Abstract: The fluid-powered, reciprocating motor includes a cylinder having an inlet chamber and an outlet chamber, a differential area piston mounted in the cylinder, and an output or power shaft connected to the piston. A pressurized fluid, either a gas or a liquid, is continuously introduced into the cylinder inlet chamber and acts on the smaller piston area to move the piston in one direction. A small stream of the fluid flows from the cylinder inlet chamber into the cylinder outlet chamber through a control passage in the piston and is exhausted from the cylinder outlet chamber through an outlet passage until the piston is moved far enough for a valve member carried by the piston to close the outlet passage. Fluid pressure subsequently building up in the cylinder outlet chamber acts on the larger piston area and moves the piston in the opposite direction.

Abstract: A hydraulically operated impacting device includes a differential piston slidably disposed in a bore, and having an impacting surface and a piston rod facing at the other end a valve sleeve circumscribing the piston rod, there being an annular space between the rod and the valve, the valve having a first and a second position; a first duct leads from a pressure source to the bore and is governed by the valve for acting or not acting on the larger one of the two piston surfaces respectively in the first and second positions of the valve; a second duct leads from the source to the bore for acting on the smaller one of the piston surfaces; a third duct leads from the bore at a location below the valve to a ring chamber adjacent the valve, the valve having a collar which is movable in the ring chamber, the piston has a portion which depending on the position of the piston permits or prevents communication between the annular space and the third duct to obtain or not obtain pressurization of the ring chamber for s

Abstract: A drywall tool provides tactile and audible feedback to the user, as a fastener is driven by frequent multiple blows, to indicate when the fastener is properly driven, and the drywall dimpled, without tearing the paper facing of the drywall. Dimpling apparatus and a firing valve for controlling the multiple blows are described. A cam is provided to withdraw the magazine follower from the last fastener in a strip to avoid jamming or damage by a descending driver. Tool apparatus permits use of lightweight, synthetic parts.

Abstract: An asymmetrical vibrator is provided, which is actuated by compressed air. The vibrator operates in a case, which has two bores disposed parallel on opposite sides of the casing. One of the bores is smaller than the second bore and the piston operating in the small bore is called the slow piston, since it is actuated with air to a relatively slow motion and the piston operating in the second larger bore is called the fast piston, since it is moves at a larger speed when driven directly by the compressed air. The asymmetric vibration motion can be employed to transport materials upwardly in factories and assembly stations. The air operated asymmetric vibrators need low maintenance and do not entail the spark dangers caused by the presence of electrical wiring for electrical drive motors.

Abstract: A cylinder (15) is reciprocable in the housing (11) of a hydraulic percussive tool and a piston hammer (16) is reciprocable in the cylinder. The force between the cylinder and the housing is constant during the cycle of reciprocation and as a result the housing (11) is practically not vibrating at all. The piston hammer (16) and the cylinder (15) are coupled together to move conjointly during a part of each forward stroke of the hammer piston, which ensures the timing of the reciprocation of the hammer piston 16 and the cylinder (15).

Abstract: A downhole hydraulically actuated pump assembly of either the free or fixed type lifts formation fluid from the bottom of a borehole to the surface of the ground. The downhole pump has a power piston which actuates a production plunger. A valve means is concentrically arranged within the power piston. A stationary, hollow valve control rod extends through the power piston and through the valve means, with a lower marginal end of the control rod terminating within the production plunger. Power fluid flows through the control rod and to the valve means. As the power piston reciprocates within the engine cylinder, means on the control rod actuates the valve means between two alternant positions so that power fluid is applied to the bottom face of the power piston to thereby cause the power piston to reciprocate upward; and thereafter, the control rod causes the valve means to shift to the other position, whereupon spent power fluid is exhausted from the engine cylinder.

Abstract: A control device for working cycles of a self-propelled pneumatic boring device with a non-rotatable axially displaceable impact piston controllable by control edges of a control sleeve supported axially non-displaceably but rotatably and at its front end forming a control head with the control edges. The control head engaging in a cylindrical recess at a rear end of the impact piston cooperates with a radial main control opening formed in the impact piston in the vicinity of the recess. The control edges form two different pairs of the control edges, offset peripherally as well as axially such that respectively in one rotated position of the control sleeve only one of the pairs is aligned for cooperation with the main control opening. The impact piston is formed with at least one additional control opening which cooperates with the other pair and has a flow cross-section considerably smaller than that of the main control opening.

Abstract: A valveless, pneumatic motor including a cylinder within which a hammer piston reciprocates and a buffer ring fixedly secured within the cylinder. A source of motive fluid under pressure cooperates with the buffer ring which through supply porting provides pressurized motive fluid alternately to opposed faces of the piston head. Intake ports are formed within the piston stem and adapted to cooperate intermittently with the buffer ring supply porting to provide motive fluid to the piston interior wherein an axial bore transmits the fluid along the stem toward the piston head and discharge porting delivers the motive fluid to the forward face of the piston head thereby urging the piston rearwardly. A reduced diameter portion of the piston stem then comes into communication with the buffer ring supply porting and permits the motive fluid to impinge directly on the rearward face of the piston head without passage through the piston to urge the piston forwardly.

Abstract: A liquid pressure striking device defines a double-acting cylinder in a main body thereof having a tool at its lowest portion, and the double-acting cylinder houses therewithin a piston having an upper rod and a lower rod. The lower rod suspends a hammer for striking the tool, and the upper rod is provided on its outer circumference with a change-over valve mechanism which comprises a valve body of special structure for automatically switching the liquid flow under pressure by vertical movement of the piston, and a valve chamber having a plurality of concaves for controlling said valve body. Above the upper part of the valve chamber, there is provided an accumulator serving as a cap or cover of the main body. The main body is formed with an inlet passage of the liquid and an outlet passage, communicating with the accumulator and the valve chamber.

Abstract: This invention pertains to a fluid actuator having piston chambers, a piston maintained within said chambers, a valve means for reciprocating the piston and a pressure control means for varying the force to the valve means wherein the reciprocating frequency of the piston is modulated.

Abstract: A reciprocation valve for a hydraulically actuated reciprocation motor, wherein the motor has hydraulic inlet and outlet passages into a cylinder through a porting block, and a slidable collar is fitted over the porting block for selectively opening and closing the passages, and a lightweight carriage assembly is attached to the collar and is actuated by a trip rod coupled to a piston within the cylinder.

Abstract: This hydromechanical automatic reversing device for linear hydraulic rams operates by inertia and comprises a support block mounted to the ram body, a pendular arm pivoted at one end to the spool of the reversing valve associated with the ram, and, at the opposite end, to an eccentric pin trunnioned in the support block. A shaft rigid with and parallel to the ram piston rod is provided with a pair of adjustable stops adapted to engage by turns the eccentric pin of the pendular arm for shifting the spool of the reversing valve, for reversing the direction of movement of the ram.

Abstract: A hydraulically operated impact motor, e.g. for a jack hammer, has a hammer piston that has a piston surface 19 in a pressure chamber 21 which is constantly pressurized in order to effect the work strokes of the hammer piston, and a larger piston surface 20 in a second pressure chamber 21 which is intermittently pressurized in order to effect the return strokes of the hammer piston. The second pressure chamber 22 is also connected to the exhaust line via a one-way valve that permits flow towards the second pressure chamber 22.

Abstract: A fluid actuator housing (40) supports an output member 56 and a valve assembly (62). The valve assembly controls fluid communication to a pair of chambers (58, 60) to reciprocate the output member within the housing. The first part (64) of the valve assembly directs fluid communication to the chambers and the second part (66) is engageable with the output member to control movement of the first part.

Abstract: An oscillator actuated hydraulic impulse of the type including a spool valve actuated by an alternating signal from an oscillator to switch the hydraulic pressure in a double acting cylinder in order to cause reciprocating motion of a piston which strikes a boring tool. The hydraulic impulse device further includes a means for controlling the transition from the impulse stroke to the return stroke of the piston. In some embodiments, the hydraulic impulse device may further include a means for varying the duration of the impulse stroke and the return stroke of the piston.

Abstract: An impactor apparatus including novel means for actuation of a motive fluid flow control valve or comparable motive fluid control means.

Abstract: Control device for the forward movement and rearward movement of self-driven pneumatic ram boring devices with an impact piston which is axially displaceable between two abutments in a tubular housing, with the axial forward movement and rearward movement of the ram boring device being controllable by rigid control edges of an adjustable control sleeve, the latter being supported on a bearing ring arranged in the rear part of the housing. Through the bearing ring there is led a part of the control sleeve forming a feed tube for the compressed air for connection to a compressed air hose, the sleeve having a piston-like control head containing the control edges; the control head engaging in a cylindrical recess at the rear end of the impact piston cooperates with radial control bores which are formed in the area of the recess in the impact piston. The control sleeve is mounted non-displaceably in the axial direction however rotatably in the bearing ring and is provided with at least four control edges.

Abstract: A pressure detecting device for detecting air pressure by means of a pressure receiving member which is energized by a coil spring, wherein a seal is provided between the side wall of the detector housing at the pressure detecting port side and the pressure receiving member as well as between the other side wall of the housing at the discharge port side and the pressure receiving member and further sealing area at the discharge port side is larger than that at the pressure detecting port side.As a preferred application of the pressure detecting device a control system for a press machine is constructed such that operation and stop of the press machine are controlled by way of controlling supply and discharge of pressurized air to and from the press machine with the aid of a double valve and the pressure detecting device.

Abstract: The invention relates to a thrust device using a plurality of hydraulic jacks, and to the automatic control of a plurality of thrust jacks.Two differential jacks have resetting chambers which are permanently under hydraulic pressure. Associated with each jack there is a self-locking piloted valve placed in the active position by a push-rod at the end of a work stroke of the piston of the jack and restored into the inactive position by a piloted valve actuated by a push-rod 39 at the end of the return stroke of the piston to its starting position. In the active position the self-locking piloted valve controls the isolation from the supply of all the work chambers and the venting of the associated work chamber 14.

Abstract: A cylinder control device of a hydraulic cylinder apparatus including a main directional control valve having a pilot chamber for controlling the reciprocatory movement of the piston, and a first valve including a plurality valve members for selectively communicating the pilot chamber, via an auxiliary directional control valve, to the fluid discharging tank side of the working fluid circuit when the piston reaches a predetermined position in its rearward stroke. The pilot chamber is brought into communication, via a passage, to the pump side of the working fluid circuit by a second valve when the piston reaches the end of its forward stroke. A control valve using the pump side pressure as a pilot pressure is mounted in the passage connecting the second valve to the pilot chamber or in the passage connecting the pilot chamber to the auxiliary directional control valve.

Abstract: A hydraulic impact device in which a hammer member having a piston portion is reciprocally disposed in a cylinder, a reciprocating sleeve valve is disposed within the cylinder and surrounds the hammer member. The sleeve valve has a first peripheral seal with an upper portion of the cylinder and a second peripheral seal with the lower portion of the cylinder so that an annular cavity is formed between the first and the second peripheral seals. The bottom portion of the sleeve valve forms a single seal with the upper portion of the piston section. A pressure relief valve is situated between the inlet to said annular cavity and an annular cavity below the piston portion to insure that the pressure in said annular cavity is greater than the pressure in the cavity below the piston portion and the sleeve valve thus effecting a sealing force between the sleeve valve and the upper face of the piston portion. An energy storage means is provided for receiving energy from said ram member during its upward stroke.

Abstract: A fluid arrangement for the alternating operation of an apparatus includes a working cylinder with a working piston endowed with an alternating movement and a control cylinder with an alternatingly moving control piston. Each of the cylinders has for the respective piston a driving chamber which is alternately connected to a supply source of fluid under pressure and to a discharge opening for the fluid through a distributor, and a return chamber permanently connected to the supply source of fluid under pressure. The distributor connected to the driving chamber in the working cylinder is the control cylinder, and the distributor connected to the driving chamber in the control cylinder is the working chamber.

Abstract: A high torque hydraulic power plant is operated by electrical power through the use of a hydraulic pump, opposing double-ended cylinders containing double-ended pistons and appropriate cycling valve means. Pressure is maintained in the system by a constant pneumatic force applied to the full piston side of each opposing double-ended piston.

Abstract: A hydraulically-operated road breaker comprises a casing with a tool mounting and housing an oscillatory piston/striker and cylinder arrangement. A sequence valve mounted in the casing controls pressurization and exhausting of the piston to produce power and return strokes of the piston. Pilot port means positioned in the cylinder of the device are uncovered, at the end of each return stroke of the piston, to allow a valve-actuating flow of hydraulic fluid through the port means to change over the sequence valve and thereby cause stroke reversal of the piston. Manually-operable stroke selection means provide for adjustment of the position of the piston in the cylinder at which the valve-actuating flow occurs, whereby to vary the piston stroke.

Abstract: A solenoid operated metering pump for displacement of exact amounts of fluid pumped by reciprocation of pumping piston incorporating integral check valve has an elongated valve housing with solenoid operator serving as pump actuating means attached to one housing end while the other housing end is adaptable to serve as the fluid pumping means including an appropriate housing bore passing therethrough and adaptable to receive a differential diameter piston assembly slidably movable therein to reciprocate when solenoid operator becomes electrically cycled inducing fluid flow through appropriate pump chamber created therein between piston and housing bore portion provided with fluid supply port having a detachable check valve with a simple floater for a directional flow control therethrough, means of piston actuation from a first position checking flow and discharge of the fluid delivered to the pump chamber to a second position discharging exact fluid quantity per each stroke of pump reciprocation, and means of

Abstract: A hydraulic percussion or an impact apparatus for driving rock-breaking tools, drill bits and ramming or tamping tools comprises a body in which an end of the tool is received and a reciprocating mass formed as a piston which is axially displaceable in a cylinder. The cylinder is provided with a distributor member slidable above the piston and of the same diameter as the latter, the distributor being formed as a sleeve having a central portion engaging a collar of a plunger which extends into a piston and forms therewith a suction chamber. The plunger has an extension which is slidable in a bore of the body and is acted upon by the high-pressure fluid.

Abstract: A rock drill having a hydraulic pressure reservoir formed by the drill housing, and an anvil rotation mechanism enclosed in the housing. A piston of substantial length and a mechanical hydro-operated valve means, provide favorable pulse duration and low impact velocity. The piston has only two sliding seal diameters which permits simplified valve and cylinder configuration. The friction surfaces of the fronthead drill assembly are lubricated and cooled by integration with the circulating hydraulic system. A floating seal cartridge between the piston and anvil, tends to rotate the piston with the anvil to minimize rotative scrubbing at impact.

Abstract: Hydraulic actuation of a device for delivering impact energy to a load, such as a pile driver, is provided by a hydraulically operated oscillator having a piston which is reciprocal in a cylinder under hydraulic forces developed by pressurized hydraulic fluid in the cylinder which is switched from supply to return pressure by a valve. The valve is actuated between switching positions by means of trip ports opened and closed by spaced flats on a rod which connect the piston to an impact delivering member, such as the ram of the pile driver. The trip ports are connected to the valve for applying pressurized hydraulic fluid either at supply or return pressure thereto so as to shift the valve between the switching positions. The valve is bi-stable in either of its switching positions through the use of latching ports and restricted passageways through which hydraulic fluid flows in amounts sufficient to make up for leakage through the valve which would otherwise allow the valve to drift.

Abstract: A fluid operable hammer including variable volume exhaust fluid receiving chamber means cooperable with improved motive fluid inlet and exhaust valve means.

Abstract: A hydraulically-operated percussive device comprises a piston/striker reciprocable in a housing and valve means adapted to intermittently pressurize a working area of the piston/striker to produce forward working strokes thereof. The housing contains a chamber adapted to be pressurized by the hydraulic working fluid to apply a continuous return force to a differential return area of the piston/striker which has a step arranged to enter a dashpot cavity at one end of the chamber to damp forward movement and thereby limit overstroking of the piston/striker. The piston/striker has an intermediate flanged portion which is a close sliding fit in the chamber end regions of which are interconnected through a conduit so that both annular end faces of the flanged portion are subject to the fluid pressure. The end faces are of different efective areas with the difference providing said differential return area and the larger end face providing the step.

Abstract: An impact tool is described which is capable of developing percussive forces for rock drilling, pile driving, seismic exploration and other repetitive high force applications. The tool contains a hammer and a valve which may be hydraulically actuated so as to oscillate; repetitively executing forward and return strokes during each cycle of oscillation. The valve is actuated in the forward stroke direction by being engaged by the hammer, and in the return stroke direction by fluid pressure means so as to switch the pressure in a cavity in which both the valve and the hammer are disposed for developing forces on the hammer so as to sustain its oscillation. A fluid filled pocket is provided into which the valve enters as it moves in the forward stroke direction, after having switched the pressure in the cavity. A passage is provided on the hammer which is dimensioned so that fluid in the cavity is either connected to a channel, the cavity, or entrapped in the pocket, depending on the position of the hammer.

Abstract: A hydraulically operated reciprocating piston and a differential force operated valve are both in continuous fluid contact with a pressurized cushion chamber as well as the piston chamber pressure. The valve position is a function of the cushion chamber pressure. The cushion chamber pressure is a function of the axial position of the piston. The values of these functions are such that the piston is reciprocated when the machine is operated. The valve may, for example, be a sleeve coaxial with the piston or a valve transversely spaced from the piston.

Abstract: The invention provides a hydraulically-driven reciprocatory tool comprising piston with a shoulder reciprocable in a cylinder, and a shuttle valve for controlling supply of fluid to a first face of the piston, the fluid producing a force on the first face which is alternately greater than and less than a constant bias force applied to a second face of the piston, wherein the position of the shuttle valve is determined by the pressure of fluid in a fluid connection between the shuttle valve and first and second ports in the wall of the cylinder, the fluid connection including a first non-return valve for preventing flow of fluid from one of the ports to the shuttle valve and a second non-return valve for preventing flow of fluid from the shuttle valve to the other of the ports. Preferably, each non-return valve has associated with it a variable throttle in the fluid connection and further means are provided for controllable flow of fluid along a branch of the fluid connection.

Abstract: A downhole, hydraulically actuated pump assembly, having an engine reciprocatingly connected to a production pump. Power fluid is conducted downhole to the engine of the pump assembly, while production fluid and spent power fluid is conducted uphole to the surface of the ground.The pump assembly includes a housing within which spaced, axially aligned, cylindrical chambers reciprocatingly receive spaced engine and pump pistons which are connected together in a manner to enable the engine to reciprocate the production pump.A mechanically actuated valve assembly is contained within the engine piston and is arranged respective to various different flow passageways so that flow of power fluid through the engine forces the engine piston to reciprocate.The valve assembly includes a control rod and a valve element concentrically arranged respective to one another and to the engine piston. The valve element is reciprocated respective to the engine piston in response to the reciprocation of the control rod.

Abstract: A source of fluid, regulated as to pressure intensity before entry into a control valve assembly, drives a fluid biased piston motor. A mechanically actuated and fluid held valve in the control valve assembly controls pressurization of a pressure chamber in the piston motor displacing the motor piston through its return stroke. Pressure differential on opposite sides of a fluid operated valve actuator insures rapid opening of the valve and holding thereof in its open position during the motor piston return stroke. At the end of the return stroke, the pressure differential is eliminated to allow spring-biased closing of the valve and venting of the pressure chamber.

Abstract: In a hydraulic striking device having a reciprocating piston there are first and second cylindrical spaces surrounding the piston, the first space continuously communicating with a high pressure circuit and the second space alternately communicating with the high pressure circuit and a low pressure circuit. A special sleeve-shaped control valve in the second space reciprocates axially of the piston to achieve the desired operation.

Abstract: A hydraulically driven hammer is disclosed, along with valve actuation arrangements which operate to switch hydraulic forces on the hammer ram after preselected intervals following application of pressurized pilot fluid flows. These flows pass into a fluid accumulation chamber unitl a predetermined volume is accumulated after which continued pilot fluid flow produces valve actuation.

Abstract: Impact tools are described which are capable of developing percussive forces for rock drilling, seismic exploration and other repetitive high force applications. Each of the tools contains a hammer and a valve which may be hydraulically actuated so as to constitute a hydroacoustic oscillator. The valve is actuated in one direction by being engaged by the hammer and in the other direction by fluid pressure means. The fluid pressure means may be controlled by varying the fluid pressure magnitude which applies forces to the valve to effect the movement thereof so as to control the frequency of oscillation of the hammer (i.e., impact blow frequency). Control may also be provided over the hammer stroke and the blow energy.

Abstract: A striking apparatus has a body which carries a tool and which has a cylinder space, a piston structure within the space, and a sleeve-type distributor valve within the cylinder and around the piston. Flow of hydraulic fluid supplied to the body under pressure is controlled by the valve and piston to cause the piston to reciprocate, striking the tool. The sleeve valve has an extension portion which controls flow through a canal in the piston to a valve operating distributor space and limits flow of liquid under pressure to an outlet canal to a relatively short interval in the operating cycle, thereby reducing the amount of liquid wasted.

Abstract: A reciprocating pump for liquids has a shuttle valve for directing motive fluid alternatively to small- and large-area faces of a piston. The motive fluid directed to the small-area face acts as a spring for causing reciprocation.

Abstract: A hydraulic percussion tool for developing repeated impact blows for rock drilling and other high force applications is characterized by a piston hammer reciprocably disposed in a cylinder bore and a tubular valve member coaxial with and actuated by the hammer for controlling the flow of pressurized hydraulic fluid to and from portions of the cylinder bore. The valve member is actuated by the hammer on the return stroke thereof through a column of fluid trapped in an annular chamber formed between a transverse surface on the hammer and an end face of the valve member. Valving mechanism is operable to effect controlled venting of the trapped fluid from the annular chamber to change the position of the valve member with respect to the hammer and thereby control the hammer stroke length, impact blow, and blow frequency.

Abstract: An hydraulically operated striking apparatus for driving a rock drill or the like comprises a body having an axial, generally cylindrical, interior space with an inwardly protruding annular member. A cylindrical piston is positioned in the space in sliding contact with the protruding annular member, and the piston has canal means in its outer surface. The body, the annular member and the piston define two annular spaces and an annular distributing valve is slidably disposed within one of the spaces. The two spaces communicate with each other by means of the piston canal when the piston is in a first slidable position, and the protruding annular member prevents communication between the two spaces when the piston is in a second slidable position. The piston is provided with an axially disposed extension which, in combination with an outlet means, serves to permit a third, annular axial space to communicate with either an inlet means or an outlet means at all times.

Abstract: A hydraulically operated percussion apparatus comprising a housing in which a reciprocating impact piston is arranged to transfer impact energy to an impact tool, pressure chambers defined between said housing and said piston, and a channel system including a high pressure and a low pressure branch for conducting hydraulic pressure fluid to and from the pressure chambers, a first one of said chambers containing a movable distribution valve member responsive to the movements of the piston for alternately connecting said first chamber to said high pressure branch and said low pressure branch, respectively, characterized in that said valve member is arranged to be transported by the piston when moving in one direction, and responsive to the movement of the piston in the other direction to be acted upon by the pressure fluid to move in said other direction by means of hydrostatic pressure, said valve member having a longer path of movement than the impact piston and being arranged, at its movement in said one dir

Abstract: A hydraulically-operated reciprocatory device such as a road-breaking hammer includes piston means having an enlarged area portion which enters an overtravel-damping dashpot cavity. The dashpot cavity is in a chamber connected in series with valve means controlling the flow of hydraulic fluid such that said fluid flow through the chamber removes heat generated during a damping action.

Abstract: A hydraulically operable linear motor with a double-acting reciprocable piston in a cylinder, in which one side of the piston has connected thereto a piston rod so as to form with this one side an annular piston surface which is continuously exposed to a desired working pressure. The other side of the piston is by means of a hydraulically actuated control valve alternately exposed to the working pressure and to the pressure in an exhaust conduit. The pressure for actuating the valve spool of the control valve is generated in a conduit section which communicates with two annular grooves in the two cylinder sections separated from each other by the piston and adapted alternately to be closed off from the above mentioned conduit section. This conduit section communicates through throttles with the exhaust conduit.

Abstract: A hydraulically driven hammer is disclosed, along with valve actuation arrangements which operate to switch hydraulic forces on the hammer ram after preselected intervals following application of pressurized pilot fluid flows. These flows pass into a fluid accumulation chamber until a predetermined volume is accumulated after which continued pilot fluid flow produces valve actuation.

Abstract: A hydraulic impact device has a hammer member carrying a piston which is reciprocally disposed in a cylinder chamber to form an expansible chamber. When the expansible chamber is pressurized, the hammer is retracted against an air spring or other energy storage device by the high pressure. A sleeve valve is reciprocally disposed in the cylinder chamber between the piston and the energy storage device and is held against the piston by an imbalanced fluid pressure as the hammer is retracted against the spring. When the piston and sleeve valve have been retracted to a predetermined position, high pressure fluid is ported between the sleeve valve and piston to hydraulically separate the two members.

Abstract: This disclosure relates to a percussion tool which includes a housing having a chamber reciprocally mounting a piston with first and second pressure ducts at opposite ends of the latter and a control duct therebetween as well as a return duct in fluid communication with the chamber at a point intermediate the points of entry of the first and second pressure ducts and reciprocal valve means for controlling the reciprocal motion of the piston, the improvement including a plurality of branch ducts of the control duct opening into the chamber in such a fashion that the branch ducts are successively opened and closed during the reciprocation of the piston.

Abstract: Impact tools are described which are capable of developing percussive forces for rock drilling and other repetitive high force applications. A hydroacoustic oscillator contained in such tools includes a hammer and a valve mechanism which is actuated by the hammer for controlling the flow of pressurized fluid so as to establish pressure variations which sustain the oscillation of the hammer. A number of alternative valve mechanisms are disclosed, each including a valve element, the motion of which is controlled by controlling the flow of fluid with respect to the valve element as the hammer and valve element move relative to each other. Such flow control is afforded by chambers defined by the valve element; hydraulic fluid flow with respect to which is controlled so as to determine the deceleration of the valve element and the motion of the element in its actuation by the hammer.

Abstract: Impact tools are described which are capable of developing percussive forces for rock drilling and other repetitive high force applications. A hydroacoustic oscillator contained in such tools includes a hammer and a valve mechanism which is actuated by the hammer for controlling the flow of pressurized fluid so as to establish pressure variations which sustain the oscillation of the hammer. A number of alternative valve mechanisms are disclosed, each including a valve element, the motion of which is controlled by controlling the flow of fluid with respect to the valve element as the hammer and valve element move relative to each other. Such flow control is afforded by chambers defined by the valve element; hydraulic fluid flow with respect to which is controlled so as to determine the deceleration of the valve element and the motion of the element in its actuation by the hammer.