspect of the application, a device for driving a fastening element into a substrate has an energy-transfer element for transferring energy to the fastening element. The energy-transfer element can move preferably between a starting position and a setting position, wherein the energy-transfer element is located, before a driving-in procedure, in the starting position and, after the driving-in procedure, in the setting position. According to another aspect of the application, the device comprises a mechanical-energy storage device for storing mechanical energy. The energy-transfer element is then suitable preferably for transferring energy from the mechanical-energy storage device to the fastening element.

Abstract: A floating impact apparatus for an electrical nail gun includes a carrier, an impact unit, and a floating unit. The impact unit includes an impact member, and at least one sliding, wheel disposed pivotally on the impact member. The floating unit includes a guiding rod together with the impact member being connected movably to the carrier, two floating members extending through the carrier to connect with the guiding rod at positions proximate to a first side of the carrier, and at least two resilient members disposed between a second side of the carrier and the floating members for biasing the guiding rod and the impact member to move relative to the carrier to thereby maintain contact between the sliding wheel and the first side of the carrier, so as to promote smooth movement and nail-striking force of the impact member.

Abstract: A staple refill including a refill body accommodating sheet-type connected staples. The refill body includes a bottom wall, a right wall provided on a right side of the bottom wall and formed with a vertically extending right guide slot, and a left wall provided on a left side of the bottom wall and formed with a vertically extending left guide slot. A pressing member is provided in the refill body in a movable manner to press the sheet-type connected staples. The pressing member includes a guide shaft guided along the right and left guide slots. The guide shaft includes a right end portion protruding outside the right wall through the right guide slot, and a left end portion protruding outside the left wall through the left guide slot.

Abstract: A controller controls a first FET to go on and off based on an input signal of a trigger switch and a push switch and controls a second FET to go on and off based on an input signal of a trigger switch, a push switch, and a operation detection switch. The controller then controls the time that the first FET is on for to be longer than the time the second FET is on for.

Abstract: An electromagnetic nail gun with a lever, comprising a handle for holding the nail gun and triggering the operation of the nail gun, an electromagnetic lever driving device for driving nails with variable speeds through the movement of the lever, wherein electromagnetism is used as driving force, a firing pin slideway for allowing the lever to move therein, and a muzzle magazine assembly for loading nails inside. The present invention uses the magnetism as driving force directly and then applies the lever and variable speed drive to launch nails. Therefore, the structure of the present invention is very simple, light, the manufacture cost is decreased drastically, vibration and noise when used are quite little, very convenient to operate, dispense with the air compressor, easy to carry around.

Abstract: A nailer device includes a housing having a nozzle portion formed in an upper end thereof. A motor and a rotary-linear motion transmission mechanism are arranged in the housing and the rotary-linear transmission mechanism functions to couple an output shaft of the motor to a striking rod disposed in the nozzle portion to thereby move the striking rod in a reciprocating manner. A bias device exerts a force on the striking rod towards the outside of the housing along a longitudinal direction of the striking rod.

Abstract: A refill for staples, which can not be removed from a cartridge unless all sheet-type connected staples in a stapler body are delivered. A refill for staples is installed in a detachable manner in a stapler body, and includes a refill body which holds the sheet-type connected staples, and a pressing member which presses the sheet-type connected staples. A delivery port delivering the sheet-type connected staples and a locking plate provided with a locking section which locks a locked section in the stapler body are formed in the refill body. When the sheet-type connected staples are pressed, the pressing member is engaged with the locking plate not to allow rotation of the locking plate, and, when the sheet-type connected staples are not pressed, the pressing member is disengaged from the locking plate to allow rotation of the locking plate. Thereby, the locking section of the locking plate can be removed from the locked section in the stapler body.

Abstract: A portable linear fastener driving tool is provided that drive staples, nails, or other linearly driven fasteners. The tool uses a gas spring principle, in which a cylinder filled with compressed gas is used to quickly force a piston through a driving stroke movement, while a driver also drives a fastener into a workpiece. The piston/driver is then moved back to its starting position by use of a rotary-to-linear lifter, and the piston again compresses the gas above the piston, thereby preparing the tool for another driving stroke. The driver has protrusions along its edges that contact the lifter, which lifts the driver during a return stroke. A pivotable latch is controlled to move into either an interfering position or a non-interfering position with respect to the driver protrusions, and acts as a safety device, by preventing the driver from making a full driving stroke at an improper time.

Abstract: A hand-held drive-in tool (10) for fastening elements (60) includes a driving unit (30) for a drive-in ram (13) which is displaceably mounted in a guide (12), and has at least one driving element for the drive-in ram (13) formed by an elastomeric band (31) and tensioned by a tensioning device (70).

Abstract: A pneumatic fastening tool may include a tool housing including a dispensing portion for dispensing a fastener, a handle portion and an inlet configured to receive input of compressed air. A cap assembly may include a cap housing having an opening and mounted to the tool housing. A deflector may be configured to direct exhausted air through an outlet in a first direction. The deflector may have a stem received in the opening. The stem may define a bore extending in a second direction that is distinct from the first direction. A locking member may extend at least partially in the bore and be configured to rotatably capture the deflector relative to the cap housing.

Abstract: A staple refill includes a refill body accommodating sheet-type connected staples. The refill body includes a bottom wall, a right wall provided on a right side of the bottom wall and formed with a vertically extending right guide slot, and a left wall provided on a left side of the bottom wall and formed with a vertically extending left guide slot. A pressing member is provided in the refill body in a movable manner to press the sheet-type connected staples, the pressing member including a guide shaft guided along the right and left guide slots. The guide shaft includes a right end portion protruding outside the right wall through the right guide slot, and left end portion protruding outside the left wall through the left guide slot.

Abstract: A staple cartridge is provided with: a refill which houses in a wound manner a staple sheet formed by coupling a plurality of straight staples and includes a guide passage for carrying out the staple sheet; and a cartridge body which includes a feeding passage for guiding the staple sheet carried out from the refill via the guide passage to a position of driving out by the driver. The guide passage is communicated with the feeding passage when the refill is attached to the cartridge body, and the refill is attached to and detached from the cartridge body from a direction different from a direction along which the guide passage and the feeding passage are communicated.

Abstract: A fastening device that drives one or more fasteners into a workpiece generally includes a tool housing and a multistage solenoid contained in the tool housing. The multistage solenoid includes an armature member that travels through at least a first stage, a second stage, and a sense coil disposed therebetween. A driver blade assembly includes a blade member connected to the armature member. The driver blade assembly is operable between an extended condition and a retracted condition. A control module determines a position of the armature member relative to at least one of the first stage and the second stage based on a signal from the sense coil. The control module adjusts a force imparted on the armature by at least one of the first stage, the second stage, and a combination thereof based on the signal from the sense coil.

Abstract: A nailer device has a housing containing a motor, a gear box, a transmission mechanism, and a striking rod. The motor, the gear box, and the transmission mechanism cooperate to cause the striking rod to be moved back and forth. The striking rod has a peripheral outer surface and a longitudinal axis and the striking rod and the gear box are connected through a sliding connection structure which allows the striking rod to be moved along its longitudinal axis and which prevents the striking rod from rotating around its longitudinal axis.

Abstract: An auto hammer having a housing having a grip portion defining a central axis and a head assembly including a striking device which has a striking rod defining a central axis. The striking device is pivotable relative to the grip portion and the angle between the central axis of the grip and the central axis of the striking rod can range between 60° and 180°. The auto hammer thus provides a pivotable striking device and is thereby suitable for different working circumstances.

Abstract: A staple leg cutting mechanism includes a fixed cutter interposed between staple legs penetrated through binding sheets and a pair of movable cutters disposed movable from the outside of the staple legs to the inside thereof, and a clincher mechanism that includes a pair of movable clinchers, respectively disposed on the lower surface side of their associated movable cutters. The staple legs penetrated through the binding sheets are formed in an inwardly curved manner by the movable clinchers and are then guided into and between the movable cutters and fixed cutter. The movable cutters are moved from the outside of the staple legs to the inside thereof to cut the leading end portions of the staple legs, and the staple legs are bent along the binding sheets by the movable clinchers.

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: A device for driving a plurality of fasteners includes a driver assembly having a drive block, a flywheel and a driver mount. The driver mount is configured to move between a first position where the flywheel is removed from the drive block and a second position where the flywheel engages the drive block. The device also includes a work contact element configured to move between an extended position and a depressed position. A blocking arm is connected to the work contact element and configured to move with the work contact element. The blocking arm is positioned in a path of movement of the driver mount when the work contact element is in the extended position. The blocking arm is removed from the path of movement of the driver mount when the work contact element is in the depressed position.

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: A fastening device that drives one or more fasteners into a workpiece generally includes a tool housing and a multistage solenoid contained in the tool housing. The multistage solenoid includes an armature member that travels through at least a first stage, a second stage, and a sense coil disposed therebetween. A driver blade assembly includes a blade member connected to the armature member. The driver blade assembly is operable between an extended condition and a retracted condition. A control module determines a position of the armature member relative to at least one of the first stage and the second stage based on a signal from the sense coil. The control module adjusts a force imparted on the armature by at least one of the first stage, the second stage, and a combination thereof based on the signal from the sense coil.

Abstract: A portable linear fastener driving tool is provided that drive staples, nails, or other linearly driven fasteners. The tool uses a gas spring principle, in which a cylinder filled with compressed gas is used to quickly force a piston through a driving stroke movement, while a driver also drives a fastener into a workpiece. The piston/driver is then moved back to its starting position by use of a rotary-to-linear lifter, and the piston again compresses the gas above the piston, thereby preparing the tool for another driving stroke. The driver has protrusions along its edges that contact the lifter, which lifts the driver during a return stroke. A pivotable latch is controlled to move into either an interfering position or a non-interfering position with respect to the driver protrusions, and acts as a safety device, by preventing the driver from making a full driving stroke at an improper time.

Abstract: A hand-operated drive-in power tool for fastening elements is disclosed. The tool has a drive arrangement for a drive-in ram displaceably arranged in a guide, which has at least one drive element for the drive-in ram made at least partially of an elastomer that is tensible via a tensioning device. To improve the drive-in power tool, a heating device for the at least one elastomer drive element is provided.

Abstract: An object of the application is to improve power transmission to a movable element in a driving tool. The driving tool for driving a material to be driven into a workpiece includes rotationally driven first and second rotating elements, the movable element that can move in a direction that strikes the material to be driven, V-shaped first and second contact surfaces formed on the movable element, and a pressing member that applies a force to the movable element such that the first and second contact surfaces are pressed against the first and second rotating elements. The driving tool further includes a first motor for driving the first rotating element and a second motor for driving the second rotating element.

Abstract: A hand-held tool with a backbone, a motor assembly that is mounted to the backbone, and a plastic housing. The motor assembly can include a driver and can be selectively actuatable to translate the driver along an axis. The plastic housing can be coupled to the backbone and can shroud at least a portion of the backbone.

Abstract: A portable linear fastener driving tool is provided that drive staples, nails, or other linearly driven fasteners. The tool uses a gas spring principle, in which a cylinder filled with compressed gas is used to quickly force a piston through a driving stroke movement, while a driver also drives a fastener into a workpiece. The piston/driver is then moved back to its starting position by use of a rotary-to-linear lifter, and the piston again compresses the gas above the piston, thereby preparing the tool for another driving stroke. The driver has protrusions along its edges that contact the lifter, which lifts the driver during a return stroke. A pivotable latch is controlled to move into either an interfering position or a non-interfering position with respect to the driver protrusions, and acts as a safety device, by preventing the driver from making a full driving stroke at an improper time.

Abstract: A fastening device that drives one or more fasteners into a workpiece generally includes a tool housing and a multistage solenoid contained in the tool housing. The multistage solenoid includes an armature member that travels through at least a first stage, a second stage, and a sense coil disposed therebetween. A driver blade assembly includes a blade member connected to the armature member. The driver blade assembly is operable between an extended condition and a retracted condition. A control module determines a position of the armature member relative to at least one of the first stage and the second stage based on a signal from the sense coil. The trigger assembly is connected to the control module and partially contained within the housing. The trigger assembly is operable to activate a driver sequence that moves the driver blade between the retracted condition and the extended condition.

Abstract: A driving tool of the invention includes a motor, a flywheel that is rotationally driven by the motor, an operating member that drives a material to be driven, an operating member actuation mechanism that selectively transmits a rotating force of the flywheel to the operating member and drives the operating member. The flywheel includes a driving-side member that is rotationally driven by the motor, a driven-side member that transmits a rotating force to the operating member, and a clutch member that connects the driving-side member and the driven-side member when the rotation speed of the motor is a predetermined speed or higher, while releasing the connection between the driving-side member and the driven-side member when the rotation speed of the motor is lower than the predetermined speed.

Abstract: A nose piece for inserting fixing elements into predefined seats in a work piece includes a drive channel for receiving a lower end of a drive rod. The drive rod is movable from an initial upper position, through a first intermediate position, to a lower position when acted on from above on by a drive force. A lower face of the nose piece is adapted to receive a first fixing element. At least one finger is biased toward a side wall of the nose piece. When the drive rod exerts a force on an actuator, the actuator moves the finger from a closed position, in which a lower portion of the finger is disposed under an outer portion of the flange of the first fixing element, to an open position, in which the lower portion of the finger is disposed away from under the outer portion of the flange of the first fixing element.

Abstract: A fastening device that drives one or more fasteners into a workpiece generally includes a tool housing and a multistage solenoid contained in the tool housing. The multistage solenoid includes an armature member that travels through at least a first stage, a second stage, and a sense coil disposed therebetween. A driver blade assembly includes a blade member connected to the armature member. The driver blade assembly is operable between an extended condition and a retracted condition. A control module determines a position of the armature member relative to at least one of the first stage and the second stage based on a signal from the sense coil. The trigger assembly is connected to the control module and partially contained within the housing. The trigger assembly is operable to activate a driver sequence that moves the driver blade between the retracted condition and the extended condition.

Abstract: An electric driving machine includes a remaining fastener sensor 257 which detects the amount of fasteners (e.g., nails) remaining, in an aligned and held manner, in a magazine 2 and which generates a residual-quantity signal (a signal showing depletion of fasteners) when the amount of remaining fasteners has decreased to a predetermined level or less; a remaining fastener detection circuit 406 which outputs a control signal (a signal of level 0) for controlling control means (299, 283, and other means) in accordance with an input of the residual-quantity signal (a switch-on signal) generated by the remaining fastener sensor 257; and a delay circuit 401 for delaying the remaining signal (the ON signal) generated by the remaining fastener sensor 257 by a predetermined period of time (e.g., 20 milliseconds) and inputs the thus-delayed remaining signal to the remaining fastener detection circuit 256 (406).

Abstract: A device for impacting a fastener in one embodiment includes a drive mechanism configured to impact a fastener, a lever arm pivotable between a first position and a second position, and a motor including a plurality of permanent magnets mounted on a rotatable housing, the motor mounted on the lever arm such that when the lever arm is in the first position, the rotatable motor housing is isolated from the drive mechanism and when the lever arm is in the second position, the rotatable motor housing is positioned to transfer rotational energy to the drive mechanism.

Abstract: A stapler has a drive train that drives a stapling head toward a base part in a driving stroke and away from the base part in a return stroke. To accommodate thick workpieces to be stapled, without jamming, the drive train includes a coupling constructed so that its effective connection between coupled parts is releasable and so that it loses its effective connection during the driving stroke to prevent jamming.

Abstract: A device for impacting a fastener in one embodiment includes a frame, a motor mounted to the frame and including a drive shaft defining a drive shaft axis, a lever arm including a pivot axis parallel with the drive shaft axis, a flywheel rotatably mounted on the lever arm and operably connected to the motor for storing energy received from the motor, a drive mechanism for impacting a fastener, and a solenoid configured to pivot the lever arm between a first position wherein the flywheel is spaced apart from the drive mechanism and a second position wherein the flywheel can contact the drive mechanism.

Abstract: A fastener driving tool arranged to drive fasteners into a workpiece includes at least one electric motor having a central stator and an external rotor arranged to rotate around the stator. The rotor may be in the form of a flywheel. The tool includes an energy transfer member such as a driver arranged to transfer kinetic energy from the rotor to a fastener held in the tool, thereby to drive the fastener from the tool into a workpiece. The electric motor may be a brushless motor. The tool may include two such motors, arranged such that both of their rotors propel the driver simultaneously.

Abstract: The new invention is a portable tool, specifically directed electric motor driven nail gun. It has a nail push system, also a motor. The motor uses a flywheel as a speed reduction mechanism, the main characteristic is that the drive unit of the driving mechanism is connected to a pitman by a pin axis on one end, and the other end is connected to the pin axis which does the arc movement. The end of the drive unit props up the long slot by a spring and enclosed by the long slot in a sliding movement. The rectilinear reciprocating drive unit is governed by a clutching mechanism mounted on the speed reduction mechanism. The new invention can provide a powerful impacting force. The clutch bar of the driving mechanism has an outer bulge and inner bulge, it controls the tension spring which makes the drive unit impact nails and recover after impacting nails, without any memory of the rotating state.

Abstract: A fastener driving apparatus includes a power source, a control circuit, a motor, a first cylinder, a first piston, a linear motion converter, a second cylinder, a second piston, an anvil, a valve arrangement and at least one sensor. During a compression stroke, the first piston is configured to compress gas in a first cylinder to a predetermined pressure. At the predetermined pressure, the valve arrangement assumes an open position for communicating the compressed gas to the second cylinder, thereby causing the second piston to move linearly and enabling the anvil to drive the fastener into the workpiece. During a return stroke, at a predetermined position of the first piston in the first cylinder, the valve arrangement assumes the open position for communicating a vacuum created in the first cylinder to the second cylinder and thereby causing the second piston and the anvil to retract to their initial positions.

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 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.

Abstract: A nailer device is carried within a housing having a nozzle portion wherein the nozzle portion is connected with the housing via a head portion of the housing. The nozzle portion includes a sleeve, a fixing member, and a magnetic member located between the sleeve and the fixing member. The fixing member is mounted on the sleeve and the fixing member has a groove in which the magnetic member is arranged.

Abstract: A nailer device has a housing containing a motor and a transmission mechanism. The housing has a nozzle portion with a striking rod for striking a nail arranged therein, the striking rod being moved in a reciprocating manner. A rotating shall is mounted in the housing and the rotating shaft is coupled to the output shaft of the motor through the transmission mechanism. An impact member surrounds the rotating shaft and is moved with the rotating shaft. Corresponding slots are formed on the rotating shaft and the impact member respectively and mate with each other with engagement members being contained in the corresponding slots.