Abstract: A percussion apparatus driven by a pressurized incompressible fluid includes a body with two coaxial bores for slidably mounting of a tool, and separately slidably mounting a striking piston having a stepped configuration. A control device varies a stroke of the striking piston between a long and a short stroke, and is connected to the directional flow valve and to a bottom chamber of the piston cylinder. The control device includes a cylinder in which a spool is mounted. A first face of the spool is situated in a first chamber permanently subjected to a determined pressure, and a second face of the spool is situated in a second chamber connected to the braking chamber for controlling the varying of the stroke of the striking piston.

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: 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 hydraulic impact mechanism includes a housing with a cylinder bore, a forward working chamber and a rear working chamber, a hydraulic fluid supply passage connected to the forward working chamber and a drain passage connected to the rear working chamber, a hammer piston reciprocally guided in the cylinder bore for delivering blows to a working implement attached to the housing, a pressure accumulator pre-loaded to a certain pressure level, and a distribution valve for alternatingly connecting the rear working chamber to the supply passage and the drain passage to thereby reciprocate the hammer piston, wherein a sequence valve is provided in the drain passage to keep up the pressure in the rear working chamber so that the resulting forward directed force prevents the piston from being moved backwards in the cylinder bore at pressure levels in the supply passage below the pre-load pressure level of the accumulator.

Abstract: A double-acting hydraulic pressure intensifier includes a supply connection, a return connection, a high-pressure connection. An intensifier piston assembly includes a low-pressure piston arranged in a low-pressure cylinder and two high-pressure pistons connected to the low-pressure piston each arranged in a high-pressure cylinder. A switching valve assembly includes a displace able, hydraulically controlled valve element which on its two opposite sides in the direction of displacement has control pressure chambers with pressure application areas of different sizes, namely, a first control pressure chamber with a smaller pressure application area and a second control pressure chamber with a larger pressure application area. A stop plug is arranged between the second control pressure chamber and the supply connection.

Abstract: A hydraulic pressure intensifier includes a supply connection, a return connection, and a high-pressure connection. An intensifier piston assembly includes a high-pressure cylinder with a high-pressure piston displaceable therein and a low-pressure cylinder having a greater cross-section than the high-pressure cylinder, with a low-pressure piston which is displaceable therein. The low-pressure piston is connected to the high-pressure piston and divides the low-pressure cylinder into a first low-pressure chamber on the side of the high-pressure piston and a second low-pressure chamber. A switching valve acts on the second low-pressure chamber with pressure from a pressure source or relieves it of pressure.

Abstract: A pressure intensifier for fluids, particularly for hydraulic liquids, includes a piston/cylinder arrangement with a low pressure side provided with a low pressure connection and a high pressure side provided with a low pressure connection and a supply connection, as well as an intensifier piston constructed as a double diameter piston arranged between the low pressure side and the high pressure side. The pressure intensifier further includes a valve slide member which alternatingly connects the low pressure connection to a pressure source and a negative pressure source, wherein the control valve is connected through a control line to the piston/cylinder arrangement, so that the pressure in the control line acts on a first side of the valve slide member. The control valve is configured such that a constant force acts on a second side of the valve slide member.

Abstract: A hydraulically actuated breaker with a lost-motion preventing device includes a cylinder portion (26) defining a first chamber (23) constantly communicated with a hydraulic pressure source (47) and having a small pressure receiving area for upwardly moving a piston (22) and a second chamber (24) having a large pressure receiving area for downwardly moving the piston, by inserting the piston into a piston bore (21) of a breaker main body (20); a chisel (28) inserted within a chisel insertion hole (27) of the breaker main body in opposition to the piston; a main switching valve (40) being switched between a first position (E) communicating the second chamber with a tank (48) and a second position (F) communicating the second chamber with the hydraulic pressure source; and a valve mechanism (30) placing the main switching valve at the first position when the piston is in an effective lower stroke end position, placing the main switching valve at the second position when the piston is in an effective upper strok

Abstract: A hydraulically driven hammer has a piston which contains metal piston rings on a constant diameter section. The housing has a plurality of axially spaced apart radial ports that extend through the housing into the bore. A valve supplies fluid to the ports to control reciprocation of the piston.

Abstract: Hydraulic percussion hammer, in which a motion of a percussion piston (1) is controlled by a main valve (3), the control motion of which is controlled by a separate control valve (9) in such a way that the main valve changes its state, when the pressure acting on the control valve (9) rises to a predetermined value. The percussion hammer comprises a controller (21) mounted in its return duct (13), by which controller an outflow of pressure fluid from the percussion hammer can be adjusted in such a way that the filling rate of a pressure accumulator (7) and thus the length of a return motion of the percussion piston (1) are proportional to the flow resistance provided by the controller (21).

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

Abstract: A rock drill with a percussion mechanism which includes a piston, a body in which is formed a chamber, at least a first cylinder which is located in the chamber and which, on an inner side, forms at least part of a sleeve for the piston, and a valve, for controlling movement of the piston, which is located on an outer side of the first cylinder. A stop structure integrally attached to the first cylinder prevents the valve from being removed.

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

Abstract: 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: The hydraulic reciprocating mechanism has a housing and a piston located reciprocably in the housing. The piston and housing define a supply chamber and a return chamber. The return chamber has valve seats at either end. There is an inlet to the supply chamber for pressurized hydraulic fluid and an exhaust outlet from the return chamber. An interconnecting passage extends between the supply chamber and the return chamber. A single popper valve is located reciprocably in the return chamber and is moved by hydraulic forces between positions in which it seats on the respective valve seats. In one position of the popper valve it closes the exhaust outlet and opens the interconnecting passage to admit hydraulic fluid from the supply chamber to the return chamber. This has the result hydraulic fluid in the return chamber drives the piston in one direction.

Abstract: A liquid pump is disclosed having a center block containing inlets and outlets for liquid to be pumped and air to operate the pump with associated valves for liquid and air. A pair of opposed cylinders are provided on opposite sides of the center block and each containing a collapsible bellows connected to a sleeve forming a piston with the liquid being pumped in the chamber within the bellows. Push rodes extend from one piston to the other so that the piston pumping liquid out pushes the other piston to fill with liquid. The bellows have conbolutions of selectively varying wall thickness, and tapered single or dual compression seals are provided where the bellows are joined to the center block. An inflow conical valve and an outflow shuttle valve are provided for each cylinder, and vent tubes are provided to cool the bellows and to actuate the air valve at the end of the piston stroke. An encapsulated sheet member is provided in each cylinder.

Abstract: A control system for a hydraulic percussion mechanism (6) is based on the continuous measurement of the striking rate (z) of the striking piston, or on the continuous measurement of the striking rate (z) of the striking piston together with the quantity per unit time (Q.sub.e) of the hydraulic driving medium coming into the percussion mechanism (6). One, or possibly both, of these parameters is measured from outside the percussion mechanism itself. The control system is configured in such a way that the internal resistance of the percussion mechanism or the hydraulic pump which powers it is increased if there is an increase in the striking rate (z) or the ratio z/Q of the striking rate to the incoming stream rate beyond respective limit values.

Abstract: A hydraulically operated striking mechanism includes a contact pressure control member held at least temporarily in contact with an insertion end of a drilling tool by a mechanism which applies a restoring force in the striking direction. A control conduit is connected by way of the contact pressure control member either to a pressure conduit or to a pressure return conduit. The control conduit actuates a switching element so that a control unit which alternatingly switches the movement of the striking piston performs a reversal movement into an operating stroke position at an earlier or later point in time during the return stroke of the striking piston and thus actuates the operating stroke of the striking piston in the striking direction.

Abstract: Hydraulic hammers are normally controlled by an actuating valve which controls the flow of fluid from a source of pressurized fluid to the hydraulic hammer. During certain periods of operation, the actuating valve totally blocks communication of fluid to the hydraulic hammer, thereby causing the fluid from the source of pressurized fluid to be expelled through a relief valve. The subject hydraulic hammer and control arrangement therefor includes an accumulator for storing the pressurized fluid from the source of pressurized fluid during periods of fluid blockage by the actuating valve and for supplementing the flow of fluid from the source of pressurized fluid when the actuating valve is communicating pressurized fluid to the hydraulic hammer. This increases the overall efficiency thereof.

Abstract: The invention relates to a hydraulic striking mechanism including a cylinder, a percussion piston guided therein and a piston return device which is supported on the percussion piston and is displaceable independently thereof and can be connected on its side facing the percussion piston tip alternatingly to a pressure source or a pressure-free return conduit. The piston return device is configured as an annular piston which is freely displaceable along the percussion piston and the cylinder and forms therewith a piston chamber. The percussion piston has an abutment face at its end remote from the percussion piston tip which cooperates with the annular piston for moving percussion piston in the return stoke direction. The percussion piston, together with the cylinder, defines an oil chamber which axially follows the piston chamber in a spaced relationship. The percussion piston is provided with a cylindrical shoulder within the oil chamber which determines its end position during the return stroke.

Abstract: A variable frequency control for a hydraulic percussion actuator includes a piston bore and a valve bore. A piston is axially disposed within the piston bore, while a valve is axially disposed within the valve bore. A first piston biasing member biases the piston in a first direction while a second piston biasing member, which overcomes the bias of the first piston biasing member to move the piston in a second direction. A first valve biasing pin biases the valve in a third direction while a second valve biasing pin overcomes the bias of the first valve biasing pin to move the valve in a fourth direction. A hydraulic valve actuator displaces the second valve biasing pin when the piston is extended in the second direction, and a piston actuator activates the second piston biasing pin when the valve is extended in the fourth direction. A valve response member controls the time required for the valve to be displaced in said fourth direction upon actuation of said valve actuating member.

Abstract: A variable frequency control for a hydraulic percussion actuator includes a piston bore and a valve bore. A piston is axially disposed within the piston bore, while a valve is axially disposed within the valve bore. A first piston biasing member biases the piston in a first direction while a second piston biasing member, which overcomes the bias of the first piston biasing member to move the piston in a second direction. A first valve biasing pin biases the valve in a third direction while a second valve biasing pin overcomes the bias of the first valve biasing pin to move the valve in a fourth direction. A hydraulic valve actuator displaces the second valve biasing pin when the piston is extended in the second direction, and a piston actuator activates the second piston biasing pin when the valve is extended in the fourth direction. A valve response member controls the time required for the valve to be displaced in said fourth direction upon actuation of said valve actuating member.

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 impact device that consists of a housing having a bore, a piston, and a change-over valve for control of the reciprocal movement of the piston is presented in the present invention. In the present invention, it is not necessary to employ a long-size piston and a high piston speed is obtained and, further, a compact device in which the fluctruation of the pressure in the low pressure path is small can be obtained.

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: Hydraulic fluid pressure moves a piston (22) against a body of incompressible fluid (14), compressing a spring (42). The pressure is released, and the force of the stored energy in the spring (42) is transmitted to the piston (22) by the body of fluid (14) and drives the piston (22) through its power stroke. The fluid (14) is vented to an outlet (8) before the piston (22) reaches the end of its power stroke, removing the force from the piston (22) and allowing it to free travel through the remainder of the stroke. When the motor (2) is operating and the load is removed from the piston (22), the hydraulic fluid inlet (10) is short-circuited to the outlet (8) and the motor (2) automatically shuts off.

Abstract: A hydraulic percussion machine, comprising a body carrying hydraulic passages and valves, and having a gas-filled, hydraulic pressure accumulator for storing the stroke energy which accelerates a piston to strike against a tool. The percussion machine has a separate hydraulic stroke standardizing circuit by action of which the piston stroke is independent of the liquid pressure in the high pressure line supplying the machine and of the volumetric flow.

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 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: An improved impact tool which has a cylinder, a liner mounted therein, a piston mounted in the liner and reciprocated by gas and hydraulic pressure, and a tubular valve slidably mounted on the liner for controlling a hydraulic circuit. The tubular valve is hydraulically pushed up and down without a spring being used. No gas accumulator is used. Thus, the impact tool has a simple construction and is durable.

Abstract: A hydraulic hammer wherein the reciprocal motion of a drill-striking piston is operated by means of a spool valve for switching hydraulic pressure to a double-acting cylinder depending upon the position of the piston. The hydraulic hammer further includes a self starter means which assures activation of the hammer whenever hydraulic pressure is applied to the hydraulic hammer and a means for compensating for variations in boring conditions such that energy is efficiently delivered by the drill striking piston.

Abstract: A reciprocating hydraulic motor, for example for a rotary percussive drilling head, includes a piston and cylinder having a piston face exposed to the pressure in a compression chamber which is connected through ports controlled by the piston to a supply pressure at one end portion of its stroke, and to exhaust at an opposite end portion of the stroke, while between these end portions of the stroke is a compression/expansion travel during which the compression chamber is closed and the liquid in it alternately expands over a higher range of pressure and is compressed over a lower range of pressure.For returning the piston, in the direction in which liquid is compressed, one of two opposed faces of the piston is exposed to the pressure in a biasing chamber which communicates permanently with a constant pressure supply while the other communicates with the compression chamber.

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: An impact tool. A piston movable in a cylinder is pushed up by hydraulic pressure, compressing a gas in a chamber over the piston. The compressed gas drives down the piston by its repulsive force to strike a tool such as a chisel. A valve body in a valve chest in a valve box attached to the cylinder is also reciprocated up and down by hydraulic pressure to communicate an oil supply port for hydraulic pressure to act on alternately the piston and the valve body.

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 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-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: 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: A fluid operated tool is provided which is operable particularly for purposes of causing the linear movement of a tool member in at least one direction. The tool includes a main body, a trigger, an On-Off valve spool, a main piston, a reversing assembly, an accumulator and means for attaching the tool member to the tool. The main body is provided with a plurality of bores in which the On-Off valve spool, the main piston, the reversing assembly, and the accumulator are respectively positioned, and a plurality of channels which function to interconnect the bores. The On-Off valve spool is supported in one of the bores in such a manner as to be operatively connected to the trigger whereby the valve spool moves between first and second positions in response to the actuation of the trigger thereby to selectively open and close various ones of the channels formed in the main body.

Abstract: Hydraulically driven percussion device, comprising a piston reciprocally movable within a body and striking against a tool, said piston defining with reference to the body two cylinder spaces, one of which continuously communicates with the high pressure duct and the other by the aid of a distribution means alternatingly connectable to the high pressure duct and the low pressure duct. At both ends of the piston there are breathing chambers opening into the free atmosphere. Within one of said two cylinder spaces a sleeve-like distribution means has been placed to encircle the piston and which distribution means, in order to move into a position such that movement of the piston directed towards the tool becomes possible, is controlled by means of grooves provided in the piston and in the body when the piston is in its end position farthest removed from the tool and only on condition that the pressure in the high pressure duct exceeds a pressure set with an adjustable valve incorporated in the body.