Abstract: It is an object of the invention to provide a rational forced vibration of a dynamic vibration reducer in an impact tool that linearly drives a tool bit in an axial direction of the tool bit via a swinging member. An impact tool includes a motor 111, a swinging member 129 that swings in the axial direction of a tool bit 119 by rotation of the motor 111, a driving element 141 that is caused to reciprocate by swinging movement of the swinging member 129 and a first air chamber 143a in which pressure is fluctuated by reciprocating movement of the driving element 141, and the tool bit 119 is driven by pressure fluctuations of the first air chamber 143a. The impact tool further includes a second air chamber 163 in which pressure is fluctuated by swinging movement of the swinging member 129, and a dynamic vibration reducer 151 having a weight 155 and an elastic element 157 which exerts a biasing force on the weight 155.

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.

Abstract: The invention relates to a multi-gear transmission device, particularly a two-gear transmission device, for transferring a drive torque from an input side to an output side, which transmission device has at least two selectable gear ratios. The multi-gear transmission device further has a multi-stage clutch device, particularly a two-stage clutch device, with at least two different, selectable limit torques. According to the invention, the multi-stage transmission device has at least two preferably switchable translating gear pairs, and the multi-stage clutch device is included in the translating gear pairs.

Abstract: A hand-held power tool includes a pneumatic percussion mechanism having a percussion piston reciprocating along a percussion axis and having a bore extending at an angle to the percussion axis, and an air spring for displacing the percussion piston.

Abstract: In an impact tool including a spindle, an anvil, and an impact mechanism having a hammer and a coil spring, a restricting portion is provided at a front surface of a large-diameter portion of the spindle so as to receive a rear end of the coil spring and to restrict an inner diameter of the rear end of the coil spring. A ring-shaped groove is formed at a rear surface of the hammer to receive a front end of the coil spring, in a manner which provides an inner cylindrical portion at a rear side of the hammer. A run-off portion is formed in the restricting portion so as to allow the inner cylindrical portion of the hammer to move thereinto, so that the hammer can move backward for a distance corresponding to a depth of the run-off portion.

Abstract: A torque overload clutch for an electrical power tool, such as a percussion hammer drill, is provided. The clutch is accommodated in a cavity in a gear cog. Spring washers are used to urge ball bearings into indentations formed in the base of the cavity. The ball bearings are accommodated in cavities formed in a drive plate which engages with the spindle drive of the power tool. The spring washers are held in position by a circlip or a threaded plate. The threaded plate arrangement provides means for compressing the spring washers with a consistent force across a manufactured batch. A method of manufacturing the clutch is also disclosed.

Abstract: It is an object of the invention to provide a technique for a reduction of an impact force cased by rebound of a tool bit after its striking movement in an impact power tool. The representative impact power tool includes a tool body, a hammer actuating member, a striker, a weight and an elastic element. A reaction force is transmitted from the hammer actuating member to the weight and the elastic element is elastically deformed when the weight moves ward by the reaction to absorb the reaction force. The invention is characterized in that the mass of the weight is set to about 40% or more of the mass of the striker.

Abstract: It is an object of the invention to provide a technique which is effective in improving the durability of an angular positioning device of a tool bit and in reducing weight of a tool body in an impact tool. A representative impact tool includes a tool body, a lubricant sealed in the housing space, a driving mechanism, a tool holder, an angular positioning device disposed on a tip end side of the tool body and serves to fix a position of the tool bit around the axis with respect to the tool body. The angular positioning device includes first and second locking members. The first locking member is disposed between the tool body and the tool holder. The second locking member is disposed opposite to the first locking member. One end of the first locking member in the axial direction of the tool bit extends into the housing space of the tool body and is connected to the tool body within the housing space.

Abstract: The invention relates to a wobble drive of a hand-held machine tool, particularly a drilling or chipping hammer, having a drive shaft, a wobble bearing disposed on the drive shaft, and a wobble plate supported on the wobble bearing. At least two wobble fingers having wobble finger axes being provided on the wobble plate. The invention provides that the axes of the wobble fingers form an angle different from 180°.

Abstract: A powered hammer includes a housing, a tool holder coupled to the housing and configured to hold a tool, a motor within the housing, a cylinder disposed within the housing, and a piston slideably mounted within the cylinder. A drive mechanism converts rotary output of the motor into a reciprocating motion of the piston. The drive mechanism includes a crank shaft rotationally driven by the motor, a drive pin eccentrically mounted on the crank shaft, and a con rod with a first end connected to the drive pin and a second end connected to the piston. A ram is slideably mounted forward of the piston that is reciprocatingly driven by the piston. A beat piece is slideably mounted forward of the ram. The beat piece is repetitively struck by the reciprocating ram, which in turn repetitively strikes an end of the tool when held in the tool holder to transfer the momentum of the ram to the tool. Lubrication fluid covers at least part of the drive mechanism.

Abstract: A power tool includes an output member (8) projecting from the tool housing (4), a drive (6) located in the housing for rotating the output member (8), and a slip clutch (22) for transmitting torque from the drive (6) to the output member (8) and including a plurality of clutch elements (24) retained against rotation relative to the housing (4), a plurality of separate spring elements (28) for adjustable preloading the clutch elements (24) against the counter-clutch elements (51) of the control element (18) for retaining the control element (18) against rotation upon application of the torque thereto until threshold of the torque is reached, and a common support element for supporting the spring elements and movable relative to the housing (4).

Abstract: It is an object of the invention to provide an effective technique for further enhancing the effect of reducing a reaction force inputted during hammering operation. Representative impact tool comprises a tool body, a hammer actuating member, a cylinder and a compression coil spring. The compression coil spring contacts the hammer actuating member and thereby positions the tool body with respect to the workpiece when the hammer actuating member is pressed against the workpiece and pushed rearward in advance of the hammering operation. In such position, the compression coil spring absorbs a reaction force that is caused by rebound from the workpiece and acts upon the hammer actuating member when the hammer actuating member performs the hammering operation on the workpiece. The cylinder is inserted into the tool body from the front along the axial direction of the hammer actuating member and thereby housed within a predetermined housing part of the tool body.

Abstract: An electrical power tool (1) includes a housing (10,20,30), an electrical motor (21), a motion conversion mechanism (36), a counterweight holding member (73), a counterweight (74), and support members (71,72). The electrical motor (21) is accommodated in the housing (10,20,30). The motion conversion mechanism (36) is configured to convert a rotary motion of the electrical motor (21) into a reciprocation motion. The counterweight holding member (73) extends in a direction perpendicular to directions of the reciprocation motion and is capable of being elastically deformed in the directions of the reciprocation motion. The counterweight (74) is supported by the counterweight holding member (73) and is capable of reciprocating in the directions of reciprocation motion together with the counterweight holding member (73). The support members (71,72) are positioned away from the counterweight (74) by a predetermined distance for supporting the counterweight holding member (73) to the housing (10,20,30).

Abstract: A handheld power tool with a rotating and/or hammering drive mechanism for a tool (11) that can be inserted into a tool receptacle (10) has a unit which transmit the rotation of a motor shaft (5) to an intermediate shaft (7), by which the tool receptacle (10) is set into a rotary motion and/or a hammering motion. A compact construction of the handheld power tool is attained by providing that the motor shaft (5) is coupleable or is coupled to the intermediate shaft (7) in one axis.

Abstract: A hammer drill has an elastic member without using a coil spring or the like on an intermediate spindle to compact a housing and decrease cost. The elastic member that elastically engages a clutch with a second gear and/or a boss sleeve includes first to third guide spindles, first and second interlock plates, and a coil spring. The guide spindles are provided in parallel with an intermediate spindle. The first and second interlock plates are provided at the first to third guide spindles and slidable integrally with the clutch by engaging with the clutch. The coil spring energizes the first and second interlock plates along the first to third guide spindles.

Abstract: A number of cam-operated devices such as power tools (10) are described, the tools having a rotary drive device (24) for rotating a drive shaft (36) having a cylinder cam (42) mounted thereon. A pair of cam followers (54) are located within a cam track (44) provided on the cam member (42), such that rotation of the cam (42) causes axial movement of the cam followers (54), which may be attached to a drive shaft (48) and a tool bit (12). A range of shapes of cam track (44) are described, each of which is non-sinusoidal in shape. Various embodiments of the invention provide non-sinusoidal cam tracks having forward or rearward throw sections which are respectively steeper, shorter, or provide greater acceleration of the cam followers than sinusoidal cam tracks of equivalent wavelength and amplitude. Related piston and cylinder devices and reciprocal drive devices are also described.

Abstract: A rotary spindle 4 for a power tool such as a hammer drill is disclosed. The spindle 4 comprises a first spindle part 402 for rotation about its longitudinal an axis by means of a motor and having an inwardly directed rim 406, and a second spindle part 404 for supporting a drill bit of the hammer drill and having an outwardly directed rim 410. The second spindle part 404 extends through an aperture 408 in the first spindle part 402 and rims 406, 410 cooperate with each other to prevent removal of the second spindle part 404 from the first spindle part 402. A circlip 414 locks the first and second spindle parts 402, 404 together and maintains o-rings 412 under compression.

Abstract: An electrical tool (1) includes an electric motor (3), a fan wheel (4) that is connected in torque-proof manner to a drive shaft (8) of the electric motor (3) disposed within a housing (2) that includes at least one air inlet aperture (6) and at least one air outlet aperture (7). The at least one air outlet aperture (7) is arranged axially apart from the fan wheel (4) with regard to the axis of rotation (10) of the drive shaft (8). An air guide baffle ring (11) encloses the fan wheel (4) coaxially and has at least one air duct (12) which leads to at least one air outlet aperture (7) located axially at a distance from the fan wheel (4) for cooling the electric tool (1).

Abstract: A rotary hammer includes a housing, a tool holder mounted on a front portion of the housing, and a motor mounted in the housing. The motor includes an armature shaft arranged substantially perpendicular to an axis of rotation of the tool holder and including toothing. A hammer mechanism is driven by the motor to generate impacts on a tool being held by the tool holder. The hammer mechanism includes a first intermediate shaft adjacent and substantially parallel to the armature shaft facing away from the tool holder. A rotation drive mechanism is driven by the motor to rotatingly drive a tool being held by the tool holder. The rotation drive mechanism includes a second intermediate shaft adjacent and substantially parallel to the armature shaft facing the tool holder. The toothing of the armature shaft meshes with corresponding toothing on at least one of the first intermediate shaft and the second intermediate shaft.

Abstract: A power tool having a rotary impact mechanism and a mode change mechanism. The impact mechanism is driven by an output member of a transmission and includes a hammer and an anvil. The mode change mechanism includes a mode collar that is movable between a first position, in which the mode collar directly couples the hammer to the transmission output member to inhibit movement of the hammer relative to the spindle, and a second position in which the mode collar does not inhibit movement of the hammer relative to the spindle. A power tool having an impact mechanism with an external adjusting member that can be moved to vary a trip torque of the impact mechanism is also provided.

Abstract: An impact mechanism includes a shaft, a hammer and an anvil coupled to the hammer. The shaft has a first helical groove and the hammer has a second helical groove. A ball is received in the first and second helical grooves to rotationally couple the hammer to the shaft and permit axial travel of the hammer relative to the shaft. An axial stop inhibits axial travel of the hammer along a first travel path and permits axial travel of the hammer along a second travel path. The axial stop includes first and second stop members, the first and second stop members having a first relative position to inhibit axial travel of the hammer and a second relative position to permit axial travel of the hammer.

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

Abstract: An electrical power tool includes a housing, an electrical motor, a motion conversion mechanism, a weight-supporting member, a counterweight, and a first supporting member and a second supporting member. The first supporting member and the second supporting member are each provided on the housing for supporting the weight-supporting member to the housing. The weight-supporting member has a first connecting part and a second connecting part supported by the first supporting member and the second supporting member, respectively; and an elastically deforming part. The elastically deforming part is positioned between the first connecting part and the second connecting part and has a mounting part for mounting the counterweight. The elastically deforming part includes a portion having a smaller cross-sectional area than each cross-sectional area of the first connecting part and the second connecting part.

Abstract: A hand-held drill hammer has a housing, a shaft (12) connected to a drive shaft (30), and a lifting bearing (14). The lifting bearing (14) is supported and the shaft (12) for converting rotary motion into a reciprocating motion. In a first switching configuration, a percussion drive connection exists between the shaft (12) and the lifting bearing (14). In a second switching configuration, the percussion drive connection is interrupted. The lifting bearing (14) may be fixed with respect to a reference system of the housing in the second switching configuration.

Abstract: An impact motorized wrench includes a tool-holder shaft arranged on a front side of the wrench and pivoting around a rotation axis, a rotary motion producing motor unit arranged on a rear side of the wrench opposite the front side and an operating member to operate the motor unit, a drive unit with a percussion mechanism being arranged between the motor unit and the tool-holder shaft. The motor unit, the drive unit and the percussion mechanism together form a base body of the wrench and the wrench includes two gripping handles attached to the base body, both being of elongated shape and transversally spaced apart relative to their longitudinal extensions. The handles define a common gripping plane tangential to both handles, which plane extends transversally to the rotation axis. The operating member is associated to one of the two handles.

Abstract: A portable power tool includes a housing, and an impact mechanism movably supported in the housing and having a front opening for receiving a working implement and a hammer piston for delivering hammer blows to the working implement. The impact mechanism is supported in the housing by a pivot device in a point located between the forward and rear ends of the impact mechanism and allowing longitudinal and pivotal movements but preventing in the support point radial and rotational movements of the impact mechanism relative to the housing. A resilient device is located at a distance from the pivot device and is arranged to bias the impact mechanism to a neutral position relative to the housing and to absorb vibration movements of the impact mechanism to protect the housing against such vibration movements.

Abstract: A rotating direction switching device for a pneumatic tool comprises an air inlet valve and a switch. The air inlet valve is driven to switch the rotating direction of the pneumatic tool by controlling the switch, thus simplifying the operation of switching between the clockwise mode and counterclockwise mode, and facilitating the operation by a single hand. Especially, no matter users who are right hand or left hand dominated could easily operate the pneumatic tool.

Abstract: An impact mechanism comprises a drive motor engaging member and a tool bit retaining member rotatably inter-connected therewith. The tool bit retaining member has a main body portion, an anvil portion securely attached thereto for co-rotation therewith, and a tool bit retaining portion securely attached thereto for co-rotation with the main body portion. A hammer member is mounted on the drive engaging member for movement between an anvil contact position wherein force is transmitted from the hammer member to the anvil portion, and a release position whereat the hammer member is temporarily removed from the anvil portion. A spring biases the hammer member to the anvil contact position. In use, the hammer member to move from its anvil contact position towards its release position, wherein the hammer member is propelled by the spring and the rotation of the drive engaging member to impact on the anvil portion.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in a power impact tool that linearly drives a tool bit by using a swinging mechanism. According to the invention, a representative power impact tool is provided with a motor, a rotating shaft, a swinging member, a tool driving mechanism and a counter weight. The swinging member is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft. The counter weight is disposed in a region higher than a lower end region of the swinging member in the vertical direction to intersect with the axis of the rotating shaft, and a lower end of the counter weight is connected to the lower end region of the swinging member.

Abstract: A hand-held hammer drill has a housing, a tool spindle rotatingly driving a tool, a hammer action percussion-driving the tool, a swash plate drive driving the hammer action, and a countershaft driving as needed the tool spindle and the hammer action. A first bearing and an axial bearing are provided. The hub is rotatably supported in a cantilevered arrangement by the first bearing in the housing and coaxially surrounds the countershaft. The hub has a free cantilevered end and the axial bearing is disposed on the free cantilevered end, wherein the axial bearing axially supports the countershaft and has radial play relative to the countershaft.

Abstract: A percussion mechanism for a repetitively hammering hand power tool in the form of a rotary hammer has a striker movable axially forward and backward in a guide barrel and imparting impacts directly and without any intermediate parts to an end section of a tool bit that is insertable into the hand power tool, a device that exerts pressure on the striker, by which the striker is capable of being set into a forward motion in the direction of the tool bit, a blocking element, with which the striker is blockable in its forward motion, and the striking frequency of the striker is adjustable by controlling the blocking time of the blocking element, so that the striking frequency of the striker depends on how long the blocking element blocks the forward motion of the striker.

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

Abstract: An impact mechanism includes a shaft, a hammer and an anvil coupled to the hammer. The shaft has a first helical groove and the hammer has a second helical groove. A ball is received in the first and second helical grooves to rotationally couple the hammer to the shaft and permit axial travel of the hammer relative to the shaft. An axial stop inhibits axial travel of the hammer along a first travel path and permits axial travel of the hammer along a second travel path. The axial stop includes first and second stop members, the first and second stop members having a first relative position to inhibit axial travel of the hammer and a second relative position to permit axial travel of the hammer.

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

Abstract: The invention relates to a tool holder for a hand-held drill, especially a hammer drill. Said tool holder comprises an especially one-piece, rotatably driven accommodating cylinder (34) with a recess (60) for a shank part of an insertable tool, said recess (60) being open on both front ends and being defined in between by an inner peripheral surface (62) of the accommodating cylinder (34). The inner peripheral surface (62) of the accommodating cylinder (34) has at least six planar peripheral sections (62n to 62u) in the peripheral direction, adjacent peripheral sections (62n, 62o; 62p, 62q; 62r 62s; 62t, 62u) forming respective angles of 120 degrees between them.

Abstract: The object is to provide a hammer drill having an elastic means without using a coil spring or the like on an intermediate spindle, and being capable of compacting a housing and decreasing cost. The elastic means for elastically engaging a clutch 35 with a second gear 30 and/or a boss sleeve 31 includes first to third guide spindles 47 to 49, first and second interlock plates 41 and 42, and a coil spring 50. The guide spindles 47 to 49 are provided in parallel with an intermediate spindle 25. The first and second interlock plates 41 and 42 are provided at the first to third guide spindles 47 to 49 and slidable integrally with the clutch 35 by engaging with the clutch 35. The coil spring 50 energizes the first and second interlock plates 41 and 42 along the first to third guide spindles 47 to 49.

Abstract: Disclosed is a handle including a grip element and a fastening element situated on the grip element; the fastening element protrudes at least partway into the grip element and is guided in the grip element with a radial play. The handle is characterized by means of at least one damping element that is situated on the grip element so that it functions as a stop for limiting the radial play of the fastening element in the grip element.

Abstract: An impact tool comprising a motor, a hammer 8 that is rotated and axially moved by a drive force of the motor, an anvil 3 that repeats engagement/disengagement from the hammer 8 accompanying rotation and axial movements of the hammer 8, and a tip tool 4 mounted to the anvil 3, the anvil 3 comprising a first split piece 3A, which includes pawls 3c (first concave-convex part) on an opposite side to the hammer and repeats engagement/disengagement from the hammer 8, a second split piece 3B, which includes pawls 3f (second concave-convex part) engageable with the pawls (first concave-convex part) 3c of the first split piece 3A in a direction of rotation, and to which the tip tool 4 is mounted, and a rubber damper (elastic body) 13 interposed between the first and second split pieces 3A, 3B to prevent direct contact between the pawls (first concave-convex part) 3c and the pawls (second concave-convex part) 3f in the direction of rotation and in an axial direction.

Abstract: A powered hammer includes a housing, a tool holder coupled to the housing and configured to hold a tool, a motor within the housing, a cylinder disposed within the housing, and a piston slideably mounted within the cylinder. A drive mechanism converts rotary output of the motor into a reciprocating motion of the piston. The drive mechanism includes a crank shaft rotationally driven by the motor, a drive pin eccentrically mounted on the crank shaft, and a con rod with a first end connected to the drive pin and a second end connected to the piston. A ram is slideably mounted forward of the piston that is reciprocatingly driven by the piston. A beat piece is slideably mounted forward of the ram. The beat piece is repetitively struck by the reciprocating ram, which in turn repetitively strikes an end of the tool when held in the tool holder to transfer the momentum of the ram to the tool. Lubrication fluid covers at least part of the drive mechanism.

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

Abstract: A pneumatic rotary tool has a housing formed primarily from plastic so that the weight and price of the tool are substantially reduced. The air motor is formed for economic assembly while permitting greater structural stability should the housing deflect under an impact. The tool includes a torque selector which controls the amount of pressurized air allowed to enter the air motor, thereby controlling the torque output of the motor. The user may adjust the torque selector to a number of set positions which correspond to discrete torque values. The tool additionally incorporates early and late stage exhaust ports, so that backpressure within the air motor does not slow motor rotation or decrease tool power.

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

Abstract: A hand-held hammer drill has a housing, a tool spindle rotatingly driving a tool, a hammer action percussion-driving the tool, a swash plate drive driving the hammer action, and a countershaft driving as needed the tool spindle and the hammer action. A first bearing and an axial bearing are provided. The hub is rotatably supported in a cantilevered arrangement by the first bearing in the housing and coaxially surrounds the countershaft. The hub has a free cantilevered end and the axial bearing is disposed on the free cantilevered end, wherein the axial bearing axially supports the countershaft and has radial play relative to the countershaft.

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

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

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

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

Abstract: A reciprocating drive mechanism for a striker in a hammer, a rotary hammer, or a power drill having a hammer action, includes a sinusoidal cam channel formed on a drive member and a cam follower, in the form of a ball bearing, attached to a driven member which, due to the interaction of the cam and cam follower, results in a reciprocating movement of the driven member. Both the drive member and driven member can be rotatingly driven by a motor, their relative speeds resulting in the reciprocating movement of the driven member. The driven member is connected to the striker either via a mechanical helical spring or an air spring.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in a power impact tool that linearly drives a tool bit by using a swinging mechanism. According to the invention, a representative power impact tool is provided with a motor, a rotating shaft, a swinging member, a tool driving mechanism and a counter weight. The swinging member is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft. The counter weight is disposed in a region higher than a lower end region of the swinging member in the vertical direction to intersect with the axis of the rotating shaft, and a lower end of the counter weight is connected to the lower end region of the swinging member.

Abstract: A pneumatic tool is operable with a single hand. The pneumatic tool includes a shell defining a first chamber and a second chamber. The second chamber includes intake and outlet apertures in communication with the first chamber. A cylinder is in the first chamber. A controller is movable in the second chamber between a first position and a second position. The controller includes a first groove and a second groove. In the first position, the first groove communicates with the intake aperture for directing pressurized air to drive the cylinder in a first direction. In the second position, the second groove communicates with the intake aperture for directing pressurized air to drive the cylinder in a second direction. A cover seals the first chamber and the second chamber. The cover defines an opening through which the controller extends from the second chamber so that the controller can be moved.