Abstract: Down-the-hole drilling machine comprising a housing in form of a tube (1), a hammer piston (6) being movable to-and-fro in the tube and intended for impacting a drill bit (5). The hammer piston is at its ends provided with end sections in form of polygons with rounded corners (51, 52). These end sections are turned relative to each other an angle which is half as large as the angle between two adjacent corners.

Abstract: A self-propelled, pneumopercussive, cyclic action, ground penetrating machine (200) has decreased energy consumption and increased average working velocity compared to conventional machines. This is obtained in part by a valve-operated air-distribution mechanism (203) having separate forward and reverse compressed air supply lines (35, 37), which mechanism (203) does not limit the length of the forward and backward strokes of the striker (202). This mechanism allows the backward stroke chamber (75) to be connected with the atmosphere during the entire forward stroke of the striker (202). This eliminates generation of an air buffer in the backward stroke chamber (75) and, consequently, the striker (202) does not lose part of its kinetic energy before impact.

Abstract: Tool for driving fastening elements into a hard receiving material, such as concrete, masonry, rock and the like, has a first device (1) for drilling a fastening element into the hard material and a second device (2) for axially propelling the fastening element into the receiving material after it has been partly drilled in. The first device (1) provides a borehole in the hard receiving material by applying rotary movement to the fastening element, possibly with the addition of axially directed striking force. The second device (2) completes the insertion of the fastening element into the receiving material by directing an axial force produced by high pressure gases against the partly drilled in fastening element.

Abstract: In a ram boring machine that has a striking piston reciprocating in a tubular housing and a striking tip that may be formed as a chisel and projects from the housing, connection of the striking tip to the housing by means of a bayonet joint makes installation and removal or replacement of the striking piston or a worn chisel possible in a simple manner.

Abstract: In a ram boring machine that has a striking piston displaceable in a tubular housing, a displaceably mounted chisel passing through a housing tip has a collar by which it is guided in a bore in the housing that has a front and a rear stop limiting the stroke of the chisel, and has a shank that projects into the working chamber of the striking piston, rebounding blows are avoided by making the length of projection of the shank is smaller than the maximum stroke of the collar between the stops.

Abstract: A drill head is disclosed, for use to drill a hole in a front of hard material such as rock, which comprises a main body acting at a central support, an upwardly projecting spindle secured on top of the main body, the spindle having a vertical axis, a fixation head on top of the spindle for detachably connecting it to a drill shaft operable in use to rotate the drill head about the vertical axis of the spindle and to pull it up toward the front hard material to be drilled, and at least two impact hammers mounted onto the main body in such a manner as to fragment, in use the hard material of the front along at least one circular path centered onto the vertical axis, each impact hammer having a hollow casing, a pneumatically-operated, impact generating assembly enclosed within the casing, and a drill bit actuated by the impact-generating assembly.

Abstract: A compression-vacuum action percussive machine is proposed, which has a casing (1) accommodating a tool (7) and a cylinder (2) with a drive piston (3) and a striker (4) having a chamfer (10) on the end face engageable with the tool (7), and also a means for trapping the striker (4), which means is made in the form of a sleeve (11) with an annular groove (13), wherein a resilient ring (14) is mounted. The sleeve (11) has an inner annular rib (15), the diameter of which is smaller than the diameter of the inner wall (12) of the sleeve (11), the annular rib (15) being positioned at the end face of the sleeve (11) facing the striker (4). The inner diameter (d) of the resilient ring (14) is smaller than the diameter (D) of the extension (9) of the striker (4), which extension is situated after the striker chamfer (10).

Abstract: A self-propelled, pneumopercussive, cyclic action, ground penetrating machine (200) has decreased energy consumption and increased average working velocity compared to conventional machines. This is obtained in part by a valve-operated air-distribution mechanism (203) having separated forward and reverse compressed air supply lines (35, 37), which mechanism (203) does not limit the length of the forward and backward strokes of the striker (202). This mechanism allows the backward stroke chamber (75) to be connected with the atmosphere during the entire forward stroke of the striker (202). This eliminates generation of an air buffer in the backward stroke chamber (75) and, consequently, the striker (202) does not lose part of its kinetic energy before impact.

Abstract: A pressure-medium driven ram boring machine for boring in the earth, having an impact tip acted on by a percussion piston reciprocating in the machine housing, wherein the impact tip is arranged to be radially adjustable in the housing whereby controlled directional changes of the machine can be effected.

Abstract: A cracking device for use in a dredger includes a housing body having an elongated cavity receiving an elongated piston and a hammer rod to be struck by the piston. The cavity forms a gas chamber around a top end of the piston for receiving an operating gas, an annular hydraulic chamber around the piston adjacent to the annular flange, and an impact chamber around a bottom end of the piston and around a top end of the hammer rod. The hydraulic chamber is divided into two variable volume upper and lower chambers by an annular flange of the piston. A passage is provided in the body to permit a hydraulic fluid to operate in the hydraulic chamber through the passage. A hydraulically operated control valve is connected to the passage and the hydraulic chamber for controlling the operation of the hydraulic fluid.

Abstract: An improved ripper using a hydraulic hammer with a rotating long service life hammer tool is provided. The tool is cylindrical with a large cylindrical upper portion and a central portion of reduced diameter. The tool is retained in the hammer by means of a pin passing through the tool cavity of the hammer housing which prevents passage of the large upper portion.

Abstract: A ram boring implement having a pneumatically or hydraulically driven percussion piston, movable axially in a reciprocating manner in a housing, and an axially movable bit which is connected to an end of the housing and acted upon directly or indirectly by the percussion piston, is of a structure which permits a restoring piston, connected to the bit, to be acted upon by the pneumatic or hydraulic pressure during the return stroke of the percussion piston.

Abstract: A percussive action machine for changing the shape of solids objects comprises a housing (1) accommodating a hammer (2) capable of reciprocations. A tail piece (3) of the hammer (2) is disposed inside a power cylinder (6) to impart energy thereto during the work stroke of the hammer, the tail piece being capable of engagement with a drive for executing the return stroke of the hammer (2). The machine is also provided with a unit for decelerating the forward travel of the hammer (2) in the form of an annular projection (20) in the midportion of the hammer (2), and a cavity (17) which accommodates this projection (20), and has a hammer deceleration chamber (21) of a cross-section substantially equal to the cross-section of the projection (20). The side surface of either the hammer decleration chamber (21) or the annular projection (20) is tapered.

Abstract: A diesel type pile-driver has a cup-shaped monkey (36) accommodated in a sliding fit on the external face of the lower end of the cylinder.

Abstract: A tubular sleeve clamps the work during a drilling step, following which a tubular anvil moves within the sleeve to support the work while a rivet is thrust into the work with an interference fit. The tubular anvil is then withdrawn and moved with an anvil pin to form an upset head. If desired, the pin can then be retracted, and the outer portion of the upset head partially sheared by the tubular anvil and flattened against the work.

Abstract: A hammer drill has clamping jaws which are provided, in addition to clamping surfaces for radial clamping a cylindrical tool shaft, also with additional axially extending guiding surfaces for axially non-rotatably holding and guiding of the tool shaft, and the tool shaft is provided with guiding grooves associated with the clamping jaws.

Abstract: A percussion tool utilizing a reciprocatory piston movement for applying an impact force on to a working surface including a casing (1) having disposed axially therein a hammer member (12), an anvil (5) impacted by the hammer member and a chisel point (4) supported by the anvil. A spool valve (18) is located within the interior of the hammer member for reciprocatory movement in unison with the hammer member, the control the flow of a pressurized working fluid supplied to the hammer member, to thereby cyclically move the hammer member in reciprocatory movement.

Abstract: A hand tool in the form of a pneumatically actuated mallet. The tool comprises a conventional pneumatic motor of the type employed in pneumatic fastener driving tools, including a tool body having a main cylinder, a piston/driver assembly, trigger-actuated control valve means, and means for connection to a source of air under pressure. A guide body is affixed to the tool body beneath the main cylinder and has a longitudinal bore to slidably guide the driver. A housing is supported by the free end of the guide body and comprises a closed first end adjacent the guide body with a perforation for passage of the driver therethrough, a peripheral wall and an open second end. A mallet is provided having a body portion and a slightly larger head portion with a shoulder formed therebetween. A retainer is affixed to the housing wall partially closing the second end of the housing. The mallet head portion is reciprocally mounted in the housing with its body portion extending through an opening in the retainer.

Abstract: A pneumatically-actuated multi-needle type chisel tool is provided having a hollow cylinder body, a piston ram fitted for axially reciprocal movement in a rearward portion of the cylinder body, an anvil fitted for axially reciprocal movement in an intermediate portion of the cylinder body, a needle holder fitted for axially reciprocal movement in a forward portion of the cylinder body and a number of needle chisels journaled for axially reciprocal movement in the needle holder. A first air passage is provided with an opening into the rearward portion of the cylinder body to introduce compressed air thereinto for moving the piston ram to and fro. A second air passage is provided with an opening into the forward portion of the cylinder body to introduce compressed air thereinto for moving the needle holder rearwardly.

Abstract: A percussion tool comprising a housing; a tool bit movably supported by the housing for alternatingly executing forward and recoil strokes; a hammer piston supported in the housing and arranged for delivering consecutive blows at least indirectly to the tool bit for effecting the forward strokes thereof; a dampening chamber in the housing; an arrangement for introducing fluid into the dampening chamber for generating a dampening force therein; and a dampening piston supported in the housing and bounding the dampening chamber. The tool bit is connected with the dampening piston for effecting an axial displacement of the dampening piston into the dampening chamber by the tool bit during the recoil strokes thereof. There is further provided a control arrangement carried by the dampening piston for varying the dampening force of the fluid in the dampening chamber as function of a relative axial displacement between the dampening piston and the housing.

Abstract: A chuck is used with a hammer drill having a drive spindle rotatable about a spindle axis and a hammer displaceable axially in the drive spindle, and with a drill bit having a shaft extending along a shaft axis and having a radially outwardly open and at least generally axially extending groove. The chuck has a generally tubular chuck body centered on a chuck axis and having a central axially extending passage. This body is normally carried on the spindle and receives the shaft of the drill bit in its passage with the spindle, shaft, and chuck axes all coaxial. The hammer projects axially forward into the passage and is engageable therein with the bit. A plurality of jaws radially but not angularly displaceable in the chuck body have inner ends engageable with the drill-bit shaft and in turn provided with formations complementarily engageable in the groove thereof.

Abstract: A foot assembly for an impact tool reduces tool bit rebound shock to the operator and minimizes tool bit bouncing on the work surface by isolating and attenuating energy reflected from the work surface through the tool bit. The unique system comprises a collar support fabricated from a tough elastomeric material, which engages the inserted inner end of the tool bit and is maintained firmly against the collar thereof by a coil spring. Mounted inwardly within the longitudinal passageway of the foot assembly housing is a bushing, which has an outer contact surface against which the collar support will be thrust by the inwardly moving bit, the elastomeric material thereby serving to attentuate the rebound energy.

Abstract: A device for punching holes of varying size in sheet metal by a pneumatic hammer. A tapered punch is employed with an adjustment at the muzzle end of the hammer which selectively limits the travel and penetration of the punch thereby determining the size of the hole. A special attachment for the tapered punch and a punch holder for the punch is provided for attachment to the muzzle end of the pneumatic hammer. The attachment is in the form of a housing which receives the punch and punch holder and can be screwed on the muzzle end of a pneumatic hammer and present the punch holder to the internal hammer like drive of a conventional pneumatic hammer.

Abstract: A power hammer for driving piles and the like which includes a housing having a ram carried therein for reciprocating vertical movement to strike, during its downward movement, an anvil slidably carried within the lower portion of the housing. The portion of the housing in which the anvil is carried is formed with an annular recess, and the anvil includes an annular flange projecting into the recess to form an enclosed chamber beneath such flange. Air pressure generated by the ascendency of the ram is transmitted to the enclosed chamber to impose an upwardly directed force on the anvil whereby the weight of the anvil is utilized to oppose the upwardly directed force imposed on the power hammer during the ascending movement of the ram.

Abstract: A tool shaft, especially for drills of the percussive type, such as hammer drills, is adapted to be mounted in a tool holder having fixed driving elements, and the shaft is therefore provided with guiding recesses driving recesses and interconnecting transition recesses which recesses in combination with the driving elements form a type of bayonet joint.In order to improve the universal applicability of the tool shaft also in connection with tool holders of the type having radially movable driving elements, the driving recesses are formed with a radial depth exceeding that of the guiding recesses, and each of the guiding recesses has a cross-sectional shape so as to define a rib or edge between each associated pair of guiding and driving recesses so as to prevent spherical or cylinder shaped driving elements of the radially movable type from being moved unintentionally from the driving recess into the associated guiding recess.

Abstract: In a tool holder for securing a tool in a hammer drill in a form-locking manner, locking elements are radially displaceably mounted in a guide member. An adjustment ring is threaded onto the guide member and by rotating the adjustment ring relative to the guide member, the locking elements can be adjustably tightened or loosened. The locking elements seat in closed end recesses in the shank of the tool to be secured. The adjustment ring can be locked in different rotational positions by an interlocking tooth arrangement. Teeth are provided on the adjustment ring and on a fixing sleeve axially slidably positioned on the guide member. The fixing sleeve can be moved axially between a position for locking the adjustment ring and another position permitting the adjustment ring to be rotated relative to the guide member.

Abstract: A hand-held motor-driven percussion tool comprises a piston driven over an air cushion and acting over an axially movable anvil on the inner end of a tool axially movable in a tool receiver provided at one end of a tool housing. The anvil has an annular collar located in the cavity of an impact body which is movable in the direction of the impact of the piston against a cushioning ring. The impact body has an abutment face adapted to be engaged by a collar of the anvil when the latter is driven by the piston. A face of the impact body facing away from the cushioning ring is directed toward a part fixedly connected with the tool housing. The mass of the impact body is for instance 10% greater than that of the anvil. If the tool during operation is withdrawn from a workpiece, then the flange of the anvil impinges upon the abutment face of the impact body and accelerates the latter towards the cushioning ring.

Abstract: A percussive drill has a bit holder, a percussive drive including a ram slidably mounted in a hollow piston, and a drive transmission for reciprocating the ram in the piston via an air cushion. The forward travel of the ram during percussive action of the drill is limited by a drill bit or an intermediate member interposed between the drill bit and the ram. A member holds the ram in a position further forward, than that attained during the above limited travel allowed the ram, when percussive action is not desired. The holding member is resilient, has a U shaped cross-section, and is entered by the ram as it moves to the further forward position, the ram then forming a seal therewith, and the member also functioning to absorb the energy of an impact by the ram.

Abstract: A hammer drill for performing percussive drilling or rotary drilling includes a housing and a tool holder mounted on and axially displaceable relative to the housing, the tool holder contains a retainer sleeve mounting locking member for securing the shank of a tool in the holder. When the hammer drill is used only for rotary drilling, the retainer sleeve is displaced into contacting engagement with the housing for centering the tool holder. The tool holder includes stops for securing the locking members against axial displacement during rotary drilling. One stop is movable relative to the retainer sleeve and can be locked in position. Another stop forms part of the retainer sleeve. The stops combine with the closed ends of the recesses in the tool shank for holding the locking members against axial displacement.

Abstract: The operator of a taphole drilling apparatus for blast furnaces performs manual changes on the apparatus in its safe position of rest and operation by remote control and automatic latching in hazardous taphole work including drilling and subsequent driving, release, and extraction of a tap bar. The usual guide rail (22) carrying reciprocably a hammer drill (30) thereon incorporates a remotely openable automatically latching centralizer (42) at its forward end and an extraction carriage (29) on which, after removal of the drill steel (43), an impact sleeve (50) can be manually mounted for being impacted by the hammer drill (30). In one mounting position (FIG. 5) of the impact sleeve (50), a latch (57) therein is biased to automatically latch the shank of a tap bar (53) thereto for extraction by impacts. In a 180.degree. counter-turned position the latch (57) will fall aside and the mounted sleeve (50) is used to drive the tap bar while guided by the centralizer (42).

Abstract: A casing hammer for simultaneously driving casing and drilling a water well comprises a housing having an annular pneumatic chamber with an annular piston that drives an annular anvil which seals the lower end of the chamber. The chamber is formed by outer and inner sleeves of which the inner sleeve is fixed to an end cap solely at its rear end and is thus cantilevered from the end cap, being free of connection at its forward end. The forward end of the inner sleeve is stabilized by means of a relatively small clearance between the anvil and the sleeves at the front end of the chamber. The cantilevered connection of the inner sleeve at its rear end provides a smooth and unobstructed bore through which extends a rotating drill string that also extends through casing while the casing is being driven by the annular hammer.

Abstract: A wheeled, self-propelled apparatus has a percussion tool or hammer mounted on its forward end and an impact transmitting means carried on the tractor below the hammer. The impact transmitting means is adapted to be mounted to transmit repeated impacts from the hammer to a cemetery marker until the latter is flush with the ground surface where it will not interfere with ground maintenance, such as lawnmowing and the like.

Abstract: A pneumatic system includes a pneumatic motor, which may take the form of a vibrationless paving breaker utilizing a blow-striking member or hammer that is propelled to and from its force-transmitting or blow-striking position by a compressed gas. A valving arrangement provides for relatively large-ratio expansion of the compressed gas in the space under the hammer between its infeed thereinto and its exhaustion therefrom, in order to significantly utilize heat energy in the compressed gas to assist in energizing the propulsion of the hammer. Such heat energy is usually invested in the compressed gas by and during substantially adiabatic compression thereof at a gas-volume transformer, or compressor, included in the pneumatic system. It may be noted that the process of substantially adiabatic compression in the compressor is to a significant degree reversely duplicated in energizing the propulsion of the hammer.

Abstract: A guide framework for guiding a hammer in driving piles into subaqueous ground, said framework comprising a socket slidingly engaging the pile by means of a passage and at least one guide stay secured to the socket for guiding the hammer, the guide stay of said framework being detachably secured to the socket. As a result parts of the guide framework can be changed and the quantity of steel to be kept on stock for guide frameworks is small.

Abstract: A driver assembly for reliably driving relatively small-diameter washered and nonwashered fasteners from an indirect-acting powder-actuated tool comprises an adapter, carried on the muzzle end of the tool barrel and having a bore wherein is operatively disposed an adapter piston adapted for cooperation with the tool piston. The adapter bore comprises two portions: a first portion, of a size to slidingly admit the shank of the tool piston, and a second portion, having a diameter of a size to guide and support the fastener during driving thereof. The adapter piston includes a head slidingly fitted in the first adapter bore portion and a shank so fitted in the second bore portion. The adapter piston is preferably spaced apart from the tool piston when both are in the driving position, whereby tool recoil is reduced.

Abstract: A casing hammer for driving casing while drilling a water well comprises a housing having an annular pneumatic chamber with a relatively lightweight, short-stroke annular piston. The piston is reciprocably driven at a high rate to provide a large number of light blows of controllable energy upon an annular anvil that seals one end of the chamber. Percussive blows upon the anvil are transmitted through a drive head and adapter to the upper end of the pipe to be driven. The hammer is suspended from a rotary drive head that operates a hollow drill string extending downwardly through the hammer and through the casing driven thereby.

Abstract: A power hammer having an elongated hammer element disposed in a tubular housing for reciprocating motion therein and having a cylindrical cam concentrically mounted with respect to the tubular housing for displacing the hammer element against the force of a compression spring. When a point in the cam profile is reached which drops off abruptly, the hammer element is driven against an anvil member also disposed in the tubular housing. The cam is adapted to be driven by either an electric motor or another suitable source of rotational power.

Abstract: A driver tool of the power hammer type is equipped with a compression spring acting on the anvil of the tool and loaded by the weight of the tool and by downcrowding to store energy from the load and from attempted rebound of the anvil which is released to the anvil in a driving direction adding to the driving force of the hammer. The spring has a stiffness and a length effective to maintain a free stroke length for the hammer before impacting the anvil when the tool is loaded or downcrowded sufficiently to maintain the anvil thrusting against the workpiece and to develop and build up vibrations from the hammer blows. The hammer blows are divided into impulses by the vibrations allowing the workpiece to recover from blows of magnitudes beyond the elastic limit of the workpiece material which would otherwise damage the workpiece.

Abstract: A hammer drill has a movable tool and a driving element substantially coaxial with the tool. The driving element directly transmits axial impact from the same to the tool without transmission of torque. A tool holder surrounds proximal end portions of the driving element and the tool and transmits torque from the former to the latter without transmission of axial impact. Drive means are provided for selectively imparting torque and/or axial impact to the driving element. The tool holder comprises a sleeve which surrounds the proximal end portions. The sleeve is axially movable relative to the driving element and the tool and, at the same time, are connected with them for joint rotation therewith. An additional sleeve is provided surrounding the sleeve and enabling an operator to hold and to guide the hammer drill.

Abstract: The combination of a pile driving apparatus having a hammer operating mechanism mounted above a downwardly extending pile sleeve having an internal cross-section dimensioned to receive the top of a pile of a first diameter, whereby the apparatus may be guided onto and supported on the top of a pile, with an adaptor fitted within the pile sleeve and having an internal cross-section dimensioned to receive the top of a pile of smaller diameter than said first diameter, said adaptor being fabricated as a unit and the adaptor unit and pile sleeve being interconnected preventing withdrawal of the adaptor unit from the pile sleeve.

Abstract: An impact device, incorporating power drive means having a resilient drive element for generating successive ram impacts against a tool by reaction of the resilient drive element against the device frame, incorporates resilient bias means, interposed between the frame and the tool, to continuously transmit bias force from frame to tool acting to hold the tool firmly against a workpiece during operation, while resiliently suspending the frame for free dynamic motion clear of motion limiting stops, thereby eliminating spurious tool and frame motions and directing the impact energy of the ram to more efficiently and effectively accomplish impact work.

Abstract: A self-propelled pnuematic burrowing device having an axially reciprocating percussion plunger arranged inside a tubular casing so as to strike a percussion head at the forward extremity of the casing, thereby advancing the device through the ground by crushing and/or displacing the material in the path of the device, the percussion head being freely displaceable between axial abutments defined by a guide sleeve of the casing, the displaceability being slightly in excess of the advance of the device per stroke and adjustable through the insertion and removal of split spacer rings. The air controls of the device, located in the rear portion of the casing, include a control barrel with an enlarged control head and a gradually widening central air supply channel.

Abstract: A pneumatically operated impact drilling tool for earth drilling, includes a reciprocating hammer, an anvil positioned under the hammer and a feeder tube extending through the hammer and at least partially through the anvil. The drilling tool is connected to a string of drilling pipe and high pressure compressed air or other pneumatic fluid is introduced to operate the tool. The feeder directs the flow of fluid through ports in the hammer to alternate pressure on opposite sides of the hammer to move the same upward and downward relative to the anvil. A venturi arrangement in the feeder tube functions to produce a vacuum which is applied to the opposite end of the hammer from the end at which pressure is being applied for moving the same.

Abstract: The application discloses an explosive-cartridge powered hammer or impact tool, which is especially adapted for use in foundries for trimming or finishing castings by knocking off runners, feeder heads and flash, but which can also be used for other operations, such as riveting. The hammer is provided with means to soften recoil.

Abstract: A hammer and more particularly a fluid operable hammer wherein alternating impetus provided by pressurized liquid and gas means actuates a reciprocable hammer piston to generate repetitive impact loads. A work member is provided to receive blows from the hammer and includes an enlarged portion located in a sealed, variable volume cushion chamber. Means are provided to provide fluid above atmospheric pressure in the chamber. The chamber is sealed before hammer operation to provide a variable gas pressure cushioning chamber for the work member.

Abstract: A relatively quiet-operating rotary hammer for use in apparatus for securing T-edging and similar edging bands. The hammer includes a pivoted hammer head that is intermittently and continuously impacted to provide a hammering action. The hammer is impacted by a rotary structure carrying spaced hammering elements for forcibly pivoting the hammer head.

Abstract: A pile driving device comprises one or more guide stays, a Diesel hammer, consisting of a combustion cylinder guided by guide means along each guide stay and a hammer piston operating in said combustion cylinder.Lifting the hammer piston at the start of the known pile-driving device takes place by means of a cable of a winch arranged at a large distance. In order to facilitate the starting the hammer piston is lifted by means of a hydraulic cylinder-piston set which via a catch engages the piston on the one hand and the combustion cylinder on the other hand.

Abstract: In a Diesel pile-driving ram comprising a combustion cylinder, a striker extending into the combustion cylinder, a piston housed in the combustion cylinder and a fuel injector for the supply of fuel between the impact surfaces of the piston and the striker, the impact surface of the striker is orientated in such a manner towards an annular precombustion chamber of a compression space provided between the piston and the striker, that the fuel atomized by impact ignites in the precombustion chamber. Said fuel, however, has too little air in said chamber in order to ignite immediately. The ignition is delayed for a moment but not too strongly because the precombustion chamber communicates with the main combustion chamber through an ample, annular passage of short length in an axial direction.

Abstract: A housing has a tool mounted therein so that a portion of the tool can slide for reciprocatory movement deeper into and farther out of the housing. A prestressed biasing spring or a cushion of gas is interposed between and acts upon the housing and the aforementioned portion of the tool, being prestressed to an extent which is less than the minimum force with which the tool can engage a workpiece when the tool is pushed against the workpiece by the weight of the hammer, and which biasing means has a flat spring characteristic.

Abstract: A portable hydraulic actuated machine for driving posts, ground anchors, concrete breakers, core drills and the like work pieces into the ground, pavements, or wall structures, maintains a continuing thrust on the work piece amplified by sequential hammer blows of controlled magnitude to advance the work piece at a rapid rate without damage to the impact receiving end of the work piece. The machine includes an automotive vehicle which is easily transported to the work site and which carries a turntable supporting an upstanding tower on which rides a carriage slidably mounting a spring loaded heavy hammer, a work piece engaging spring loaded anvil struck by the hammer and hydraulical hammer lifting mechanism. The tower is easily raised and lowered, adjusted toward and away from the vehicle and tiltable laterally to present the hammer and anvil to the work piece at the exact desired location in the plane of the work piece.