Abstract: An electrically powered hammer comprising a hollow spindle within which spindle is reciprocatingly mounted a piston, a ram, a beatpiece having an increased external diameter mid-portion and located within the spindle between the ram and the tool or bit, a two part sleeve arrangement located within the spindle and including an increased internal diameter mid-portion for receiving the increased external diameter portion of the beatpiece and a reduced internal diameter forward and rearward portion for guiding the forward and rearward ends respectively of the beatpiece and where the sleeve arrangement includes a forward sleeve and a rearward sleeve which are both guided with tight radial tolerances and with a slight axial play within and by the spindle and the forward axial movement of the forward sleeve is limited by a reduced diameter portion of the spindle and the forward axial movement of the rearward sleeve is limited by the forward sleeve.

Abstract: A switch assembly (1) for centrally arranged operating mode selection for an at least partially rotary and percussion combination hand tool device (2) is comprised of a first switch sleeve (11) for the switchable percussion drive (6) and a second switch sleeve (12) for the switchable rotary drive meshing with a tool spindle (4) via a countershaft (3) and a switch accessory (10) connecting both switch sleeves (11, 12) together, whereby the countershaft (3) and a percussion drive shaft (5) of the percussion drive (6) are arranged directly adjacent and parallel in a common axially by extending zone (B) and rotationally-freely guide a driving gear pair (7) in direct meshing engagement with each other and which can be engaged by way of the switch sleeves (11, 12).

Abstract: A hammering electric hand tool device with idle strike cutoff for a pneumatic striking mechanism with an axially fixed guide pipe and a hammer member striking in the interior of a rotatable tool holder, wherein the tool holder encloses the guide pipe on the radial outer side at least partially, at least in an axial, partial area, and the tool holder is mounted so as to be movable in an axially limited manner.

Abstract: A motor driven hammer comprising a tool holder and an air cushion hammering mechanism including a piston and a beat piece slideably located in a cylinder wherein reciprocation of the piston in the cylinder will cause the beat piece to hit a tool located in the tool holder, and further comprising an eccentric mass mounted for rotation about the axis of the cylinder and rotatingly driven by the motor via a gear arrangement so as to cause the bit mounted in the tool holder to be laterally diverted.

Abstract: A percussion electrical hand-held tool including a housing (10), a percussion element (2) located in the housing, and a planetary gear unit (5) located in the housing (10) for converting a rotational movement (&ohgr;) of the drive shaft (1) of the hand-held tool (8) into a reciprocating movement (&ugr;) of the percussion element (2), with the planetary gear unit (5) including a sun gear (6) changing of a setting (&agr;) of which provides for adjusting of an impact amplitude of the reciprocating movement (&agr;) of the percussion element (2), and control unit located in the housing (10) for adjusting the impact amplitude in accordance with a manual axial force applied to the handle of the hand-held tool (8).

Abstract: A first switching member, having a claw portion engageable with a claw portion of a first gear, is slidably mounted on a crank shaft without causing any relative rotation therebetween. A first urging member resiliently urges the first switching member so that the claw portion of the first switching member is engaged with the claw portion of the first gear. A second switching member, having a claw portion engageable with a claw portion of a second gear, is slidably mounted on an intermediate shaft without causing any relative rotation therebetween. A second urging member resiliently urges the second switching member so that the claw portion of the second switching member is engaged with the claw portion of the second gear.

Abstract: An electrical hand operated tool driving device (1), such as a hammer drill, a combination hammer or a chipping hammer, has an electropneumatic striking mechanism (2), for which a cooling medium (8), for cooling the striking mechanism (2), flows through a liquid-tight cooling medium duct (10, 11, 12, 13), which is disposed in a housing (7) of the tool driving device (1).

Abstract: An electrical hand operated tool driving device (1) for producing an at least partially impacting movement of a tool (11) with an air striking mechanism (2) and a no-load stroke disconnection, which scans the no-load stroke position (9) by a sensor (14) and evaluates it with an assigned control unit (15), and in the event of a no-load stroke, lowers the rpm of an energizing driving mechanism (3) over the control unit (15) to a previously fixed reduced rpm.

Abstract: A hammer drill 1 includes a barrel 2 containing a striking mechanism. The drill further includes a motor 4 with a motor shaft 6 encased in a motor accommodating chamber 19 which has an upper opening at which a baffle plate 20 is disposed. The baffle plate 20 includes a bottom portion 21 and a partition 22. The baffle plate 20 further includes a flange 23 that extends radially around the upper edge of the partition 22 except toward the front of the partition 22 with the outer edge of the flange 23 reaching the inner surface of the motor housing 3. Additionally, a generally horizontal slot 24 is formed at the front peripheral surface of the bottom portion 21 of the baffle plate 20. Moreover, a plurality of air inlets 27 are provided at the rear end of a housing handle 5 of the drill 1, whereas a plurality of air outlets 29 are provided at the bottom of the motor housing 3.

Abstract: An electrical hand-held tool for producing at least a percussion movement of a working tool and including an electrical drive, a first subassembly including a percussion mechanism (2) and a rotor (5) of the electrical drive and rotatable about a rotor axis (B) extending parallel to an oscillation path (I) of the first subassembly, and a second subassembly including a housing (6) in which the first subassembly is supported for a limited movement along a tool axis (A).

Abstract: A rotary hammer is provided which comprises a tool holder (2) and an air cushion hammering mechanism which comprises a cylinder (8′) having one end (8) that is connected to the tool holder, a piston (9), a ram (10) and a beat piece (21) slidably located in the cylinder so that reciprocation of the piston in the cylinder will cause the ram to reciprocate in the cylinder and thus cause the beat piece to hit a bit located in the tool holder. The ram (10) has an annular recess (31) in its peripheral surface at the end thereof nearest the piston (9), in which recess is located an annular seal (30). The annular seal has an annular seating flap (36) lying on the radially outwardly directed surface of the recess and an annular sealing flap (38) that is joined to the seating flap and extends between the radially outwardly directed surface of the recess and the inner wall of the cylinder (8′).

Abstract: The invention relates to a pneumatic impact mechanism for a paving breaker and/or hammer drill which is characterized by a drive piston (1) having air equalization slits (5) and an extremely reduced wall thickness of the guide sleeve (1a) thereof This leads to a distinct reduction of the vibrations during the no-load operation of the impact mechanism, whereby advantageous characteristics of the impact mechanism with regard to wear behavior and compactness can be retained.

Abstract: A rotary hammer which comprises a tool holder (2), an air cushion hammering mechanism which comprises a piston (9) and a beat piece (21) slideably located in a cylinder (8′) so that reciprocation of the piston in the cylinder will cause the beat piece to hit a tool located in the tool holder; and means for causing the cylinder to rotate in addition to, or instead of, reciprocation of the piston in order to cause a tool located in the tool holder to rotate. The piston (9) is formed from a plastics material and is sealed in the cylinder (8′) by means of an annular seal (27) that is located within an annular groove (26) in the piston. The annular seal has an inner diameter that is greater than the diameter of the radially outwardly directed surface of the groove, and the groove has an axial dimension that is greater than that of the annular seal, so that when the cylinder rotates about the piston (without reciprocation of the piston) the seal (26) will rotate with the cylinder (8′).

Abstract: A rotary hammer which comprises a tool holder (2), an air cushion hammering mechanism which comprises a piston (9) and a beat piece (21) slideably located in a cylinder (8′) so that reciprocation of the piston in the cylinder will cause the beat piece to hit a tool located in the tool holder; and means for causing the cylinder to rotate in addition to, or instead of, reciprocation of the piston in order to cause a tool located in the tool holder to rotate. The piston (9) is formed from a plastics material and is sealed in the cylinder (8′) by an annular seal (27) that is located within an annular groove (26) in the piston. The annular seal has an inner diameter that is greater than the diameter of the radially outwardly directed surface of the groove, and the groove has an axial dimension that is greater than that of the annular seal, so that when the cylinder rotates about the piston (without reciprocation of the piston) the seal (26) will rotate with the cylinder (8′).

Abstract: A hand drill including a housing (2), a rotary drive (8-15) arranged in the housing (2) for driving a chuck (6) provided at a front, in the drilling direction, end of the housing and in which a drill or a chisel tool is received, a compressed air-operated hammer mechanism having a pneumatic cylinder (22), a die member (15) for imparting axial blows to the drill or chisel tool, and a percussion piston (30) displaceable in the pneumatic cylinder 922) upon being impinged by compressed air for intermittently applying axial blows to the die member (15), and a reversing valve for connecting the hammer mechanism (22) with a source of compressed air, integrated in the percussion piston (30), and having a plurality of recesses and bores (46-52) alternatively operationally connectable with at least one inlet opening (23) and at least one discharge opening (24) of the pneumatic cylinder (22) for feeding the compressed air into the pneumatic cylinder (22) and for discharging the compressed air therefrom.

Abstract: A manually operable drilling tool (1) wiht dual impacting funtion has a housing (2) containing a first striking mechanism (16) for producing axial impacts to be transferred to a drilling or chiseling tool bit (7), clamped in a chuck (6) of the tool (1). Within the housing (2), a second striking mechanism (20) is arranged for producing axial impacts, the axial impacts of which have an impact energy and an impact frequency different from the impact energy and the impact frequency of the axial impacts produced by the first striking mechanism (16). The drilling or chiseling tool bit (7), clamped in the chuck (6), can be acted upon with axial impacts produced either by the first (16) or the second striking mechanism (20) or by both striking mechanisms together. The axial impact striking, mechanisms (16, 20) can also be switched off completely for use in wood or metal.

Abstract: A hammer drill (1) includes an intermediate shaft (13), a clutch ring (25), a second gear (20), and a boss (15) all mounted on the intermediate shaft (13). Also included are a rotatable change lever (40) and a clutch plate (31) which has lock claws (36). When the change lever (40) is fully rotated in the clockwise direction, the hammer drill (1) is placed in a drill-only mode where the clutch ring (25) meshes only with the second gear (20). When the change lever (40) is rotated approximately 45 degrees counterclockwise from the foregoing position, the hammer drill (1) is placed in a hammer drill mode, where the clutch ring (25) meshes with the second gear (20) and the boss (15). When the change lever (40) is rotated approximately another 45 degrees counterclockwise, the hammer drill (1) is placed in a neutral position where tile second gear (20) is disengaged from the clutch ring (25), with the clutch ring (25) remaining in mesh with the boss (15).

Abstract: A power-driven hammer has a tool holder a middle bore portion which is supported inside a housing and urged backward by a compression spring. The rear end of a large bore portion of the tool holder is slidably fitted into a spline ring which is secured to the front end of a middle housing. Spline grooves are formed in the inner periphery of the spline ring at its front end while spline gears are formed on the outer periphery of the large bore portion. When the spline grooves and the spline gears are engaged with each other, the tool holder, being urged backward, is locked with its rotation prohibited. This tool holder can be temporarily unlocked to allow its rotation by sliding a change ring cover forward and the tool holder itself, thereby disengaging the large bore portion from the spline ring.

Abstract: A double action pneumatic spring percussion mechanism has an air supply mechanism. A percussion piston is movable with a driving piston. In an air-supply position, ambient air is supplied through an air inlet to a front pneumatic spring. When the percussion piston and driving piston are moved accordingly relative to each other, a loading hole is opened, through which air under increased pressure can flow out of the front pneumatic spring into a rear pneumatic spring, ensuring an increase of pressure in the rear pneumatic spring. The air pressure increase in both pneumatic springs makes it possible to use the pneumatic spring percussion mechanism even in conditions of operation with a low ambient air pressure.

Abstract: A drilling and a percussion power tool and the tool holder, a housing, an air cushion percussion mechanism arranged in the housing and including a guiding tube, a piston reciprocating in the guiding tool, a striker reciprocating in the guiding tube, an air cushion chamber formed on the guiding tube between the striker and the piston, at least one control opening ventilating the air cushion chamber in an idling position of the percussion mechanism, a control part which in a percussion operation closes the at least one control opening for forming an air cushion in the air cushion chamber, and at least one additional opening formed in the guiding tube for ventilating of the air cushion chamber and arranged forwardly of the at least one control opening at a side of a tool so that in the percussion operation the at least one additional opening is covered by the striker.

Abstract: The invention concerns a drill hammer having an air cushion percussion mechanism with which an energizing bushing (24) is disposed concentric to the drill tool axis (10) and forms a cavity (26) containing the air cushion in which a percussion piston (28) can move back and forth, and with a wobble drive device (34) for moving the energizing bushing (24) back and forth in the direction of the drill tool axis (10), the rotation element (36) of which driving the nutating disk (42) being disposed for rotational drive parallel to the drill tool axis (10) at a separation therefrom. In order to increase the smoothness of running of the drill hammer, a weight (50) is disposed under restrictive guidance for linear back and forth motion parallel to the drill tool axis (10) in response to the action of the nutating disk (42), at that side of the nutating disk (42) lying diametrically across from the energizing bushing (24).

Abstract: A second pinion is rotatably supported around an intermediate shaft and slidable in an axial direction of the intermediate shaft. A pinion sleeve is fixed to the intermediate shaft. A first clutch mechanism selectively engages and disengages the second pinion with and from the pinion sleeve to selectively transmit and interrupt a rotational force of a motor to a tool attached on a front end of a hammer drill. A sleeve is supported around the intermediate shaft so as not to be rotatable about the intermediate shaft but slidable in the axial direction of the intermediate shaft. A motion converting member is rotatably supported around the intermediate shaft. The motion converting member converts the rotational force of the motor into the percussion force. A second clutch mechanism selectively engages and disengages the motion converting member with and from the sleeve to selectively transmit and interrupt the percussion force to the tool.

Abstract: A tool for drilling and/or chiselling has an axially extending guide tube (9) with at least one radially extending air passage (10) and a control body for selectively closing the air passage. The control body has the stop (30) interacting with a first stop shoulder (18) on a driving anvil (17). The control body can be displaced relative to the guide tube (9) opposite to the working direction of the tool against the biasing action of a spring (12) supported on a connecting sleeve (13) of the control body. The driving anvil (17) has a second stop shoulder (19) facing opposite to the working direction and interacting with a stop surface (20) facing in the working direction. The stop surface (20) is secured axially with the guide tube (9).

Abstract: A tool for drilling and/or chiseling has a striking mechanism (6) within a guide tube (9) for reciprocating a first piston (7) and, via an air cushion, for reciprocating a second piston (19) within the guide tube. The second piston drives a driving anvil (17) in the driving direction. Between the first and second pistons (7, 19) the guide tube (9) has a series of radially extending first air passages (10) arranged in a first plane (E1) extending perpendicularly of the driving direction. A control body can be shifted over the guide tube (9) and is connected to the driving anvil (17). The guide tube (9) has a second series of radially extending second air passages (11) therethrough arranged in a second plane (E2) spaced from the first plane (E1) at a distance (A) opposite to the driving direction.

Abstract: A rotary hammer operable in an idle mode and a hammer mode. The rotary hammer includes a housing, a barrel positioned in the housing and including a side wall having a port, a ram positioned within the barrel and axially movable relative to the barrel, and a seal supported on the mid-portion of the ram and forming a seal between the side wall and the ram. The seal has a range of motion relative to the barrel, and the port is located in the side wall such that the port is beyond the range of motion of the seal. The hammer further includes a tool supported by the hammer, and engagement of the tool with a workpiece moves the barrel relative to the housing and changes the hammer from the idle mode to the hammer mode. The hammer further includes a biasing member, such as a spring, biasing the hammer toward the idle mode.

Abstract: A percussive tool generates a reduced impact at the start of percussive operation following idling operation. The percussive tool has a cylinder containing a piston, an air chamber in front of the piston, and a striker disposed in front of the air chamber. A slide sleeve and a rimmed ring at the rear end thereof are fitted around the cylinder. The cylinder has formed therein an exhaust port and auxiliary ports in front of the exhaust port for placing the air chamber in communication with the atmosphere. When the slide sleeve is retracted, the exhaust port is closed by the rimmed ring. During percussive operation of the percussive tool, the auxiliary ports are always closed by the reciprocating striker and therefore not open to the air chamber. During idling operation, the striker takes an advanced position and opens the auxiliary ports, thereby placing the air chamber in communication with the atmosphere.

Abstract: A hammer mechanism (14) for a rotary drill (10) comprises a hollow piston (18), a drive (15,26) for effecting reciprocating motion of the piston (18) towards and away from an end portion (35) of a rotatable output spindle (13) of the drill (10) and a ram (21) adapted to slidably locate in a hollow portion of the piston (18). In use, reciprocating movement of the piston (18) is transferred to the ram (21) and the ram (21) periodically strikes the end portion (35) of the output spindle (13), thereby providing the hammer action of the drill. The hammer mechanism (14) also comprises a plurality of guide pins (27,28) fixed in position relative to a housing portion (11) of the drill (10), the piston (18) being provided with a plurality of guide cylinders (23,24) each one of which is adapted to cooperate with a corresponding one of the guide pins (27,27) so as to guide the reciprocating motion of the piston (18).

Abstract: A manually operable tool, such as a hammer drill, for drilling and/or removing material in at least one of brittle material and low ductile material, has a continuously rotatable chuck (8) and a motor driven striking mechanism (1) for transmitting impulse-like blows to a tool bit (9) held in the chuck (8). The tool includes members (5) for transmitting impulse-like blows composed of superimposed axially-directed blows and torsional blows to the tool bit (9) in the chuck for forming drilling blows. Further, an adaptor can be provided for attachment to the hammer drill containing the members (5) for affording the superimposed blows.

Abstract: A hammer drill has an aluminum cylinder non-rotatably mounted in a crank housing, a synthetic resin slide sleeve, and a tool holder. The latter two members are coaxially fitted over the front part of the cylinder. The slide sleeve is a cylindrical member slidably mounted between a large bore portion of the tool holder and the cylinder. A steel ring is mounted at the rear of the slide sleeve. The slide sleeve and the steel ring are urged in the forward direction by a compression spring interposed between a bevel gear and the steel ring. A first air chamber which is formed in the cylinder includes a plurality of air ports which are covered by the steel ring when the slide sleeve and steel ring are pushed in their respective rear positions by pressing a tool bit attached to the hammer against a work piece. A plurality of wide and narrow slits are formed in the front portion of the slide sleeve while a plurality of air passage holes are also formed in the large bore portion of the tool holder.

Abstract: A compressor piston divides a first compartment into two compression chambers, while a hammer piston divides a second compartment into two drive chambers, each of the compression chambers being connected to a respective one of the drive chambers to form a closed fluid system wherein reciprocation of the compressor piston causes cyclic compression and expansion of the fluid in the compression chambers and thus in the drive chambers, to effect a cyclic impacting of the hammer piston with a bit adapter connected to the drill bit. A mud motor rotates a shaft to drive an oscillator which reciprocates the compressor piston. The oscillator can comprise roller elements in the compressor piston in engagement with canted grooves in the shaft. While drilling mud drives the motor and then passes downwardly to flush the drill bit and the borehole, the drilling mud is isolated from the closed fluid system.

Abstract: A rotary hammer with a pneumatic hammer mechanism has a reciprocatable piston driven in a guide tube, which piston, through alternating development of overpressure and underpressure at its rear side, moves a ram forward to create an impact on the rear end of the bit and back again, the front side of the ram being connected to the surrounding air via at least one vent opening. The at least one vent opening is at least partially closeable to create a pressure countering the forward movement of the ram.

Abstract: The invention provides an improved intermediate housing incorporated in a power driven hammer drill, which is light in weight, easily and safely handled, and uncostly manufactured. The intermediate housing of the invention includes a bearing member and a cylindrical piston housing member which are integrally composed of a synthetic resin having high tenacity and excellent heat resistance and wear resistance. The intermediate housing further includes a plurality of ribs radially extending from the piston housing member to give a sufficient strength durable to a stress applied onto the piston housing member. In the intermediate housing thus constructed, the bearing member has at least one opening for feeding an air flow generated by a fan while the piston housing member includes at least one air conduit for circulating the air flow. This structure efficiently prevents overheat and thermal deformation of the piston housing member and the bearing member in continuous operation of the hammer drill.

Abstract: The percussion device which can be used as a hammer drill has a drive piston for driving an overhung percussion piston which is mounted between two air cushions. Depending on the percussion travel of the percussion piston, the percussion air cushion is reversed so that a respective partial quantity is passed around the percussion piston to the opposite side by a central bypass. A no-load bypass is also provided to vent the recoil air cushion to the percussion cushion for a no-load condition. A third bypass bridges the drive piston in the top dead center position to communicate an annular chamber to the rear of the drive piston with the percussion cushion.

Abstract: A power hammer drill includes a tool holder and an air cushion striking mechanism for driving a tool and including a striker, a reciprocating piston for displacing the striker, and an axially displaceable guide tube for guiding the piston. A device for holding the striker in a forward position thereof adjacent to the tool holder in an idling condition of the hammer drill is provided in the hammer drill. The device has a guide element fixed in the drill housing for guiding the guide tube. The guide tube has a control opening for venting the air cushion and which remains in open or closed condition dependent on axial position of the guide tube.