Abstract: A hydraulic hammering device enables an auto-stroke mode and an idle strike prevention mode to coexist with a simple circuit configuration. A first control valve controls advancing and retracting movements of a piston and a second control valve select either the auto-stroke mode and the idle strike prevention mode. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mode is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mode is selected.

Abstract: A driving cylinder of a pile driving rig includes a solenoid valve for controlling an operation of the driving cylinder, which solenoid valve, is a slide valve, which is located at least partly at a piston-side head of the driving cylinder, and a stem of the slide valve is at least partly outside an inner cylinder liner in a direction of motion of a piston part. Further disclosed is a pile driving rig comprising the driving cylinder according to the invention.

Abstract: Hammering power of a hydraulic hammering device is improved by shortening a piston stroke, while keeping hammering energy. The device includes a cylinder, a piston slidingly fitted in the cylinder, and a piston front chamber and a piston rear chamber defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and disposed separately from each other at front and rear, respectively, in an axial direction. The device also includes a switching-valve mechanism driving the piston by switching at least one of the piston front or rear chamber into communication with at least one of a high pressure circuit or a low pressure circuit, and an acceleration piston disposed behind the piston and coming in contact with the piston during a retreat stroke of the piston to urge the piston forward in cooperation with braking force by pressurized oil acting on the piston.

Abstract: The invention concerns a rock breaking device comprising a striking cell having at least one actuation chamber, a striking piston, and a hydraulic circuit comprising a hydraulic supply source having a High Pressure circuit and a Low Pressure circuit, and an actuator configured to connect the High Pressure circuit or the Low Pressure circuit to the actuation chamber so as to move the piston in translation in the striking cell in a normal movement area of which the limits are variable depending on the pressure difference between the High Pressure circuit and the Low Pressure circuit, the striking cell comprising depressurizing means configured to control the establishment of hydraulic communication between the High Pressure circuit and the Low Pressure circuit when the striking piston exits a predefined movement area.

Abstract: The present invention relates to a method of power management during pile foundation having a base machine for excavating a borehole and an attachment installed at the base machine for a simultaneous introduction of a casing into the ground, wherein the energy supply for the attachment is at least partially provided by the base machine and a control of the base machine dynamically regulates the energy flow from the base machine to the attachment.

Abstract: This percussion apparatus includes a striking piston, a control distributor arranged to control a reciprocating movement of the striking piston, and a control device arranged to vary the striking stroke of the striking piston. The control device comprises a plurality of control channels, a control channel connected to the control distributor, a control slide movably mounted between a plurality of control positions, and an adjusting slide mounted in a receiving housing delimited by the control slide, the control slide and the adjusting slide delimiting a first adjusting chamber connected to the control channel and a second adjusting chamber connected to a the high-pressure fluid supply circuit. The control slide is movably mounted between a first position in which the first control chamber and the second adjusting chamber are connected and a second position in which the first control chamber and the second adjusting chamber are isolated.

Abstract: An accumulator assembly includes a vessel having an upper portion and a lower portion. The accumulator assembly includes a flexible membrane extending between the upper portion and the lower portion. The membrane may divide the vessel into a first interior chamber and a second interior chamber. The accumulator assembly includes a receptacle located proximate the vessel. The receptacle may be in fluid communication with the second interior chamber. The accumulator assembly includes a plunger located at least partially within the receptacle.

Abstract: A switching method includes starting up a percussion device in acting on a control device arranged to vary the striking stroke of the striking piston between a short striking stroke and a long striking stroke. The percussion device is forced to operate on a short striking stroke for a predetermined period of time from the starting up of the device, and in acting on the control device so as to allow the percussion device to operate on a long striking stroke, after the expiry of the predetermined period of time.

Abstract: A hydraulic impact mechanism, of the valveless impact mechanism type, comprising a pre-charged gas accumulator connected to a working chamber in order to make possible impact mechanisms for equipment for rock drilling and hydraulic breakers that is lighter, cheaper and more sustainable from the point of view of material fatigue. Furthermore, a gas accumulator of piston type with an integral brake chamber (240, 250, 360) and a piston (220, 320) designed to fit into the said brake chamber (240, 250, 360).

Abstract: A system is provided for communicating within a borehole using controlled vibrations. A movement mechanism uses mechanical energy provided by a mechanical energy source to enable translational movement of a first surface relative to a second surface to allow the first surface to repeatedly impact the second surface to produce a plurality of vibration beats. The vibration beats will occur whenever the mechanical energy is provided by the mechanical energy source at one of at least three impact levels. A vibration control mechanism selectively controls an amplitude of the plurality of vibration beats to encode information therein. The amplitude of a vibration beat is selectively controlled by regulating the impact of the first surface and the second surface to one of the at least three impact levels.

Abstract: An impact system for a hydraulic hammer is disclosed. The impact system may include a piston, a sleeve disposed co-axial with the piston, and an accumulator membrane disposed external to the sleeve. A first seal may be located at an end of the sleeve, and configured to connect the sleeve to the piston. The accumulator membrane may have an extension configured to engage a recess in the sleeve.

Abstract: A system and method are provided for producing controlled vibrations within a borehole. In one example, the system includes a movement mechanism and a vibration control mechanism. The movement mechanism is configured to use mechanical energy provided by a mechanical energy source to enable translational movement of a first surface relative to a second surface to allow the first surface to repeatedly impact the second surface to produce a plurality of vibration beats, where the vibration beats will occur whenever the mechanical energy is provided by the mechanical energy source unless the provided mechanical energy is dampened to prevent the translational movement. The vibration control mechanism is configured to selectively control an amplitude of the vibration beats to encode information therein, where the amplitude of a vibration beat is selectively controlled by dampening the provided mechanical energy to regulate the impact of the first surface and the second surface.

Abstract: The invention relates to a system for installing or removing foundation elements, such as piles, anchors, and conductors, in a subsea ground formation, comprising an impact weight, an hydraulic circuit in turn comprising an hydraulic cylinder for lifting and/or accelerating the impact weight respectively away from and towards the element, the cylinder comprising a piston connected to the impact weight, and wherein a pump for generating an underpressure in the hydraulic cylinder such as to lift and/or accelerate the impact weight by means of this underpressure.

Abstract: A method for controlling a fluid operated percussive device, which inside an axially extending cylinder room (3) of a housing (2) of the percussive device includes a to and fro moveable percussive piston (1), which is adapted for performing strikes in a striking direction (A) and which includes a signal portion (4) for controlling a main valve (5), which is adapted to intermittently transmit pressure fluid to at least one driving chamber (7) for the percussive piston. An auxiliary valve (9) is controlled for transmitting fluid contact between at least one auxiliary channel means (13,14) with a channel opening in the cylinder room (3), and the main valve (5) over the signal portion (4), for switching the main valve (5) before the percussive piston, in operation, has reached at least one of said regions. The invention also concerns a percussive device and a rock drilling machine.

Abstract: A hydraulic hammer includes a powercell housing that defines a hydraulic inlet and a hydraulic outlet. A machine mount that defines a plurality of pin receiving bores is attached to the powercell housing. A work tool is partially received in, and movable with respect to, the powercell housing. A switching spool valve member is positioned in the powercell housing and is movable between a first position and a second position, and includes a control hydraulic surface. A sleeve/liner assembly is positioned in the powercell housing and defines a centerline. A piston with a plurality of hydraulic surfaces is positioned in the sleeve/liner assembly and is movable along the centerline between a first position in contact with the work tool and a second position out of contact with the work tool. The control hydraulic surface of the switching spool valve member is exposed to fluid pressure in a switching passage, which includes a segment defined by the sleeve/liner assembly.

Abstract: According to the invention, the body of the apparatus includes a flow rate adjustment device including a calibrated opening provided on a high-pressure fluid supply circuit, a bore formed in the body and in which is mounted a slider having a first face located in a first chamber connected to a high-pressure fluid supply circuit upstream from the calibrated opening and a second face located in a second chamber connected to the high-pressure fluid supply circuit downstream from the calibrated opening, the bore receiving the slide including an annular groove connected to a low pressure feedback circuit. The slider is adapted for connecting the annular groove to the first chamber when the pressure difference on either side of the calibrated opening increases beyond a predetermined value in order to divert a portion of the fluid flow supplied by the high-pressure fluid supply circuit to the feedback circuit.

Abstract: A pressure fluid operated impact device comprising a frame (2) whereto a tool (3) is mountable movably in its longitudinal direction, and control means (7) for controlling pressure fluid feed to the impact device (1), as well as a method of generating a stress pulse in a pressure fluid operated impact device. The impact device (1) comprises a working chamber (8) and a transmission piston (9) moving therein. Energy charging means for charging energy of pressure fluid and the control means are coupled to allow periodically alternately pressure fluid to flow to the working chamber (8) and, correspondingly, to discharge pressure fluid from the working chamber (8). In the method, pressure fluid is fed to the working chamber (8), which produces a force pushing the transmission piston (9) in the direction of the tool (3), thus generating a stress pulse in the tool (3).

Abstract: The present invention relates to a control device for an impulse-generating device for inducing a shock wave in a tool, in which said impulse-generating device comprises an impact element for transmitting said shock wave to said tool, a counter pressure chamber acting against the impact element and a device for reducing a pressure in the counter-pressure chamber. The control device comprises control means for regulating the reduction of the pressure in said computer-pressure chamber. The invention also relates to an impulse-generating device.

Abstract: A percussive assisted rotary drill includes a top sub for connection with a drill pipe. The drill pipe imparts torque to the drill and also supplies motive fluid to the drill. The drill includes a shank adapter to facilitate affixing a rotary drill bit to the drill. The motive fluid is divided between a bit flow which flows through the bit to clear debris at the bottom of the drill, and an actuator flow. An actuator, which may be in the form of a reciprocating piston, moves within the drill under the influence of the actuator flow to impart cyclical blows to the shank adapter. At least a portion of the actuator flow portion of the motive fluid is exhausted through the top end of the drill.

Abstract: Pneumatic drifters containing a drifter cylinder with removable feet and associated methods for using the pneumatic drifters are described. The removable feet are connected to feet pad of a drifter cylinder with multiple fasteners. The mating surfaces of the feet and the feet pad are provided with complimentary features that limit the shearing forces on the fasteners during operation of the drifter rock drill. The removable feet can be replaced quickly and easily without have to replace the entire drifter cylinder, thereby saving time and reducing costs. Other embodiments are also described.

Abstract: A device for driving various objects using combustible fuel. Embodiments are contemplated in which the driver could be a post-driver, a power shovel, a jack-hammer or other devices. Typically, the device includes a body with a combustion chamber. A fuel injection valve selectively supplies fuel to the combustion chamber where it can be ignited using an ignition module. A piston is movable within the body to impact the ram responsive to combustion in the combustion chamber.

Abstract: The invention relates to an impulse generator (2) for a rock breaking tool, which comprises a propulsion chamber (6) for receiving a pressurizeable liquid volume (8), and an in the propulsion chamber (6) received impulse piston (10), where the impulse piston (10) is arranged for transfer of pressure peaks in the liquid volume (8) into impulses in the tool (12), whereby transfer of energy from a propulsion mechanism (14) into impulses in the tool (12) is effected by volume reduction of the propulsion chamber (6), whereby the impulse piston (10) is driven forward by a pressure peak in the propulsion chamber (6). The invention also relates to a hydraulic impulse tool comprising an impulse generator (2).

Abstract: An improved impact power tool for carving and engraving an article comprises an air delivery system operable to communicate with a pressurized air source; a drive assembly operable to receive air from the pressurized air source via the air delivery system; a hand held device in driven communication with the drive assembly; and a housing for storage of the air delivery system and drive assembly. The tool includes an improved valve design, a throttle bias valve, and an air storage tank housed within the housing, and an improved housing construction. The improved valve design and air storage tank enable greater stroke speeds of a work tool over a wider power range while also improving the crispness and speed of the impact reaction time over the entire range. The throttle bias valve is in communication with an additional exhaust path, such that the bias valve allows improved control of the hand held device and improved operation over a wider range of air pressures.

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 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 percussive device including, inside a machine housing (3), a reciprocally moveable percussive piston (2), the movement of which being controllable through a control valve (5), which is arranged to alternatively connect a chamber to a pressure source and to low pressure in dependence of a signal describing the axial position of the percussive piston, wherein valve means (16) are arranged to allow adjustment of in which axial position of the percussive piston said signal is transmitted, through respectively opening and blocking of connection between one or a plural of said control channels (10,11,12,13) and the control valve. The invention also concerns a rock drilling machine and a method.

Abstract: Pneumatic drifters containing a drifter cylinder with removable feet and associated methods for using the pneumatic drifters are described. The removable feet are connected to feet pad of a drifter cylinder with multiple fasteners. The mating surfaces of the feet and the feet pad are provided with complimentary features that limit the shearing forces on the fasteners during operation of the drifter rock drill. The removable feet can be replaced quickly and easily without have to replace the entire drifter cylinder, thereby saving time and reducing costs. Other embodiments are also described.

Abstract: The equipment comprises a body (2) inside which there are a bore in which a tool (3) is slideably mounted and a stepped bore forming a cylinder for a stepped piston (1) which together with this bore delimits a top chamber (5) and a bottom chamber (4) which chambers are sequentially supplied with incompressible fluid under high pressure under the action of a directional control valve (6), a control device varying the stroke of the striking piston between a long stroke and a short stroke and vice versa. The control device comprises a cylinder into which there opens at least one port (14) which also opens into the cylinder of the striking piston (1), and a port (13) connected to the directional control valve and in which a spool (12) is mounted, a first face of which spool lies in a first chamber (17) constantly subjected to a determined pressure and the second face of which spool lies in a second chamber (21) connected to a braking chamber (10).

Abstract: Percussion device including a machine housing (1), a forwards and backwards movable percussion piston (2) in the machine housing, and a reciprocatingly movable tubular valve body (6) inside the machine housing, said percussion piston (2) being arranged to subject a tool (3) to impact, and said percussion piston including a first (4) and a second (5) driving surface arranged to be pressurized in order to drive the percussion piston forwards and backwards, said valve body (6) including a first end surface (12) and a second end surface (13), wherein pressurizing the first end surface (12) tends to drive the valve body in a first direction and pressurizing the second end surface (13) tends to drive the valve body in a second direction, whereby the valve body (6) is arranged, over a channel (7) arranged in the machine housing, to connect at least the second (5) of the driving surfaces alternately to a pressure source (8) or to low pressure (9), wherein an inner room (31) in the tubular valve body (6) is continuous

Abstract: An improved impact power tool for carving and engraving an article comprises an air delivery system operable to communicate with a pressurized air source; a drive assembly operable to receive air from the pressurized air source via the air delivery system; a hand held device in driven communication with the drive assembly; and a housing for storage of the air delivery system and drive assembly. The tool includes an improved valve design, a throttle bias valve, and an air storage tank housed within the housing, and an improved housing construction. The improved valve design and air storage tank enable greater stroke speeds of a work tool over a wider power range while also improving the crispness and speed of the impact reaction time over the entire range. The throttle bias valve is in communication with an additional exhaust path, such that the bias valve allows improved control of the hand held device and improved operation over a wider range of air pressures.

Abstract: A hydraulic hammer comprising a housing (10) with a longitudinal bore (12), cylinder sleeve (14) supported in the bore (12) a rear and cover (16) closing the bore (12), and a hammer piston (15) reciprocally powered in the cylinder sleeve (14) for delivering blows to a working implement inserted in the guide sleeve (20) mounted at the front end of the bore (12). The hydraulic hammer also comprises a distribution valve (31), for directing pressure fluid to the hammer piston (15), communicating the pressure fluid source and the cylinder sleeve (14). The valve (31) comprises both a clearance seal means (44) and a seat seal (45, 46) for improved tightness.

Abstract: The invention relates to a percussion device comprising two percussion pistons alternately making a percussion motion and a control valve for controlling the percussion pistons. The control valve (7) comprises a slide (8) affected by a force so that the slide is generally in a first position, but moves at the end of the percussion motion of the first percussion piston from the first position to a second position and correspondingly back to the first position at the end of the percussion motion of the second percussion piston (4).

Abstract: A hand-held power tool for use in hand working operations including a hand pressure sensing element for adjusting the power of the tool. More specifically, the invention provides a hand engraving power tool that is activated from absence of power to much greater power or anywhere in between determined by the amount of pressure exerted by a human hand on the tool's handle.

Abstract: Depending on the working and application conditions, it may be desirable to equip fluid-operated percussion devices with a mechanism that protects against no-load strokes, particularly in the interest of avoiding undesired stress. In the present case, this protection mechanism is configured such that the control unit that influences the movements of the percussion piston is blocked by a safety element in the form of a multiple-position valve, and the percussion device is halted if the percussion piston overshoots the extended position occurring in normal operation by a defined distance, thereby assuming a no-load-stroke position. The safety element (21) that acts on the control unit (5) of the percussion device (1) is automatically controlled, notably such that it is not switched to be active until some time after the startup of the percussion device (1) acted on by the working pressure. The percussion device (1) can therefore start up without being influenced by the safety element (21).

Abstract: A manual machine tool (10) includes a vacuum device for dust removal (19) situated in its housing (12) and a blow-out connection (20) installed after this. A dust collection box (21), particulaily self-contained, can be attached in detachable fashion to the blow-out connection (20) via its blow-in connection (22). The dust collection box (21) is airtight on all but two sides and has air-exit holes (40) on the top side (36) and a dustproof filter element (48)—especially a fluted filter—on the inside. The dust collection box is particularly secure against the unintentional escape of dust after the dust collection box is detached from the associated manual machine tool because a pair of sealing lips (500) arranged as a separate part is provided inside the blow-in connection (22), which pair of sealing lips (500) is connected as a single part with closing flaps (520, 520) projecting into the interior of the dust collection box (210).

Abstract: The subject invention pertains to an improved air-operated hammer which can utilize a pressurized air reservoir located near a pressurized air entrance of the hammer. This pressurized air reservoir can continue to receive pressurized air even when the hammerhead is failing and, preferably, can enable pressurized, air to enter the hammer at, a faster rate than the hammer's external compressed-air source can supply. The subject invention can utilize a compressed-air source with a lower flow rate and/or lower pressure in comparison with a typical air-operated hammer, in order to achieve the same hammer performance. Alternatively, the subject invention can utilize an equivalent compressed-air source in comparison with a typical air-operated hammer, in order to achieve superior hammer performance, for example shorter time periods to raise the hammer head leading to move hammer drops per time.

Abstract: An apparatus for a hand-held pneumatic impact tool for use in fine hand working operations includes a handpiece, a foot-operated flow control valve with exhaust and two hand operated flow control valves. The handpiece includes a housing having a cavity and annular shoulder accommodating a stepped piston dividing the cavity into three chambers. The control apparatus provides control for a hand-held pneumatic impact tool that will return an impacting handpiece to a fine oscillation idling state quickly when the user releases the foot-operated flow control valve. The apparatus also provides ease of control for adjusting the idling ready state of the handpiece to a faint oscillation idle.

Abstract: A control system for a heavy duty hydraulic hammer reduces blank firing of the hammer. The control system provides a reduced flow of hydraulic fluid to the hammer for a selected period of time upon actuation of the hammer and then provides full hydraulic flow increasing the frequency of impacts to full rated values.

Abstract: A hand-held pneumatic impact tool for use in fine hand working operations includes a mechanism for adjusting impacting characteristics of the device that is conveniently located and adjusted by the user. The mechanism includes an annular band protruding around the outside diameter of the body of the impact tool that may be turned for adjusting an annular ring in the bore of the tool and thus altering the distance required for the piston to reach impact collision with the anvil. The impact tool also includes a handle containing a receiving-recess and a handle-attachment unit to permit manual removal and installation of the handle. The handle-attachment unit includes more than one protruding member positioned a distance into the receiving-recess, more than one groove on the outside diameter of body and running a distance and in a direction substantially parallel with the central longitudinal axis of the body and then changes direction and rotates around the central longitudinal axis of the body a distance.

Abstract: A fastener installation tool to install fasteners, such as rivets, risers, standoffs, and other types of fasteners operates upon vacuum and air pressure. Fasteners are installed with minimal reactive forces to the operator's hand, thus reducing the risk of repetitive injuries to the operator's body. Vacuum retains the fastener within the tool tip and retracts a piston, until an operator simultaneously presses the fastener against a work piece and actuates an actuation element on the tool. This causes air pressure to quickly thrust the piston against a hammer pin to drive in the fastener, transferring kinetic energy from the piston to the fastener without appreciable kick-back to the operator. A control system provides a source of vacuum and air pressure to the tool. Methods of using a fastener installation tool are also described.

Abstract: A fluid-operated percussion device (1) having a percussive piston (3), which alternately executes a work stroke and a return stroke due to the effect of a control. To avoid no-load strikes, in one embodiment of the percussion device (1), the percussive piston (3) is shut down if it has overshot the extended position occurring in normal operation (long- and/or short-stroke operation) by a predetermined distance in the work-stroke direction (arrow 3e) and reached a no-load-strike position. For this purpose, the interior (2d) of the work cylinder (2) that receives the percussive piston (3) additionally has a no load-strike opening (20a), which is connected to the pressure line (8) of the percussion device (1) with an interposed safety element (21) that can be switched between an inoperative position and an operative position.

Abstract: A fluid-operated percussion device (1) having a percussive piston (3), which alternately executes a work stroke and a return stroke due to the effect of a control. To avoid no-load strikes, in one embodiment of the percussion device (1), the percussive piston (3) is shut down if it has overshot the extended position occurring in normal operation (long- and/or short-stroke operation) by a predetermined distance in the work-stroke direction (arrow 3e) and reached a no-load-strike position. For this purpose, the interior (2d) of the work cylinder (2) that receives the percussive piston (3) additionally has a no-load-strike opening (20a), which is connected to the pressure line (8) of the percussion device (1) with an interposed safety element (21) that can be switched between an inoperative position and an operative position.

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: The invention relates to a hydraulically operated impact device, such as a percussion hammer or some other breaking apparatus, comprising a control valve (6) for controlling pressure fluid supplied to and from the percussion piston (1) so that the direction of motion of the piston (1) can be changed in accordance with the cycle of operation of the impact device. According to the inventive idea, when the control valve (6) is in the impact position, the impact device is provided with a closed space that is partly bordered by the control valve and the percussion piston. The percussion piston (1) comprises a section which communicates with said space and which has a larger diameter than the upper end of the piston. The control valve and the percussion piston are thus able to move in the same direction until a connection is opened from this closed space to the upper end of the percussion piston (1).

Abstract: A percussion piston for use in a drilling apparatus includes a drill bit and at least three tubular parts which increase in diameter in a direction extending from the drill bit toward a rear end of the piston. The piston further includes flanges positioned between the tubular parts and a first corresponding delivery space at the rear end of the piston. At least two additional corresponding delivery spaces are positioned between the first corresponding delivery space and the drill bit. Channels allow the transport of pressurized hydraulic fluid to and from the first and additional corresponding delivery spaces such that an energy pulse produced by impact of the piston on the drill bit is almost completely absorbed by the drilled object.

Abstract: A vibration generating apparatus comprises a cylinder assembly (6) having a cylinder and a piston (3) slidably inserted in a cylindrical bore (2) of the cylinder for defining a first pressure receiving chamber (4) with a small pressure receiving area and a second pressure receiving chamber (5) with a large pressure receiving area. The piston (5) is selectively movable in one direction and in the other direction responsive to pressures in the pressure receiving chambers. A switching valve (9) has a first pressure chamber (13) with a large diameter, a second pressure chamber (14) with a small diameter, a pump port (10), an auxiliary port (23), a principal port (11) and a tank port (12). The switching valve (9) takes a first position under a pressure within the first pressure chamber and takes a second position under a pressure within the second pressure chamber.

Abstract: A fluid-operated striker assembly includes a working cylinder and a striker piston slidably received in the working cylinder for executing working (forward) and return strokes. The striker piston delivers a blow to a tool bit during the working stroke when the striker piston is either in a limit position or in an advanced position which is beyond the limit position in the direction of the working stroke. A control arrangement applies an alternating fluid pressure to the striker piston to execute the working and return strokes. Further, a precontrol arrangement is provided for affecting the control arrangement dependent on whether the striker piston has exceeded its limit position.

Abstract: The impact hammer comprises a working piston (22) exerting impacts onto an impact surface (23). The hydraulically driven working piston (22) is reciprocatingly controlled by a control means (40,41). At the rearward end of the working cylinder (21), there is a rear chamber (50) into which the projection of the piston (51) immerses. Connected to the rear chamber (50) is a pressure gas reservoir (52) which is charged with each return stroke of the working piston and discharges with the subsequent working stroke.

Abstract: The invention relates to a hydraulic percussion hammer comprising a piston (1), a pressure accumulator (7) in the high pressure circuit, a main valve (8) alternately conducing a high and low pressure to at least one of the pressure surfaces (2,4) of the piston (1) for making the piston (1) move reciprocally, and a tool (3) which the piston (1) strikes, and, for the purpose of controlling the main valve (8), a control pressure valve (9) which opens when the pressure exceeds a set value. According to the invention, the control pressure valve (9) is placed in such a way that the spindle (27) of the control pressure valve (9) is connected from one end to the high pressure circuit of the hydraulic percussion hammer.

Abstract: A device for removing runners from intermediate molded products includes a holding assembly for maintaining the products in a desired position, a hammer member, an assembly for vibrating the hammer member to cause repeated striking of the intermediate product so as to separate runner and product portions thereof and a control arrangement for selectively activating and deactivating the vibrating assembly. The control arrangement provides for positioning the vibrating assembly in at least one predetermined position upon deactivation thereof so as to enable the vibrating assembly to be readily restarted. The holding assembly can incorporate a robot arm for transporting and positioning the intermediate molded product for runner removal. In order to protect the robot arm from the effects of vibrational forces, the intermediate molded product is adapted to be resiliently attached to the robot arm.