Abstract: A hydraulic rotary percussive hammer drill includes a body containing a reciprocating percussion piston sliding under the effect of a main hydraulic supply circuit, this main circuit also being intended to cause the sliding of a roughly annular abutment piston housed in a cavity of the body, and having, on the one hand, a front face in contact with a shank and intended to place this shank a predetermined distance away from the percussion piston and, on the other hand, a rear face facing a rear wall of the cavity, characterized in that an external hydraulic supply circuit is able, when the main circuit is shut down, to introduce fluid under pressure between the rear face of the abutment piston and the rear wall of the cavity so as to maintain a space between these items.

Abstract: A ground piecing tool includes a housing and an air distributing mechanism that reciprocates a striker to impact a chisel shaft in response to a supply of compressed fluid including a fluid inlet tube mounted in the bore of the striker having a radial port, a rear end of the inlet tube being in communication with the distributing mechanism, wherein the housing and chisel shaft cooperate to define a front chamber that decreases in volume as the chisel moves forward relative to the housing, and wherein the chisel shaft has a radial passage therein that conducts compressed fluid from the radial port of the inlet tube to the front chamber, which is configured to form an air spring.

Abstract: A rock drill includes a string of components interconnected by screw threads and connected to a shank. A percussion piston is reciprocated against the shank during a drilling operation, while a support device applies axial support to the rear of the shank, to enhance the drilling action. When the components are being unscrewed, the percussion piston is actuated to strike the rear end of the drill string, after the support device has at least partially released the axial support of the shank, to enable tensile stress to be generated in the components by the percussive impacts to facilitate unscrewing of the components.

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). A tool bit (24) is slidable within the chamber (48) to impact the workpiece (22). Kinetic energy is transferred to the tool bit (24) from the piston (54) via an impact from the piston (54) as the piston (54) slides within the chamber (48). A shock absorbing valve (500) includes a floating collar (502) that is slidable along the casing (42) between two seal rings (504). A handle (34) is mounted to the floating collar (502).

Abstract: An electrically powered hammer comprising a hammer housing (10,15) with a hollow cylindrical spindle (4) mounted within it and an air cushion hammering mechanism mounted within the spindle for generating repeated impacts on a tool or bit of the hammer which hammering mechanism includes a piston (24). A rotatingly driven intermediate shaft (6) is rotatably mounted in the housing and a wobble drive arrangement (12, 16, 18, 20) reciprocatingly drives the piston (24). The wobble drive arrangement includes a wobble sleeve (12) rotatably mounted on the intermediate shaft (6) and a wobble bearing (14, 16, 18) on the wobble sleeve. A support bearing (46, 42) for the intermediate shaft is mounted on the wobble sleeve forwardly of the wobble bearing assembly. The support bearing (46, 42) comprises a bearing ring (46) and the bearing ring is formed with a peripheral flange which can be fixed to a housing part (10) of the hammer housing (10,15).

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 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). A tool bit (24) is slidable within the chamber (48) to impact the workpiece (22). Kinetic energy is transferred to the tool bit (24) from the piston (54) via an impact from the piston (54) as the piston (54) slides within the chamber (48). An energy absorbing mechanism (402) reduces the kinetic energy of the tool bit (24) after impact by the piston (54). The energy absorbing mechanism comprises a sleeve (404) that slides along the casing (42) and first (412) and second (414) pressure chambers that dissipate the kinetic energy of the tool bit (24) in multiple stages.

Abstract: A setting tool for driving fastening elements in a constructional component includes a drive piston displaceable in the guide space (11) of the piston guide (12) by propellant gases generated by a propellant charge from an initial position (40) thereof in the rear region (11.2) of the guide space (11) to an end position (41) in the front region (11.1) of the guide space, and a storage space (20) for the propellant gases and connected by a first valve (23) with the rear region (11.2) of the guide space (11) and connected by a second, electronically controlled valve (24) arranged at an outlet (21) of the storage space (20), with a time-delay, with the front region (11.1) of the guide space (11).

Abstract: A pneumatic linerbolt removing tool including a moil supported for reciprocal movement along a hammer axis within a housing, an inertial body movably mounted along the hammer axis, and a piston assembly moveable within the inertial body along the hammer axis between a striking position at which it strikes the moil and a retracted position remote therefrom. The tool further including a gas-charged accumulator for urging the piston toward the moil and air supply to a cylinder adapted to urge a biasing piston on the inertial body relative to the housing and toward the moil. The inertial body being ported so that working air is supplied to a front face of the piston assembly to urge it to a coked position away from the moil and whereby the accumulator is in its compressed state, and selectively operable porting for equalizing pressure between the front and rear faces of the piston, to continuously allow transfer of air between the faces while in operation.

Abstract: An air hammer includes an air hammering mechanism and a vibration suppressing device to absorb the vibration transmitted from the air hammering mechanism. The vibration suppressing device includes a cylinder forming a front channel and a rear channel in communication with each other. First and second air passageways are defined in the cylinder and in communication with the front and rear channels respectively. A valve is movably received in the front channel. The valve defines a bore and third air passageways selectively alignable with the first air passageways. A piston is movably received in the rear channel and forms a projection. A jacket surrounds the cylinder to form therebetween an air chamber that communicates the second air passageways. The jacket has a closed end defining a hole into which the projection is selectively received to block the hole.

Abstract: A pneumatic percussive tool for a paving breaker and/or a hammer drill, provided with a drive piston which is axially displaceable both backwards and forwards, comprising a guide sleeve and a piston bottom supporting the guide sleeve. A percussion piston can be displaced axially in the guide sleeve of the drive piston with the piston head thereof in percussive mode. During the transition from percussive to idling mode, the piston head slides out of the guide sleeve in such a way that the percussion piston is substantially maintained in the idling mode in an axially displaceable manner by means a stationary part of the percussion tool housing as opposed to being so maintained in the guide sleeve. The axial length of the drive piston can be reduced, whereby the mass of the drive piston and vibrations caused by the movement of the drive piston in the percussive and idling mode can also be reduced.

Abstract: A percussion hammer drill and/or percussion hammer that can be guided by a handgrip comprises a pneumatic spring striking mechanism with a reciprocating drive piston and with a percussion piston that can be operated by the drive piston. A cavity for accommodating a pneumatic spring is provided between the drive piston and the percussion piston. The cavity can be connected to the surrounding area via a no-load operation channel in order to achieve a no-load operation.

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: An apparatus for generating an impact against a target object comprises a driver reciprocally disposed in a housing. The driver includes a hollow tube having a closed end and a nozzle sealing the other end. A piston is slidably positioned in the tube. Propellant is disposed between the piston and the closed end of the tube and fluid is disposed between the nozzle and the piston. A rupture disc is provided for sealing the nozzle which is adapted to rupture when the pressure in the tube exceeds a predetermined pressure. A striker is also mounted in the housing so that in a retracted position of the striker a head portion is proximate the driver and a portion of a shaft extends outwardly from the housing. The striker member is movable between the retracted position and an extended position. The propellant is ignited so that combustion gases build pressure in the tube between the piston and the closed end of the tube causing the pressure in the tube to exceed the predetermined pressure for rupturing the disc.

Abstract: A breaking apparatus, which comprises a percussion device (1), and in the extension thereof, a tool (3) to which a percussion piston (2) belonging to a percussion device delivers impacts. In the axial direction, the movement of the tool is limited by a stopper element (15) if the movement of the tool exceeds a predetermined range of movement (B) in the direction of the impact (A). The stopper element (15) is a piece made of elastic material, which is arranged in a space between the tool and a supporting surface (16). During the stopping of the tool, the capacity of the space for the stopper element reduces, whereby the element is subjected to pressing. By the effect of the tool movement, the stopper element thus rotates about its cross-sectional central axis (21) and at the same time changes its cross-sectional shape in the reducing space. The invention further relates to a tool used in the above-described breaking apparatus.

Abstract: An impacting apparatus and a vehicle having such an apparatus, the apparatus having a mounting portion securable to the vehicle, a tool support portion pivotally connected adjacent a first edge of the tool support portion to the mounting portion via a pivotal connection and flexibly connected at a second edge of the tool support portion to the mounting portion via a flexible connection remote from the pivotal connection, vibration means mounted between the mounting portion and the tool support portion for reciprocating the tool support portion relative the mounting portion via the flexible connection and a tool extending from the tool support portion. The flexible connection comprises resilient elements held by a fastening means between end plates. The fastening means has tightening means for adjusting the flexible connection to a predetermined compression setting of the resilient elements.

Abstract: A pneumatic percussion power tool has a percussion tool housing in which a drive piston and a percussion piston are movable in an axial direction. The motion of the drive piston, which is generated by a crank mechanism, is transmitted to the percussion piston through a pneumatic spring in a first chamber so that the percussion piston cyclically strikes a ram or a tool. The backward motion of the percussion piston rebounding from the ram is supported by increasing air pressure in a third chamber that is supplied with air by the drive piston through a second chamber and a communicating channel.

Abstract: An apparatus for converting measurement signals into digital signals suitable for processing in a microprocessor (12), with the signals having been initiated in a piezo sensor (6) by accelerations acting on the sensor during the impacts of a percussion device (1), particularly a hydraulic hammer, and being used to determine the number of work strokes that have been executed in the impact direction (arrow 3) of the percussion device (1).

Abstract: In a conventional impact generator, a great shock is generated when a weight collides with a rotary member, and a rotary shaft of the rotary member and a bearing supporting the rotary shaft receive the great shock. Therefore, it is necessary to employ a bearing having a great load capacity. Furthermore, great vibrations and noises are also generated in the impact generator. A rotary member (10) is rotatably supported by rotary shafts (11) and (12). A weight (30) is movably held by the rotary member (10). A shock absorber (40) for absorbing, by elastic force, a shock generated between the weight (30) and the rotary member (10) is provided between the weight (30) and the rotary member (10).

Abstract: A percussion mechanism for an electrical hand-held power tool including a guide tube, a percussion piston (4) axially displaceable in the guide tube (2), an anvil (5) for impacting a working tool and axially displaceable together with the percussion piston (4), a gas spring (1) provided on an axial side of the percussion piston (4) remote from the anvil (5), an air channel (9) for aeration of the gas spring (1) and extending between an axial region of the gas spring (1) and an axial region of the anvil (5) outwardly of the inner surface of the guide tube (2), and a ventilation opening (8) for communicating the air channel (9) with a surrounding environment and which is closed by the anvil (5) in its operational position.

Abstract: An electrohydraulic pavement breaker system having cavities (28, 30) which are filled with hydraulic fluid (oil) or gas, and which provide mass spring system which is resonant at a frequency which is especially adapted for breaking and rubblizing concrete pavement. The resonant mass (18) is in impacting relationship with the pavement through a shoe (12), which shoe (12) may be part of an assembly which is pivotally mounted on the support structure (10) of the breaker and is vibrated with the mass (18) to repeatedly impact the pavement at the rate of the resonant frequency. An electrohydraulic control system is responsive to the motion and average position of the mass of the vibrator and controls the driving force so as to be at the resonant frequency of the mass spring system and have the amplitude and energy suitable for breaking the pavement.

Abstract: A breaking apparatus, which comprises a percussion device (1), and in the extension thereof, a tool (3) to which a percussion piston (2) belonging to a percussion device delivers impacts. In the axial direction, the movement of the tool is limited by means of a stopper element (15) if the movement of the tool exceeds a predetermined range of movement (B) in the direction of the impact (A). The stopper element (15) is a piece made of elastic material, which is arranged in a space between the tool and a supporting surface (16). During the stopping of the tool, the capacity of the space for the stopper element reduces, whereby the element is subjected to pressing. By the effect of the tool movement, the stopper element thus rotates about its cross-sectional central axis (21) and at the same time changes its cross-sectional shape in the reducing space. The invention further relates to a tool used in the above-described breaking apparatus.

Abstract: A hand held-type apparatus for fracturing a gate or riser from a casting subsequent to a foundry pouring process. The apparatus operates off of a driven piston assembly, which upon a stroke of such causes a hammer end of the piston assembly to extend from the apparatus and contact the casting, thereby causing the fracturing of the gate or riser from the casting. The apparatus also includes an assembly for decelerating the driven piston assembly upon a stroke of such, as well as an apparatus for isolating the linear motion of the apparatus from the operator thereof.

Abstract: This invention relates generally to an impact tool. The present invention provides a vibration isolated impact tool wherein an impact mechanism and a motor assembly are arranged into a cartridge assembly. An elastomeric member resiliently connects the cartridge assembly with a housing. The cartridge assembly is free to move axially and rotationally within the housing. The elastomeric member absorbs axial vibration and torsional vibration, reducing the vibration transmitted to an operator.

Abstract: A damper pressure control apparatus for a hydraulic rock drill is automatically adjustable of damper pressure to be applied to a damping piston depending upon a thrust of a rock drill body and makes damping function and floating function effective even when thrust of hydraulic rock drill is varied. The damper control apparatus is thus provided damper pressure control means for controlling the damper pressure (DPpr) to be applied to a damping piston (16, 17) from a hydraulic pressure source (21) based on the frontward thrust (F1) acting on the hydraulic rock drill body 1.

Abstract: A percussion power tool assembly (10) comprises a hand-held percussion power tool (11), a chamber (12) mounted on the tool (11), and a fluid reservoir (14) supported independently of the tool (11). The percussion power tool (11) has a body (20) housing a reciprocating hammer (22) which impacts against tool bit (24) in a conventional manner. The hammer (22) is operated by compressed air admitted though valve (26) in feed line (28). The chamber (12) communicates with the fluid reservoir (14) though flexible hose (16). The chamber (12) surrounds the body (20) and has a flexible lining (30) defining a bladder which inflates/deflates in sympathy with fluid filling, or emptying from, the chamber. The deadweight of the hand-held part (18) of the assembly (that is, the tool and chamber combined) is varied by transferring fluid, e.g. water, in the reservoir (14) to the chamber (12), and reduced by returning transferred fluid to the reservoir (14).

Abstract: A damper pressure control apparatus for a hydraulic rock drill is automatically adjustable of damper pressure to be applied to a damping piston depending upon a thrust of a rock drill body and makes damping function and floating function effective even when thrust of hydraulic rock drill is varied. The damper control apparatus is thus provides a damper pressure control for controlling the damper pressure (DPpr) to be applied to a damping piston (16, 17) from a hydraulic pressure source (21) based on the frontward thrust (F1) acting on the hydraulic rock drill body 1.

Abstract: An arrangement in a rock drill comprising a shank and a percussion piston and lifting sleeve for moving the shank towards percussion piston, and a method of controlling rock drilling. The arrangement comprises a lifting sleeve around the shank and a plurality of cylindrical lifting pistons around the shank. In the method, upon downward drilling, the magnitude of the feed force of the rock drill is decreased as the number of extension rods increases, and a force is set to act on some lifting pistons to move the shank towards the percussion point.

Abstract: A rotary impacting apparatus is provided which comprises a housing, a rotor rotatably accommodated in the housing, a driving source for rotating the rotor about a rotation axis, a main reciprocative implement reciprocatively held by the housing, and an impact member eccentrically held by the rotor. The impact member exerts an impacting force for pressing the main reciprocative implement when the main reciprocative implement is advanced relative to the rotation axis. The main reciprocative implement is provided with a diametrically smaller portion and a diametrically greater portion connected to the diametrically smaller portion.

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 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 compressed-air-operated percussion mechanism includes a housing, a percussion body and a balancing body, which form an operating chamber therebetween. A secondary valve seals the operating chamber during an operating stroke and opens the chamber to evacuate compressed air after the termination of the operating stroke. A primary valve is connected to the compressed air inlet passage and intermittently opens to provide compressed air to the operating chamber.

Abstract: A portable pneumatic tool includes a housing composed of two symmetric half shells or several partially cut-away shells; an air inlet module unit, a valve actuating module unit and an operating (or functioning) module unit fluidically communicated with one another and connected with flexible hoses among the module units; and a shock-absorbing unit retained between the operating module unit and the housing; whereby upon embedding or fixation of all the module units into the corresponding cavities in the shells and upon combination of the shells, a portable pneumatic tool will be instantly obtained having advantages of light weight, shock-absorbable property, easy assembly, lower production cost and convenient maintenance.

Abstract: A improved apparatus for decelerating a piston and impacting rod assembly within a single stroke foundry impactor utilizing a non-metallic deceleration piston slidably positioned within a pressurized deceleration chamber mounted proximate the end of the bore containing the impactor piston and impacting rod assembly. The deceleration piston is biased towards the impactor bore by pressurization of the deceleration chamber, such that upon a stroke of the impactor, the residual kinetic energy of the piston and impacting rod assembly is absorbed by the biased deceleration piston.

Abstract: The invention relates to a pyrotechnically operated bolt-setting tool having a barrel (11, 12) which is guided in a barrel-guiding sleeve (1) and can be brought into operative engagement with a locking part (18), the barrel-guiding bore (26) of which accommodates a piston (21), which has a piston shank (23) and a piston head (22), and which has a cartridge store (16) on that side which is remote from the mouth, in which bolt-setting tool the barrel (11, 12), on its side which faces the cartridge store (16), has ventilation slots (31) which are released by the piston head (22) as the bolt is being fired, before the piston (21) reaches its end position on the mouth side, in which position an air cushion is compressed between the piston head (22) and the barrel (11, 12), which air cushion subsequently presses the piston (21) back into its starting position.

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 relates to an arrangement in connection with a hydraulically operated impact device, such as a breaking apparatus. The impact device includes a percussion piston, conduits for feeding pressure fluid into and out of the impact device, and a pressure accumulator. According to the inventive idea, the pressure accumulator is formed as an annular structure surrounding the percussion piston. It consists of sleeve-shaped pressure chambers that are separated by a sleeve-like diaphragm arranged between a frame and a sleeve. The pressure chambers are formed such that the inner circumference of the sleeve placed around the frame and the outer circumference of the frame are provided with recesses opposite one another.

Abstract: The invention relates to a pyrotechnically operated bolt-setting tool having a barrel (11, 12) which is guided in a barrel-guiding sleeve (1) and can be brought into operative engagement with a locking part (18), the barrel-guiding bore (26) of which accommodates a piston (21), which has a piston shank (23) and a piston head (22), and which has a cartridge store (16) on that side which is remote from the mouth, in which tool the rear side of the piston head (22) is connected through the piston (21) to its front side in such a manner that some of the combustion gases are guided to the front side of the piston head (22), and in which the barrel (11, 12), on its side which faces the cartridge store (16), has ventilation slots (31) which are released by the piston head (22) as the bolt is being fired, before the piston (21) reaches its end position on the mouth side, in which position a gas cushion is compressed between the piston head (22) and the barrel (11, 12), which gas cushion subsequently presses the pisto

Abstract: An in-hole hammer for boring in ground has an elongated hollow housing carrying an internal striking piston in a piston chamber. An exchangeable boring head is threadably connected to the forward end of the housing and the striking piston impacts against the forward wall of the housing defining the piston chamber to transmit forward driving impact energy to the boring head. A boring rod which urges the hammer forwardly and rotates it about the longitudinal axis is connected to the rear end of the housing through a connecting piece non-rotatably fixed, but slidable relative, to the housing so that the axially directed impact energy produced by the striking piston is not transmitted to the boring rod.

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 pneumatic impact breaker comprises a housing (11) with a cylinder bore (20), a hammer piston (28) with a piston head (63) and an impact delivering stem portion (64), an anvil (14) displaceably supported in a cylinder bore extension (50) and normally abutting against the shank (15) of a working implement (16), an annular energy absorbing air cushion chamber (59) is formed between the hammer piston (28), the cylinder bore (20) and an annular shoulder (49) in the cylinder bore (20), wherein the piston head (63) is formed with two axially spaced end portions (65, 66) for guiding and sealing cooperation with the cylinder bore (20).

Abstract: A hammer assembly which decreases the severity of impact shocks generated by the hammer assembly during operation thereof is disclosed. The hammer assembly includes a housing defining a chamber. The housing further defines an injector port and an exhaust port each being in fluid communication with the chamber. The hammer assembly further includes a work tool positioned in the chamber, a piston positioned within the chamber, a first hydraulic pressure source which moves the piston in a work stroke toward the work tool, a second hydraulic pressure source which moves the piston in a return stroke away from the work tool, and a damping fluid source in fluid communication with the injector port. The hammer assembly still further includes a first valve which allows damping fluid to be advanced from the damping fluid source and into the chamber during the work stroke, and prevents damping fluid from being advanced from the damping fluid source and into the chamber during the return stroke.

Abstract: An explosive powder charge operated setting tool includes a housing (1), a handle (2) located on the housing, a piston guide (4) and a firing pin guide (8) each located within and being axially displaceable relative to the housing against the force of a damping device (17) bearing against a trailing end stop face within the housing directed in the driving direction. The housing (1) forms an axially extended receiving space (24) for guiding the piston guide (4). The receiving space has an axial length (LA) between a leading end face of the housing and a leading end face of the firing pin guide in a first position. The piston guide (4) has an axial length (LK) coinciding at the most with the axial length (LA) of the receiving space.

Abstract: A hydraulically operated rock drill including a cylinder, a piston mounted for reciprocating movement in the cylinder, a hydraulic fluid line connected to the cylinder, and an accumulator. A chamber with a section of reduced dimensions is formed in the cylinder, and the piston includes an annular formation which moves within the chamber and into and out of the section as the piston reciprocates. The accumulator is connected via a port to the section, and the hydraulic fluid line is connected to the chamber and is in communication with the accumulator when the annular formation is out of the section and which is cut off from the accumulator, by the annular formation, when the annular formation moves into the section, the annular formation then pressurizing hydraulic fluid in the section whereby hydraulic energy, produced by kinetic energy developed over at least part of a return stroke of the piston, is stored in the accumulator. A second accumulator is connected at least to the high pressure line.

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: An apparatus for generating impacts which has a hydraulic cylinder and a reciprocating piston. The hydraulic cylinder has an impact chamber, a cavity which receives and diverts fluid, and a throat which connects the impact chamber with the cavity. When the pressure line is connected to the cavity, the piston is lifted to an upper position. When the overflow line is connected to the cavity, the piston drops down such that the piston enters and covers the throat at the impact chamber. The pressure in the chamber remains low as the chamber is sealed by the piston entering the throat, where the energy loss is insignificant. The piston enters into the throat such that it is stopped and presses against the fluid inside the impact chamber, and thereby generates an impact therein. The piston is lifted up to repeat the cycle, when the cavity is connected to the pressure line.

Abstract: A double-acting hydraulic striking tool, wherein a hammer's (8) upper end (9) is rigidly connected to an upper piston (10), and wherein the hammer's (8) lower end (26) is rigidly connected to a lower piston (26). The pistons (10, 27), which can be displaced within a tubular housing (11), are adapted to open and close for a forced flow of liquid from the upper end (9) of the hammer (8) towards the lower end (26). The hammer (8) is activated for downwardly directed blows by pressing against the hammer's (8) upper end (9) with a resilient force, causing the lower piston (27) to close the liquid flow, whereby the housing (11) is lifted hydraulically until the piston (27) opens for the liquid flow, and the forced spring force drives the housing (11) downwardly to impinge on the hammer's (8) lower end (26) through impact faces (34, 36).

Abstract: A water driven hammer device has a machine housing and a hammer piston movable to-and-fro in the machine housing. The hammer piston is guided in the machine housing in two guides separated from each other. The guides are formed from two parts each having different inner diameters, and the parts with the largest inner diameters on the guide are turned towards each other. A room between the guides is pressurized and chambers on the other side of the guides are kept at a lower pressure, resulting in fluid flow through the guides for centering the hammer piston in the machine housing to avoid seizure of the hammer piston.

Abstract: An airflow regulation arrangement for regulating the impact of the strikes delivered from a striking member (6) to an intermediate member (10) and a bit, thus reducing the vibration, and also for regulating the impact of recoils of the striking member (6) is disclosed for use in an electrical hammer (1). The airflow regulation arrangement comprises an air inlet (14) provided in an air chamber (5) in a cylinder (3) of the electrical hammer (1), exhaust ports (15) provided in a second air chamber (9), and air passages (16) in communication with the air inlet (14) and the exhaust ports (15). The air passages (16) are connected to choke passages (17), the cross sectional area of which is one fifth to one sixth of that of the air passages (16).