Abstract: A method and apparatus for using a plurality of impact dampening discs composed of a closed cell polyurethane foam composite with polyborodimethylsiloxane as a dilatant non-Newtonian fluid dispersed through a foam matrix in a downhole setting tool to absorb the energy released during setting operations.

Abstract: A hammer drill includes, in a cylinder accommodated in a housing, a piston configured to advance and retract and an impact element to operate together with the piston with an air chamber interposed therebetween, and a bit mounted in a front part of a tool main body so that an impact operation can be transmitted to the bit by advancing and retracting movement of the impact element. Vent holes are provided in the cylinder, and configured to discharge air in the air chamber to outside of the cylinder, and to introduce the air outside the cylinder into the air chamber by the movement of the piston. One of the vent holes is located at a center of an upper half of a periphery of the cylinder and the other vent hole is located in a lower half of the periphery of the cylinder.

Abstract: A power tool is disclosed. The power tool has a striker, which is guided along an axis in a guide tube. A pneumatic chamber has a volume which varies with a movement of the striker. The pneumatic chamber is closed by the striker, the guide tube and a valve device. The valve device has in a flow channel a sealing element that is moveable between two positions in a bearing along the axis. The flow channel has a first cross-sectional area in a first of the two positions of the sealing element adjacent to a first mating surface of the bearing, and the flow channel has a second cross-sectional area in a second of the two positions of the sealing element adjacent to second mating surface of the bearing offset from the first mating surface along the axis. The second cross-sectional area is greater than the first cross-sectional area.

Abstract: Disclosed is a hydraulic breaker.

Abstract: A pile driving system for driving a pile. The pile driving system comprises a housing assembly, a hammer, a helmet member, and a lifting system. The housing assembly defines at least one vent opening is arranged at a first vent location along the drive axis, and at least one vent opening is arranged at a second vent location along the drive axis. When the hammer drops and is above the first vent location, ambient air flows from the main chamber through the vent openings formed at the first and second vent locations. When the hammer is below the first vent location and above the second vent location, ambient air flows from the main chamber through the vent openings formed at the second vent location. When the hammer is below the second vent location, air within the main chamber is compressed to preload the helmet member.

Abstract: A rock drilling machine equipped with an axial bearing having at least one axial piston for setting the axial position of a drill shank and for damping stress pulses returning from the rock. The axial bearing includes a module that is detachable in one piece from one installation direction. The axial bearing module includes all necessary seals, bearing surfaces, and a module frame. Supporting forces caused by the operation of the axial bearing are transmitted of support members in the module frame directly to the body of the rock drilling machine, which is a uniform piece at least at the axial bearing.

Abstract: A hammer drill equipped with a main body part; a drive motor; a motion conversion mechanism, and a vibration absorber which are housed in the main body part; and a handgrip which is provided as a continuation of the main body part at a position closer to the rear end side of the tool than the drive motor and used for gripping the tool. The vibration absorber is in a configuration where vibrations of the main body part are suppressed during a machining operation.

Abstract: A rotary hammer includes a motor, a spindle coupled to the motor for receiving torque from the motor, a piston at least partially received within the spindle for reciprocation therein, a striker received within the spindle for reciprocation in response to reciprocation of the piston, and an anvil received within the spindle and positioned between the striker and a tool bit. The rotary hammer also includes a retainer received within the spindle for selectively securing the striker in an idle position in which it is inhibited from reciprocating within the spindle, and an O-ring positioned between the retainer and the spindle. The O-ring is disposed around an outer peripheral surface of the anvil. The O-ring is compressible in response to the striker assuming the idle position. The compressed O-ring imparts a frictional force on the outer peripheral surface of the anvil to decelerate the anvil.

Abstract: A machine tool is disclosed. A magneto-pneumatic striking mechanism has a primary actuator arranged around an axis of movement and includes a first magnetic coil and a second magnetic coil. The striking mechanism has, on the axis of movement within the magnetic coils, a striker and a die. Furthermore, the striking mechanism has an air spring acting on the striker in a direction of impact. The air spring may be entirely or partially within the first magnetic coil. The air spring has a ventilation opening that is open to the environment if the striker is less than 10% of its stroke away from the die, and otherwise the ventilation opening is closed. An exchange of air with the environment is therefore only possible when the striker is near the die or is near the impact position.

Abstract: A power tool 1 including a bit socket 6 which is configured to hold a chiseling bit 7 so that the latter can move along an axis of movement 3. A magneto-pneumatic striking mechanism 2 includes a primary drive 22 that is arranged around the axis of movement 3 and that has a first magnet coil 46, a permanently and radially magnetizable ring magnet 42 and a second magnet coil 47 arranged consecutively in the striking direction 5. On the axis of movement 3, inside the magnet coils 46, 47, the striking mechanism 2 has a striker 4 and a striking block 13 arranged consecutively in the striking direction 5. An air cushion 23 acts upon the striker 4 in the striking direction 5.

Abstract: A hand-held machine tool includes a tool accept for mounting a chiseling tool on an operating axis. A pneumatic hammer mechanism includes an exciter, driven back and forth by a motor about a stroke between a dead point distant from the tool and a dead point near the tool, a hammer moved back and forth on the operating axis between a reversal point distant from the tool and a point of impact, and a pneumatic chamber sealed by the exciter and the hammer, which couples the movement of the hammer to the movement of the exciter. A damping device increases the pressure in the pneumatic chamber when the exciter during its motion in the direction to the dead point distant from the tool has approached to less than half the stroke to the dead point distant from the tool.

Abstract: A hand-held power tool has a pneumatic striking mechanism (6). The striking mechanism (6) has a motor-driven exciter (12), a striker (13) and a pneumatic chamber (15) arranged along a working axis (10) between the exciter (12) and the striker (13). At least 20% of the volume of the pneumatic chamber (15) is filled with a monoatomic gas.

Abstract: A hand-held machine tool includes a tool accept for mounting a chiseling tool on an operating axis. A pneumatic hammer mechanism includes a hammer mobile on an operating axis, an exciter, and a pneumatic chamber sealed by an exciter and the hammer, which couples the movement of the exciter to the hammer. The exciter is driven by a motor and moves back and forth between a frontal dead point distant from the tool and a dead point near the tool. A damper device includes a supercharger and a controlled outlet valve. The controlled outlet valve allows air to flow from the supercharger into the pneumatic chamber when the exciter is in the proximity of the dead point distant from the tool.

Abstract: A drop hammer for driving a pile comprising a ram member supported within a housing chamber for movement relative to the housing member between the lower position and the upper position and a lifting system for moving the ram member from the lower position to the upper position. When the lifting system raises the ram member above a preload position, ambient air substantially freely flows into and out of the housing chamber through a vent port. When the ram member falls below the preload position, fluid is prevented from flowing through the vent port such that ambient air within a preload chamber portion of the housing chamber compresses to create a preload force that is transmitted to the pile. When the ram member moves into the lower position, an impact force generated by the ram member is transmitted to the pile.

Abstract: Rock drilling machine (10) comprising a piston that is arranged to move back and forth in a chamber (12a, 12b) when the rock drilling machine (10) is in use, a cavitation-sensitive component (14), and an oil channel that is arranged to extend between the chamber (12a, 12b) and said cavitation-sensitive component (14). The oil channel comprises a series of restrictions (18) and oil volumes (20) to hinder the movement of cavitation bubbles through said oil channel.

Abstract: A drop hammer for driving a pile comprising a ram member supported within a housing chamber for movement relative to the housing member between the lower position and the upper position and a lifting system for moving the ram member from the lower position to the upper position. When the lifting system raises the ram member above a preload position, ambient air substantially freely flows into and out of the housing chamber through a vent port. When the ram member falls below the preload position, fluid is prevented from flowing through the vent port such that ambient air within a preload chamber portion of the housing chamber compresses to create a preload force that is transmitted to the pile. When the ram member moves into the lower position, an impact force generated by the ram member is transmitted to the pile.

Abstract: A handheld tool with a pneumatically operated linear oscillating drive is provided. The handheld tool has a motor housing and a piston movable in the motor housing, which separates the two working chambers of the motor housing from one another. A piston crown faces toward one chamber of the two working chambers, with a compressed air supply line toward the motor housing and a slide valve, which controls an alternating supply of compressed air to one and the other of the two working chambers, and with an exhaust air opening in the motor housing. The handheld power tool is distinguished in that the piston additionally has a piston skirt facing toward the other chamber of the two working chambers.

Abstract: A recoilless hammer comprising a moil supported for reciprocal movement along a hammer axis of a housing, a piston moveable within the chamber of an elongate tube extending from the rear of the housing such that it may strike the moil. In a rest position the piston is held forward against the moil by a low pressure air supply delivered from the aft end of the chamber, and the piston is retracted to a charged position at the aft end of the chamber by delivery of high pressure air to act on the fore portion of the piston. Upon actuation of a trigger mechanism, air is vented from the fore end of the chamber to atmosphere causing a pressure unbalance of low magnitude across the piston, such that it accelerates towards and strikes the moil. The chamber is of a length to enable a high energy blow with minimal piston acceleration recoil when the hammer is manually held and operated.

Abstract: A drop hammer for driving a pile. The drop hammer of the present invention comprises a housing member, a ram member, a helmet member, and a lifting system. The housing member defines a housing chamber and a vent port defining a preload position. The ram member is supported for movement within the housing chamber. When the lifting system raises the ram member above the preload position, ambient air substantially freely flows into and out of the housing chamber through the vent port. When the ram member falls below the preload position, ambient air within a preload chamber portion of the housing chamber compresses to apply a preload force on the inner portion of the helmet member. When the ram member moves into the lower position, the ram member impacts the helmet member to force the helmet member from the rest position to the impact position, thereby driving the pile.

Abstract: A power tool according to the invention includes a dynamic vibration reducer having a body, a weight and elastic elements. The body is formed by a plurality of cylindrical members which are coaxially disposed to face each other. The elastic elements exert biasing forces on the cylindrical members such that the cylindrical members are held apart from each other. The cylindrical members are fixed to the tool body side under the biasing forces of the elastic elements. Venting members for forced vibration are provided on the cylindrical members and protrude radially outward from the cylindrical members, respectively. The venting members are mounted by inserting into venting member mounting parts on the tool body side in a direction transverse to the longitudinal direction of the cylindrical members. At least one of the venting members can move with respect to the cylindrical member in the longitudinal direction.

Abstract: A hand-held power tool includes a work spindle (4)in which a chuck (3) for receiving an axially displaceable, within limits, percussion working tool (2), is mounted on. The work spindle (4) having a coaxial die (5) located in its interior for imparting blows to the percussion working tool (2). At least one cooling air channel (7) extends in an outer housing (6) radially outwardly of the work spindle and opens into a chuck free space (8) which adjoins the work spindle (4). The at least one cooling air channel (7) communicates with the interior of the work spindle through an opening (10, 10?) formed in the work spindle. A seal (9, 9?) completely flowtight seals the free space (8) outwardly.

Abstract: A recoilless hammer comprising a moil supported for reciprocal movement along a hammer axis of a housing, a piston moveable within the chamber of an elongate tube extending from the rear of the housing such that it may strike the moil. In a rest position the piston is held forward against the moil by a low pressure air supply delivered from the aft end of the chamber, and the piston is retracted to a charged position at the aft end of the chamber by delivery of high pressure air to act on the fore portion of the piston. Upon actuation of a trigger mechanism, air is vented from the fore end of the chamber to atmosphere causing a pressure unbalance of low magnitude across the piston, such that it accelerates towards and strikes the moil. The chamber is of a length to enable a high energy blow with minimal piston acceleration recoil when the hammer is manually held and operated.

Abstract: A shock-absorbing element is disposed frontward of an interjacent element within a housing of an impact tool, and a washer is disposed rearward of and adjacent to the shock-absorbing element. The interjacent element is configured to come in contact with the washer when the interjacent element is caused to advance by an impactor's strike under no-load conditions. A sleeve disposed rearward of and adjacent to the washer is configured to position the shock-absorbing element and the washer, and to allow the interjacent element to move rearward and frontward inside the sleeve.

Abstract: A pile driving system for driving a pile. The pile driving system comprises a housing assembly, a hammer, a helmet member, and a lifting system. The housing assembly defining a drive axis and a plurality of vent openings. At least one vent opening is arranged at a first vent location along the drive axis, and at least one vent opening is arranged at a second vent location along the drive axis. The lifting system raises the hammer during each cycle. When the hammer drops and is above the first vent location, ambient air flows from the main chamber through the vent openings formed at the first and second vent locations. When the hammer drops and is below the first vent location and above the second vent location, ambient air flows from the main chamber through the vent openings formed at the second vent location. When the hammer drops and is below the second vent location, air within the main chamber is compressed to preload the helmet member prior to contact between the hammer and helmet member.

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 hand-held power tool (1) includes a linear motor (2) having a rotor (3) which is movable along a percussion axis (A) in an axially limited manner between two reversal points (W) and which can be driven by the striking piston (5) of the power tool with the intermediary of an air spring (4), sensors designed for determining the actual state of the rotor (3) and connected to a computer (9) connected via power electronics (33) to at least one field coil (10) of the linear motor (2), with the rotor (3) being displaced against a contact element (11a, 11b) at least at one reversal point (W) and being pressed against the contact element electromagnetically; and a control process for the hand-held power tool.

Abstract: A pressure-fluid-operated percussion device includes a frame allowing a tool to be arranged movably in its longitudinal direction. Pressure liquid is fed to the percussion device and returned to a pressure liquid tank. A stress pulse is produced in the tool utilizing pressure of the pressure liquid. A pressure liquid source maintains pressure in the working pressure chamber. Pressure liquid is intermittently fed to the percussion device such that the pressure liquid pushes a transmission piston into a predetermined backward position. Pressure liquid is alternately discharged rapidly from the percussion device so that the pressure of the pressure liquid in the working pressure chamber and the pressure liquid flowing from the pressure liquid source pushes the transmission piston towards the tool, generating a stress pulse in the tool.

Abstract: An impact force is transmitted to a tip end tool due to the changes of the air pressure within an air chamber generated by the reciprocal operation of the piston within a striker. The attachment portion of a tip end tool holding member for holding the tip end tool to a cylinder casing is sandwiched between buffers disposed in the two directions of the axial direction of the tool thereby to elastically support the tip end tool holding member to be movable in the two directions of the axial direction of the tool.

Abstract: The present invention relates to a method for controlling a rock drilling process, in which an impulse-generating device comprising an impact element transmits a shock wave to a tool connected to the impulse-generating device, whereby a portion of the energy of the shock wave is transmitted to the rock by means of the tool and a portion of the energy of the shock wave is reflected and brought back to the impulse-generating device as reflected energy. The method comprises steps of generating at least one parameter value representing the reflected energy, and regulating the interaction of said impact element with said tool at least partially based on said value or values to control the rise time and/or length of said shock wave. The invention also relates to a regulation device, an impulse-generating device and a drilling rig.

Abstract: An air spring hammer device that includes a drive piston, moving axially back and forth, with a front face of hollow embodiment and a hammer piston moving in said hollow. A ventilation slot is embodied in a guide wall of the drive piston. The drive piston may be guided in a guide tube. The guide tube comprises several idle openings. A moving control element is arranged on the exterior of the guide tube, in which control openings, corresponding to the idle openings, are provided. In an idle operating mode, the control element is in an open position, via which the ventilation slot, the idle openings and the control openings can be brought into connection with the environment.

Abstract: A tool (12) has a body (14) having an opening (16) forming a barrel (18) which has a top and a bottom (20 and 22), an opening (30) at the bottom (22), and a pressure input (44) for fluid communication. The barrel (18) receives a piston (24) and a magnet (23) which is contiguous with the pressure input (44). An actuator pin tube (26) is received in the opening (30) at the bottom (22) of the barrel (18), and an actuator pin (38) is engaged in the tube (26). A second opening (28) may be disposed in the top (20). A kit (110) containing the tool (12), hose (94), cartridges (84) and a pump (P). A method for using the tool (12) is also contemplated hereby. Multiple tools (12) may be detonated at the same time by hooking them up to a manifold (95 or 95?).

Abstract: A drop hammer for driving piles. The drop hammer of the present invention comprises a housing member and a ram member. The housing member defines a housing chamber. The ram member is supported within the housing chamber for movement relative to the housing member between an upper position and a lower position. When the ram member moves into the lower position, the impact of the ram member drives the pile. When the ram member falls below a preload position between the lower and upper positions, fluid within a preload chamber portion of the housing chamber compresses as the ram member moves into the lower position.

Abstract: A percussion drill, and methods of using the same, including a shank in mechanical alignment with a piston-hammer and a valve in fluid communication with the piston-hammer. The percussion drill further includes an internal hydraulic dampening system for reducing the velocity of the piston-hammer when the shank is forward of a power position relative to the velocity of the piston-hammer when the shank is in a power position. Preferably, the internal hydraulic dampening system includes mechanical alignment of a portion of the piston-hammer with a port in fluid communication with the valve, operable to reduce fluid flow into an area surrounding the valve when the piston-hammer is forward of its position relative to its normal operation.

Abstract: A pneumatic impact tool includes a housing, an accumulation chamber, and a piston. The housing defines a longitudinal passageway with a rear end and a front end and a passageway gas port. The accumulation chamber has a accumulation chamber gas port connectable to a gas supply and a inner gas port in fluid communication with the longitudinal passageway. The piston is inserted in the longitudinal passageway and slides between a rest position wherein the piston is juxtaposed to the rear end of the longitudinal passageway and an impact position wherein the piston is juxtaposed to the front end of the longitudinal passageway. The piston moves from the rest position to the impact position when gas is inserted in the longitudinal passageway through the passageway gas port and is propelled therebetween by pressurized gas contained in the accumulation chamber.

Abstract: A driving mechanism for a powered hammer having a motor and a tool holder includes a ram mounted for reciprocation in a guide tube section. The ram has a radially outwardly projecting sealing portion and an outer circumferential surface that defines a helically shaped vent channel running from a front end portion of the circumferential surface to a rear end portion of the circumferential surface and being interrupted by the sealing portion. A piston is driven in reciprocating motion of the motor such that an air cushion is generated in a space between the ram and the piston to cause an impact on the tool bit by movement of the ram towards the tool bit. The space between the ram and the piston is temporarily connected with ambient air through the helical vent channel and a recess in the wall of the guide tube section after causing the impact on the tool bit.

Abstract: A ground piercing tool as according to the invention has a front head assembly mounted on a bit shaft. A mid-portion of the bit shaft is mounted between front and rear chambers. Compressed fluid is supplied to the front chamber to form a gas spring that prevents the bit shaft from impacting against a front stop when it receives a blow from the striker. A valve is provided that includes a passage that permits communication between the front chamber and the rear chamber when the bit shaft is in a forwardmost position wherein it contacts the front stop. The valve permits compressed air to pass from the front chamber to the rear chamber, negating the gas spring when the bit shaft is in the forwardmost position.

Abstract: A percussion drill, and methods of using the same, including a shank in mechanical alignment with a piston-hammer and a valve in fluid communication with the piston-hammer. The percussion drill further includes an internal hydraulic dampening system for reducing the velocity of the piston-hammer when the shank is forward of a power position relative to the velocity of the piston-hammer when the shank is in a power position. Preferably, the internal hydraulic dampening system includes mechanical alignment of a portion of the piston-hammer with a port in fluid communication with the valve, operable to reduce fluid flow into an area surrounding the valve when the piston-hammer is forward of its position relative to its normal operation.

Abstract: A vibration reduction apparatus for use with a hammer tool having a hammer piston is disclosed. The hammer piston is caused to reciprocate in the cylinder by rotation of a gear wheel and crank drive. A cam is mounted around the gear wheel, a counterweight surrounds the piston cylinder, and a cam follower is provided on the counterweight. The cam follower on the counterweight is urged into contact with the cam by a biasing element. The external profile of the cam is such that rotation of the gear wheel causes oscillation of the counterweight in antiphase to motion of the hammer piston to counteract vibrations produced by operation of the hammer action of the tool. A mechanism is provided to deactivate the vibration reduction apparatus when the hammer action of the tool is deactivated.

Abstract: The invention relates to a hand-held working tool, having a first unit, powered by a vibration on operation and a second unit which may be displaced relative to the first unit. A vibration isolation device is arranged between the first and second unit, having an actuator, for generation of a control force. An operational force acting in the working direction (A) between the first and the second unit may be at least partly compensated by the control force. The actuator is pneumatically operated and comprises an air spring for vibration isolation. A working piston in an air spring percussion device on the working tool serves to supply compressed air for the air spring. Alternatively, the compressed air can be supplied by the oscillating relative movement between the first unit and the second unit.

Abstract: A device (1) which includes an elongate body (2) with a movable mass (3) arranged for sliding movement within the body (2), the element (4) being arranged to decelerate toward an end of the body (2) in order to impart forward movement thereto, via momentum transfer, and being arranged to accelerate away from said end in order to further drive the body (2) forward, again using momentum transfer.

Abstract: A boring and/or percussion hammer comprises an electrodynamic linear drive and a pneumatically damped percussion mechanism which is provided with a drive piston driven by the linear drive during the reciprocating movement thereof, an impact piston and a pneumatic spring arranged between the drive and impact pistons. An air-supply device comprises a pumping element, which is linearly forth and back movable for generating airflow. The pumping element is connected to the drive piston in such a way that the movement thereof is transmitted to said pumping element, thereby the cooling air is transported by an air channel for cooling heat generated elements.

Abstract: A driving mechanism for a powered hammer having a motor and a tool holder includes a ram mounted for reciprocation in a guide tube section. The ram has a radially outwardly projecting sealing portion and an outer circumferential surface that defines a helically shaped vent channel running from a front end portion of the circumferential surface to a rear end portion of the circumferential surface and being interrupted by the sealing portion. A piston is driven in reciprocating motion of the motor such that an air cushion is generated in a space between the ram and the piston to cause an impact on the tool bit by movement of the ram towards the tool bit. The space between the ram and the piston is temporarily connected with ambient air through the helical vent channel and a recess in the wall of the guide tube section after causing the impact on the tool bit.

Abstract: An axial bearing includes a first piston and a second piston. Axial contact surfaces between the pistons are arranged in the same pressure space. The same pressure fluid fed to the axial bearing acts on the contact surfaces and on working pressure surfaces of the pistons. A rock drilling machine is also provided with such an axial bearing.

Abstract: A percussion power tool apparatus includes a body relative to which an impacting tool is moved to effect an impacting operation, the apparatus further including an operating member by means of which an operating load is applied in an operating direction to the apparatus, a support structure for the operating member including a piston received in a cylinder, the operating load acting to move the piston inwardly of the cylinder whilst such movement is resisted by fluid pressure in the cylinder at one side of the piston, relative movement between the piston and the cylinder being permitted in response to vibrations arising in the body and/or impacting tool, by controlling fluid flow between the one side of the piston and a pressurised fluid support system.

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: The non-axial force exerted on a pneumatic tool by a non-axial air supply is balanced to allow for uniformly radially distributed compliance forces on the tool. An annular air ring is disposed around the pneumatic tool, covering an air inlet port. Air is supplied by any route to a first air passage that supplies the air to the interior of the annular air ring, exerting a force on the annular air ring. Air flows in the annular space of the air ring, entering the tool air inlet port to drive the pneumatic tool. One or more second air passages are connected to the annular air ring in an even radial distribution. Each second air passage is connected to the air source, or terminates in an air blockage, creating a column of pressurized air that exerts a force on the annular air ring equal to the first air passage. The forces exerted on the air ring are thus balanced with respect to the axis of the tool.

Abstract: A method of generating a stress pulse, and an impact device. In the method, pressure fluid is fed as pressure pulses to a working chamber residing between the frame of the impact device and a tool such that the resulting force presses the tool towards the material to be processed. The impact device comprises a working chamber and device for conveying pressure fluid as pressure pulses thereto such that a force is produced between the frame of the impact device and a tool to press the tool towards the material to be processed.

Abstract: An air chamber is formed in a cylinder between a piston and a striking member. The cylinder is formed with at least one through-hole for providing fluid communication between the air chamber and an outside of the cylinder. A switching mechanism switches operation modes between a first operation mode and a second operation mode. In the first operation mode, the at least one through-hole is closed when the working tool is moved toward the another end and, when the at least one through-hole is closed, reciprocating motion of the piston generates pressure changes in the air chamber, allowing the striking member to transmit a striking force to a working tool. In the second operation mode, the at least one through-hole is constantly open, prohibiting the striking member from transmitting a striking force to the working tool.

Abstract: It is an object of the present invention to provide a power tool having a further improved vibration reducing performance. The representative power tool may comprise a tool bit, an actuating mechanism, a dynamic vibration reducer. The actuating mechanism drives the tool bit linearly by means of pressure fluctuations so as to cause the tool bit to perform a predetermined operation. The dynamic vibration reducer has a weight that reciprocates under a biasing force of an elastic element to reduce vibration of the actuating mechanism. The weight may be driven by means of pressure fluctuations caused in the actuating mechanism. According to the invention, the weight of the dynamic vibration reducer can be actively driven by pressure fluctuations in the actuating mechanism for driving the tool bit. Therefore, regardless of the magnitude of vibration acting on the power tool, the dynamic vibration reducer can be forcedly and steadily operated.

Abstract: A pneumatic tool (20) for impacting a workpiece (22) is provided. The tool (20) comprises a casing (42) defining a chamber (48). A piston (54) is slidable within the chamber (48) along an operational axis (A). An exhaust valve (100) controlled by a pilot valve (200) slides the piston (54) by selectively introducing and releasing pressurized fluid into and out from the chamber (48). The pilot valve (200) includes a valve housing (202) defining a pilot chamber (204) with a plunger (206) slidable in the pilot chamber (204). The pilot valve (200) actuates the tool (20) by quickly releasing pressurized fluid from the exhaust valve (100) to atmosphere. The pilot valve (200) includes a spring-biased annular seal (214) that is releasable from a poppet seat (222) to perform this function.