Abstract: A reciprocating saw includes a housing, a motor positioned within the housing and configured to drive a reciprocating saw blade, and a shoe coupled to the housing. The shoe is configured to engage a workpiece. The reciprocating saw also includes a proximity sensor configured to detect the workpiece when engaged with the shoe. The proximity sensor is positioned on a forward end of the housing in a facing relation with the workpiece. In response to the proximity sensor detecting formation of a gap between the shoe and the workpiece, the proximity sensor is operable to deactivate the motor.

Abstract: A reciprocating cutting tool includes a shoe that is less likely to slip off when pulled frontward, for positioning the shoe, beyond a predetermined position such as a maximum pull position. The reciprocating cutting tool includes a motor, a slider being rod-like and including a tip tool holder, a reciprocation converter that converts rotation of the motor to reciprocation in a direction in which the slider extends and transmits the reciprocation to the slider, a shoe slidable in a front-rear direction to come in contact with a workpiece to which the tip tool is applied, a shoe lock unit engageable with the shoe to restrict the shoe from sliding and disengageable from the shoe to allow the shoe to slide, and a pin that interferes with the shoe slid to a predetermined position.

Abstract: A percussive therapy device that includes a housing, an electrical source, a motor positioned in the housing, a switch for activating the motor, a push rod assembly operatively connected to the motor and configured to provide reciprocating motion in response to activation of the motor, and a massage attachment secured to a distal end of the push rod assembly. The reciprocating motion of the push rod assembly has a user-adjustable amplitude.

Abstract: A reciprocating power tool may include a driving system driving a reciprocating mechanism. A selection mechanism provides for selection of a linear mode of operation or at least one orbital mode of operation. Motion of a reciprocating shaft of the reciprocating mechanism may be guided by a guide bracket fixed in the housing and an orbit bushing movably coupled in the housing. The guide bracket may include at least one guide slot having a contoured guide surface that guides the motion of the corresponding end portion of the reciprocating shaft. The contoured guide surface may guide the corresponding end portion of the reciprocating shaft in a corresponding direction relative to the longitudinal centerline of the at least one guide slot during an out stroke and a return stroke of the reciprocating stroke.

Abstract: An accessory for an oscillating power tool includes an attachment portion configured to be coupled to an oscillating power tool and a working portion extending generally along a longitudinal axis. The working portion has a rear end portion coupled to the attachment portion, a front cutting edge opposite the rear end portion, a first side edge extending from the front cutting edge to the rear end portion, and a second side edge opposite the first side edge and extending from the front cutting edge to the rear end portion. The working portion includes an at least partially curved surface that contains the longitudinal axis. At least a portion of the first side edge includes a first side cutting edge portion.

Abstract: A reciprocating tool includes a housing, a first tubular member, a slider, a second tubular member and a lock member. The first tubular member is pivotable around a first axis and has a single first protrusion protruding radially inward. The second tubular member is disposed in the first tubular member, is coupled to a first end portion of the slider to be pivotable around a second axis, and has a single second protrusion protruding radially outward. The second tubular member has a protruding portion configured to allow the lock member to move from a lock position to an unlock position. The single first protrusion is configured to engage with the single second protrusion and cause the second tubular member to pivot when the first tubular member pivots. The single second protrusion is provided on a portion of the second tubular member other than the protruding portion.

Abstract: Exemplary embodiments of massaging devices are disclosed herein. One exemplary embodiment includes a piston having a longitudinal axis, a massaging head connected to the piston, a motor located on a first side of the longitudinal axis and a handle located on a second side of the longitudinal axis. A drive mechanism for moving the piston and massage head is also included.

Abstract: A reciprocating cutting tool reduces deteriorating movement of an operating drum due to entry of chips between the operating drum and a housing. A reciprocating cutting tool includes a motor, a slider being rod-like and extending in a front-rear direction, a reciprocation converter that converts rotation of the motor to reciprocation in the front-rear direction and transmits the reciprocation to the slider, a power transmission housing accommodating the reciprocation converter, a tip tool holder at a front end of the slider to detachably receive a tip tool, and an operating drum operable to attach or detach the tip tool with the tip tool holder through rotation. The operating drum is rotatably held on the power transmission housing with one or more ring members.

Abstract: A reciprocating saw comprises a housing, a blade assembly, a reciprocating rod assembly, a driving assembly and an operation mechanism. The blade assembly extends forward from one side of the housing, and comprises a positioning structure. The reciprocating rod assembly is detachably connected with the blade assembly and comprises a blade fixing structure and an unlocking component matched with the positioning structures. The driving assembly is accommodated in the housing, and drives the reciprocating rod assembly to drive the blade assembly to perform reciprocating motion. The operation mechanism is installed on the housing and moves between a locking position and an unlocking position and comprises an operation button, a drive cam matched with the unlocking components and an elastic reset component for resetting the operation button.

Abstract: A reciprocating tool includes a housing, a support body, a slider, a motor, a driving mechanism, a first biasing member, a manipulation member and a first change mechanism. The housing has a first axis that defines a front-rear direction of the reciprocating tool. The support body is supported within the housing. The slider is supported by the support body to be linearly movable. The driving mechanism is operably coupled to the slider and configured to reciprocally move the slider relative to the support body using power of the motor. The first change mechanism is operably coupled to the manipulation member and configured to selectively enable and disable the first biasing member to bias the slider in response to manipulation of the manipulation member. When biasing of the slider by the first biasing member is enabled by the first change mechanism, the first biasing member biases the slider downward.

Abstract: A surgical tool may move a saw blade in a sagittal plane. The saw blade has a distal blade end with teeth. The surgical tool comprises a handpiece body and a carrier operatively attached to the handpiece body. The carrier is configured for oscillating movement about a pivot axis. A retainer is operatively attached to the carrier for concurrent movement and releasably secures the saw blade in the sagittal plane relative to the handpiece body. An actuator is coupled to the handpiece body to selectively oscillate the carrier relative to the handpiece body such that the retainer and the saw blade pivot back and forth about the pivot axis within the sagittal plane. An ultrasonic transducer is operatively attached to the handpiece body to selectively generate ultrasonic energy to resonate the saw blade such that the teeth at the distal blade end reciprocate proximally and distally within the sagittal plane.

Abstract: A percussive massage device includes a cylinder extending along a longitudinal axis. A motor shaft that rotates about a central axis perpendicular to the longitudinal axis. A crank coupled to the shaft includes a first pivot offset from the central axis. A pinion gear is coupled to the first pivot. The pinion gear rotates within a ring gear. The pinion gear has a second pivot that rotates about the first pivot. A reciprocation linkage is coupled between the second pivot and a piston that moves longitudinally within the cylinder. An applicator head coupled to a second end of the piston has an end exposed outside the cylinder for application to a person receiving treatment. An actuator selectively rotates the ring gear to cause the applicator head to have a first stroke length and at least a second stroke length.

Abstract: A power-driven reciprocating tool may include a transmission mechanism that converts rotational force from a motor to linear force to be output by a reciprocating mechanism coupled thereto, and a counterbalancing mechanism coupled to the transmission mechanism to counter-balance forces generated by the reciprocating mechanism. The transmission mechanism may include a planetary gear assembly including a sun gear in meshed engagement with at least one planet gear. In response to a force converted by and transmitted from the transmission mechanism, the reciprocating mechanism may move in a first linear direction, and the counterbalancing mechanism may move in a second linear direction, opposite the first linear direction. The opposite linear movement of the reciprocating mechanism and the counterbalancing mechanism may counteract forces generated by the reciprocating motion of the reciprocating mechanism, thus reducing vibration output by the tool.

Abstract: A reciprocating saw includes a housing, a motor, and a drive mechanism. The drive mechanism includes a driven gear that is rotated by the motor. The driven gear is vertically-oriented within the housing. The drive mechanism also includes a drive arm coupled to the driven gear to translate rotary motion of the driven gear into reciprocating motion, and an output shaft coupled to the drive arm to reciprocate relative to the housing along a spindle axis through a cutting stroke and a return stroke. The drive mechanism further includes a counterweight coupled to the driven gear for rotation with the driven gear. The counterweight moves toward the spindle axis during a start of the cutting stroke of the output shaft and moves away from the spindle axis during a start of the return stroke of the output shaft.

Abstract: An out-the-front knife comprises a handle having a blade channel, a slider channel, and an opening. A blade in the blade channel is configured to travel along the blade channel. A firing mechanism in the slider channel is configured to extend the blade to an open position and retract the blade to a closed position. The firing mechanism comprises a slider that has a nub that fits into the opening and extends outside the handle. A button has a nub opening that receives the nub and at least one bearing opening. A friction plate is interposed between the button and the handle. At least one bearing is inserted into the at least one bearing opening. The at least one bearing supports the button on the friction plate.

Abstract: An oscillatingly driven machine tool having a housing in which a motor with a motor shaft is received, on which an eccentric element is accommodated, with a spindle head, with a tool spindle that is rotatably mounted about its longitudinal axis in the spindle head, on which a coupling element is non-rotatably received, which cooperates with the eccentric element for generating a movement of the tool spindle which oscillates about its longitudinal axis such that, in addition to the oscillating movement, a differing, superimposed movement is introduced into the coupling element.

Abstract: A blade cartridge for use with a surgical saw includes a bar and a rack. The bar includes a first holding feature for removably holding the bar static to the saw. The rack includes a base moveably disposed in the bar and has cutting teeth defining extending beyond the bar. A drive link extends from the base, providing a second holding feature for releasably engaging a reciprocating drive integral with the saw. One of the base and the bar includes a guide slot. The other of the base and the bar includes a static member extending into the guide slot. The guide slot and the static member allow the rack to reciprocally move from proximal to distal to proximal along a longitudinal axis of the bar. The bar includes two plates and a spacer between the plates. The base is located between the plates.

Abstract: A reciprocating saw includes a housing, a motor positioned within the housing, a drive shaft defining a longitudinal axis, and a spindle positioned substantially within the housing and coupled to a wobble plate. The spindle includes a throughbore formed by a flow welding process, wherein the throughbore extends through the spindle to receive the wobble plate.

Abstract: A massage device that includes a housing, an electrical input, a motor, a switch in electrical communication with the electrical input and the motor and configured to selectively provide power from the electrical input to the motor, an actuated output operatively connected to the motor and configured to reciprocate in response to activation of the motor, and a treatment structure operatively connected to a distal end of the actuated output. The actuated output is configured to reciprocate the treatment structure at a frequency of between about 15 Hz and about 100 Hz, and at an amplitude of between about 0.15 and about 1.0 inches. The combination of amplitude and frequency provides efficient reciprocation of the treatment structure such that the treatment structure provides therapeutically beneficial treatment to a targeted muscle of a user.

Abstract: A power tool includes a housing, a motor, and a drive mechanism. The drive mechanism includes a driven gear that is rotated by the motor. The driven gear is vertically-oriented within the housing and has an upper portion and a lower portion. The drive mechanism also includes a connecting rod coupled to the driven gear to translate rotary motion of the driven gear into reciprocating motion, and an output shaft coupled to the connecting rod to reciprocate relative to the housing through a cutting stroke and a return stroke. The drive mechanism further includes a counterweight coupled to the driven gear for rotation with the driven gear. The counterweight moves through the upper portion of the driven gear during the cutting stroke of the output shaft, and moves through the lower portion of the driven gear during a return stroke of the output shaft.

Abstract: An electric power tool includes a drive device for providing a driving force, a rotation wheel that has a central axis and is driven by the drive device to rotate around the central axis, a spindle that supports a tool holder configured to hold a tool of the electric power tool, a first intermediate member, a second intermediate member, and a counterweight device. The first intermediate member is offset from the central axis of the rotation wheel, and revolves around the central axis when driven by the rotating rotation wheel, while driving the spindle to reciprocate in a first direction. The second intermediate member is driven by the first intermediate member to rotate around the central axis and is disposed to be offset from the central axis of the rotation wheel on the side opposite the first intermediate member. The counterweight device is driven by the second intermediate member.

Abstract: The innovation disclosed and claimed herein, in at least one aspect thereof, comprises continuously charging a cell phone while the user utilizes the cellular phone for ordinary activities (e.g. posting to social media sites, texting, talking, etc.). The signals from routine cellular phone operations will send signals to a photocoupler or other dedicated sensor. The dedicated sensor will output current to drive a magnet mechanism which will in turn drive a fan that generates current to charge to a super/ultra-capacitor.

Abstract: A saw blade includes a blade base with an arcuate cutting edge. The cutting edge is curved to a lesser extent than a circular arc with a radius that corresponds to the distance between the axis of rotation of the saw blade and the cutting edge.

Abstract: The innovation disclosed and claimed herein, in at least one aspect thereof, comprises continuously charging a cell phone while the user utilizes the cellular phone for ordinary activities (e.g. posting to social media sites, texting, talking, etc.). The signals from routine cellular phone operations will send signals to a photocoupler or other dedicated sensor. The dedicated sensor will output current to drive a magnet mechanism which will in turn drive a fan that generates current to charge to a super/ultra-capacitor.

Abstract: An oscillating power tool includes a drive motor producing rotary motion and an actuator for converting the motor rotary motion to an oscillatory side-to-side movement. The power tool includes a tool mount operably driven by the actuator and configured to support the tool so that the working end is substantially collinear and/or coplanar with the axis of the motor drive shaft.

Abstract: An exemplary hand-held, power operated rotary knife dermatome comprises a blade housing assembly and a depth gauge assembly. The blade housing assembly includes an annular blade housing and a blade lock ring for rotatably supporting an annular rotary knife blade. The annular blade housing includes a shield extending radially inwardly from a blade receiving body and including an inner wall defining a tissue directing surface, the tissue directing surface including a first tissue guide surface extending upwardly from a lower end of the shield, the first tissue guide surface extending substantially parallel to the blade housing axially extending center line. The blade receiving body includes an annular blade channel extending axially upwardly from a lower surface of the blade receiving body, a bearing surface axially spaced from a lower surface of the blade receiving body, and a threaded portion formed on the outer surface of the annular blade housing.

Abstract: A reciprocating tool includes a motor, a reciprocating member, and a crank mechanism. The motor is disposed in a housing. The reciprocating member projects from the housing. The crank mechanism converts rotation of a rotation shaft of the motor into reciprocation of the reciprocating member. The crank mechanism rotates around an axis in a lateral direction by rotation transmission from the rotation shaft, and the crank mechanism includes a crank member having an eccentric pin, a connecting rod coupling the eccentric pin to the reciprocating member, and a balancer coupled to the eccentric pin, and the balancer is supported by the eccentric pin alone in the housing.

Abstract: A component placement device is provided. The component placement device includes a machine frame, a subframe supported by the machine frame, and a component pickup unit. The component pickup unit is movable relative to the subframe. The component pickup unit is movable by a first drive at least in a direction of movement. The component placement device includes a movable counter-mass being movable relative to the subframe by a second drive in a direction opposite to the direction of movement of the component pickup unit to at least partially counteract a reactive force exerted on the subframe by the component pickup unit during movement of the component pickup unit in the direction of movement relative to the subframe.

Abstract: Disclosed is a hand-held electric tool, in which a main shaft (1) swings back and forth around an axis (11) to drive accessories (9) of the tool to carry out various types of operations. A swing device is provided with an eccentric element (41) capable of reducing the shock caused to a shell (7) by a connecting rod component (3). Another shell (6) is provided with a valve device (5) used for adjusting the flow of air current in different air ducts. The accessories (9) of the tool can be cooled or cleaned through the air current in one of the air ducts. The main shaft (1) is provided with an elastic support (2) used for balancing the load when an electrical motor (8) is operating. The elastic support (2) can replace a bearing in supporting the main shaft (1) swinging back and forth around the axis (11).

Abstract: To provide an easy-to-use electric chainsaw that uses, in place of a large battery pack with a high voltage rating that would have been used in conventional electric chainsaws, a battery power source composed of a set of small commonly used battery packs of the same rating. An electric chainsaw having a built-in electric motor that is powered by a rechargeable battery, wherein a set of commonly used battery packs of the same rating is used as the rechargeable battery. The set of battery packs is mounted at the back of the main housing so that the center of gravity (G) of the chainsaw is positioned within a range (R) of 1.5 time the width (W) of the grip section of a rear handle between the left and right sides of a center line that is centered in the horizontal direction.

Abstract: A reciprocating tool with a reduced number of parts is provided. A jigsaw reciprocates a saw blade in a direction along an axis with the power of an electric motor. The jigsaw includes a housing accommodating the electric motor, a guide member fixed to the housing and provided along the axis, a connector member sandwiching the guide member and reciprocating when the power of the electric motor is transmitted thereto, and a plunger attached to the connector member and holding the saw blade.

Abstract: In accordance with one embodiment, a reciprocating saw includes a housing, a plunger at least partially positioned within the housing and configured to reciprocate with respect to the housing along a plunger axis, a wobble plate assembly operably connected to the plunger and a motor, a first guide rail supported by the housing and extending longitudinally along the plunger axis, and a spherical component in contact with the first guide rail, the spherical component and the first guide rail configured to inhibit rotation of the wobble plate assembly.

Abstract: In accordance with one embodiment, a reciprocating saw includes a housing, a spindle shaft configured to reciprocate within the housing, the spindle shaft including a plurality of first grooves extending along an axis of the spindle shaft, a locking bushing including an internal bore, the locking bushing supported by the housing such that the plurality of first grooves is at least partially located within the internal bore, the locking bushing including a plurality of axially extending grooves within the internal bore, each of the plurality of axially extending grooves aligned with a respective one of the plurality of first grooves, and a plurality of first ball bearings, each of the plurality of first ball bearings positioned at least partially within a respective one of the plurality of axially extending grooves and the aligned respective one of the plurality of first grooves.

Abstract: A reciprocating tool includes a motor, a reciprocating member, and a crank mechanism. The motor is disposed in a housing. The reciprocating member projects from the housing. The crank mechanism converts rotation of a rotation shaft of the motor into reciprocation of the reciprocating member. The crank mechanism rotates around an axis ma lateral direction by rotation transmission from the rotation, shaft, and the crank, mechanism includes a crank member having an eccentric pin, a connecting rod coupling the eccentric pin to the reciprocating member, and a balancer coupled to the eccentric pin, and the balancer is supported by the eccentric pin alone in the housing.

Abstract: A power tool includes a housing having a front portion and a handle portion. The front portion defines a cavity that encloses a motor and includes a gripping portion surrounding the cavity. An insulating cover is provided on the gripping portion of the housing and includes a gripping surface. A thermoelectric cooling unit is located between the gripping portion of the housing and the insulating cover. The thermoelectric cooling unit has a cold side positioned in thermal contact with an inner surface of the insulating cover and a hot side positioned in contact with an outer surface of the gripping portion of the housing. The thermoelectric cooling unit is configured to absorb thermal energy from the insulating cover via the cold side of the thermoelectric cooling unit and to release the absorbed heat via the hot side of the thermoelectric cooling unit.

Abstract: An accessory configured for use with a reciprocating saw having a spindle. The accessory is configured to reciprocate with the spindle. The accessory includes an attachment portion having a tang including a first tang member and a second tang member and an aperture that extends through the attachment portion from a first broad side to a second broad side. The attachment portion also includes a first radius, which terminates to define a projection, located on a first narrow side. The attachment portion also includes a second radius, which terminates to define a projection, located on a second narrow side. The first radius and the second radius are configured to contact an exterior of the spindle.

Abstract: A hand-held power tool drive device includes at least one wobble drive unit that has at least one rotatably mounted drive element, with at least one wobble unit positioned on the at least one drive element. The drive device also includes at least one counterweight unit that has at least one movably mounted compensating element configured to be driven by the at least one wobble unit. The at least one wobble unit includes at least one force application point that is configured to drive the at least one compensating element. An axis extending through a rotational axis of the at least one drive element and the at least one force application point encloses an angle of between 0° and 135° with a wobble element longitudinal axis of a wobble element of the at least one wobble unit.

Abstract: A surgical instrument arrangement has a modular motor drive unit which has a drive arrangement having at least one output element, an instrument shaft that can be detachably connected to the drive unit, and a drive arrangement having at least one input drive element. The output drive arrangement and the input drive arrangement can be coupled to each other by a mechanical interface that has at least one single-sided linkage, a pin, and a cut-out, wherein the pin can be radially expanded in the cut-out. Alternatively, a gap may be formed between the pin and the cut-out, which gap is wavy in the radial direction, and in which a radially displaceable, axially fixed intermediate element arrangement is arranged. The surgical instrument arrangement may also include a sterile barrier, which is provided to envelop the drive unit and to be arranged between the drive unit and the instrument shaft.

Abstract: A power tool includes a housing, a blade assembly, a drive assembly within the housing for driving the blade assembly, and a cover that is coupled to the power tool and is movable between at least two positions. The blade assembly is fixedly retained by the power tool when the cover is in a first position and is detachable from the power tool when the cover is in a second position. The cover has tool-less means for coupling the blade assembly to the cover when the cover is in a second position.

Abstract: A reciprocating power tool has a shoe that can be adjusted while the reciprocating power tool is in use. The reciprocating power tool has a main body, a first grip, a second grip moveable with respect to the main body, and a shoe for engaging a workpiece. The shoe is coupled to the second grip such that the shoe moves with the second grip for adjustment of a position of the shoe when the second grip is moved with respect to the main body.

Abstract: A saber saw including: a motor; a housing accommodating the motor; a plunger held to be reciprocatable in the housing and to which a blade is mounted at a leading end thereof, and a movement converting part provided between the motor and the plunger and is configured to convert rotation movement of the motor into reciprocating movement of the plunger, wherein a bearing metal is fixed to an outer peripheral surface of the plunger.

Abstract: A dust shroud for reciprocating saws has a shroud body with bristles, a vacuum port and an attachment collar attached to the shroud body. The shroud has a slot formed through the collar and shroud body and is expandable and collapsible to fit different sizes of reciprocating saws.

Abstract: A pneumatic valve assembly with a trigger for switching the pneumatic valve assembly between two or more valve operation modes is disclosed herein. The valve operational modes are determined by selection of fluid conduits by a trigger valve assembly of the pneumatic valve assembly which interconnects fluid conduits to a main valve, pilot valves and a pneumatic cylinder of a fluid powered pole saw and wherein a piston located in the pneumatic cylinder is mechanically coupled to a cutting blade of the pole saw and the trigger is operatively coupled to the trigger valve assembly.

Abstract: A power tool can have a compact power tool handle. A compact power tool handle can be used in a jigsaw, or any other power tool with a handle. Optionally, the power tool can have a compact power tool handle which has an AC compact variable switch which can control the speed of a motor of the power tool.

Abstract: A hand-guided jig saw includes a tool housing that houses a drive motor. The drive motor is configured to drive a reciprocating transmission that drives a reciprocating unit connected to a tool receptacle. A vertical axis of the tool receptacle saw is configured to receive a saw blade. In order to enable at least partial free cutting of the saw blade for forming a sawing passage in a workpiece, the tool receptacle, via an electromechanical actuating system, is pivotable by a pre-defined angle about a vertical axis. A pivoting movement of the saw blade is superimposed by at least a reciprocating movement of the tool receptacle.

Abstract: A power tool clamping device comprises at least one clamping unit having at least one movably mounted force-fit clamping plane element and at least one actuating element configured to move the at least one force-fit clamping plane element to clamp a working tool at least in a clamping position. The at least one actuating element is mounted movably relative to the at least one force-fit clamping plane element along at least two at least substantially mutually transverse movement directions of the at least one actuating element.

Abstract: A power tool includes a tool operable to work on a workpiece, a drive mechanism coupled to the tool and operable to move the tool, and a housing defining an interior. The drive mechanism is disposed within the interior. A handle has a first end and a second end. The first end is fixed to the housing and the second end is spaced apart from the housing to define a gap therebetween. An insert is fixedly attached to the housing and the second end to fill the gap. The insert is more flexible then the handle and the housing.

Abstract: An improved vibration dampening system has been developed for handheld electrical power tools. The vibration dampening system includes a material that a controller selectively activates with an electrical current to increase the rigidity of the material and dampen random vibrations detected by the controller. The material is positioned between a foot member that helps support the tool against a work piece and both hand grips for the tool. Thus, the vibration dampening system reduces the impact of random vibrations on both hands of an operator.

Abstract: A pneumatically powered pole saw is provided, the pole saw having gas actuated main valves configured for movement between first positions and second positions wherein the gas actuated main valves are located in a main valves assembly fluidly coupled to the piston chamber; and a first pilot valve is configured to send actuating gas through a conduit to the main valves assembly and a second pilot valve is configured to send actuating gas through a conduit to the main valves assembly wherein the cutting blade moves in opposite directions in response to the actuating gas of the first and second pilot valves.

Abstract: A reciprocating drive mechanism for a power tool includes a rotatably mounted transmission shaft that has a first central axis, a spindle with a spindle body, and a counterweight for linearly reciprocating motion under the guide of at least one guiding rod. A wobble plate is mounted on the transmission shaft and includes a first arm and second arms extending in opposite directions. The first arm and second arms are configured to cooperate with the spindle and the counterweight respectively so that, upon rotation of the transmission shaft, the first and second arms of the wobble plate drive the spindle and the counterweight to reciprocate in opposite directions parallel to the second central axis. An angle is formed between the extending direction of the first arm and the second arm and a plane defined by the first central axis and the second central axis.