A method and apparatus for attaching sutures to curved surgical needles. A vibratory bowl and vibratory rail function to present individual surgical needles to a transfer system in a predetermined orientation. The transfer system then delivers each oriented needle to a frame which positions the needle for subsequent swaging by a rotating die system which selectively impacts the needle to secure the suture thereto.

A process for manufacturing surgical needles from solid, cylindrical needle blanks. A plurality of needle blanks are cut from a roll of wire and mounted to a flat carrier strip. The carrier strip then indexes each needle blank to a grinding station where an orbital grinding means grinds the distal end of each needle blank into a taper point while the needle blanks are held fixed in the carrier strip.

There is disclosed an apparatus and a method for progressively forming high strength surgical needles from bulk needle stock material. The apparatus generally includes a series of progressive needle processing stations. A first series of needle processing stations removes material from needle stock material to rough form needle blanks attached to a carrier strip while a second series of processing stations refine the rough formed needle blanks attached to the strip into the desired surgical needles. The disclosed method generally includes the steps of gutting needle stock material to rough form needle blanks attached to a carrier strip and progressively coining the rough formed blanks into surgical needles. Finally, there is disclosed a high bend strength surgical needle formed on the disclosed apparatus or by the disclosed method. Preferably, the surgical needle is a surgical incision member having a predetermined radius of curvature and an optimized conical radius at the tips.

A taper point surgical needle having improved needle point strength is disclosed. In one embodiment of the needle, a tip portion includes first and second integral tapered regions having first and second cross-sectional areas respectively which decrease progressively toward the tip of the needle in accordance with first and second angles of inclination respectively, with the first angle being greater than the second angle. In another embodiment of the needle of the present invention, the tip portion includes a third tapered region integral with the second tapered region and having a cross-sectional area which decreases progressively toward the needle tip in accordance with a third angle of inclination which is smaller than the second angle.

A surgical needle has a top edge formed by two pressed faces located inside or outside of curvature from pressing a material blank made of austenitic stainless steel having fibrous texture and cutting edges formed on both sides of a base. The top edge is sharp at a needle point and the sharp needle point is constituted of fibrous texture formed at the surface layer of the material blank. Grinding marks extending crosswise formed on the face of the mold are transferred to the pressed faces. A mold constitutes plural faces forming projecting angles (angle between two intersecting faces is 180° or below, and the line at which the two faces intersect is made as a projecting line) along edges of the blocks made of two rectangular prisms, and constitutes a cavity by suitably contacting the edges of the blocks.

A process for progressively manufacturing cutting edge needles or wire members. Needle blanks or wire blanks are cut from a roll of wire and mounted to a carrier strip. The carrier strip and needles are moved through a succession of coining dies and at least one trimming die, wherein the first coining die is an open coining die and the one or more successive coining dies are closed coining dies. The needle blanks or wire members are optionally curved, heat treated and electrochemically treated resulting in cutting edge needles or wire members formed without a grinding step and without adversely affecting point ductility.

A continuous process for heat treating and cleaning and tempering martensitic stainless steel surgical needles is disclosed. The method comprises exposing the surgical needles to a partial vacuum at a temperature less than the heat treating temperature to remove volatile surface contaminant. Then the needles are heat treated in an argon gas environment at a pressure equal to or greater than 1.0 Torr. Next the temperature of the oven is lowered to temper the needles.

The present invention provides a surgical needle having a needle tip end and a clamping portion to be clamped by a needle holder for applying a current, wherein the needle tip end is made from a conductive material which is electrically connected to a conductive material of the clamping portion, an insulating layer is provided over the clamping portion and a tip surrounding portion of the surgical needle, whereas at least the needle tip end is electrically exposed, and when the insulating material over the clamping portion is clamped by the needle holder, the conductive material of the clamping portion is electrically connected to the needle holder.

A curved surgical needle and a method for producing the same from a solid sheet of material rather than from coiled wire including the steps of drilling a bore in one edge of the material, grinding an edge opposite the drilled edge to form a sharpened point, curving the material and cutting the material at a point of equal distance between each drilled bored to provide a surgical needle. A suture is then attached to the surgical needle, optionally lubricated, sterilized, and packaged by suitable means known in the art.

Channel-bodied surgical needles and surgical incision members are disclosed having a generally U-shaped cross-sectional body portion and a penetrating tip portion formed on at least one end thereof. Preferably, penetrating tip portions are formed at both ends of the channel-bodied portion. The surgical needle and/or surgical incision member may additionally includes apparatus engagement structure formed adjacent either end of the body portion and engagable with a suitable surgical suturing apparatus. The channel-bodied surgical needle and/or surgical incision member may additionally include securement structure for attachment of a length of suture material thereto. There is also disclosed apparatus for forming a channel-shaped body portion and the suture attachment structure. Additionally, methods for suturing tissue sections, particularly vascular tissue sections, with the channel-bodied surgical needle and the channel-bodied surgical incision members, are disclosed. Also, methods for forming the channel-bodied surgical needle and channel-bodied surgical incision member are disclosed.

A swaging apparatus for attaching sutures to surgical needles includes at least a first die and a second die. The first die has a first member, which includes a first surface, and a second member, which includes a second surface. The second member is movable relative to the first member between an extended position, in which the second surface extends beyond the first surface, and a retracted position, in which the second surface does not extend beyond the first surface. The second die has at least one surface and is movable relative to the first die between a remote position and an adjacent position. When the second die moves relative to the first die from the remote position towards the adjacent position, the second member of the first die is caused to move from the extended position towards the retracted position, and the surfaces of the first and second dies cooperate with one another so as to swage a surgical needle positioned between the first and second dies. The second member of the first die is movable to the retracted position when the second die abuts the first die. In this manner, surgical needles of many different types or sizes can be swaged by the swaging apparatus.

A semi-automated machine and method for singulating individual surgical needles from an bulk supply and attaching a suture to the surgical needle is described. Each of the surgical needles has a suture receiving opening formed therein for receiving a suture. The machine includes a singulation station having a sliding surface that assists an operator in singulating needles and depositing them in a pair of drop locations for subsequent automatic handling. Indexing conveyors, an articulated robot and a precision conveyor are used with a precise positioning station for orienting each needle for automatic handling. A universal gripper mounted on a rotary indexing device automatically receives each individual needle in a predetermined orientation and conveys the needle for sequential processing from station to station to form the needle-suture assembly. A suture feeding and cutting station automatically cuts an indefinite length of suture material to a definite length suture strand and automatically inserts an end of the definite length suture strand into the suture receiving opening formed in the needle. A swage station is provided for swaging the needle to close the suture receiving opening about the suture to secure said suture thereto and form therefrom a needle and suture assembly. A suture pull-test station test each needle suture bond, and selectively and destructively tests the bond for adjusting the swage dies and for statistical quality control. A final off-load station provides an apparatus for assembling a predetermined number of need-suture assemblies in a bundle for subsequent packaging.

A method for manufacturing a surgical needle devoid of a grinding process includes the steps of swaging a needle blank to define a substantially tapered or conical needle end, pressing the tapered needle to form a plurality of intersecting surfaces and forming cutting edges along the lines of intersection of the intersecting sides. The needle may be subjected to an etching process (e.g., an acid bath) to sharpen the cutting edges and/or provide a matte finish on the needle. The needle produced by the novel process is extremely sharp and durable, and exhibits an enhanced retention of sharpness relative to conventional ground needles over periods of prolonged use.

A process for manufacturing a surgical needle incorporates at least one pressing operation which, preferably, in conjunction with a trimming and/or etching process, ultimately forms the sharpened needle end. The grinding operation in the preferred process does not produce the primary sharpened edges of the needle, but, rather is incorporated, in one instance, to reduce excess needle material prior to the pressing operation. Consequently, the amount of flash material generated during pressing is substantially reduced. This feature desirably enhances the subsequent trimming and etching operations, and produces a needle which is extremely sharp, durable and exhibits an improved retention of sharpness over periods of prolonged use.

Surgical needles are produced by immersing a needle possessing a distal end surrounded at least in part by flash material and a body portion in an acid bath according to a predetermined sequence, wherein the distal end of the needle is exposed to the acid bath under conditions sufficient to remove flash material from the distal end of the needle and the body portion of the needle is exposed to the acid bath under conditions sufficient to provide a matte finish on at least a portion of the body portion of the needle.

A process for manufacturing a surgical needle incorporates at least one pressing operation which, preferably, in conjunction with a trimming and/or etching process, ultimately forms the sharpened needle end. The grinding operation in the preferred process does not produce the primary sharpened edges of the needle, but, rather is incorporated, in one instance, to reduce excess needle material prior to the pressing operation. Consequently, the amount of flash material generated during pressing is substantially reduced. This feature desirably enhances the subsequent trimming and etching operations, and produces a needle which is extremely sharp, durable and exhibits an improved retention of sharpness over periods of prolonged use.

A method of mechanically treating alloy metal surgical needles to improve bending strength is disclosed. The needles are curved and reverse-curved in this method to improve bending strength.

In a method of attaching a suture to a needle barrel, a first compression stroke compresses the radially-defined top of the barrel against a suture in the bore of the barrel while restraining the bottom and sides of the barrel against deformation. A second compression stroke compresses the bottom of the barrel against the suture while restraining the sides against deformation. In another method, the top and bottom are compressed concurrently while the sides are restrained against deformation. An apparatus for attaching a suture to a needle barrel includes two die sets, each including a die with a groove therein. In one die set, the groove protects the bottom and sides of the barrel from deformation while the top is compressed. In the other die set, the groove protects the sides of the barrel from deformation while the bottom is compressed.

A method of stress relieving drilled surgical needles is disclosed. At least the metal about a drilled bore hole is heat treated to relieve stress without annealing.

A liquid flow rate control valve is provided in which since a total area of overlapping sections of a communication hole group (38c, 38d) of a distributor (38) and an outlet opening (37a, 37b) of a sleeve (37) changes when the distributor (38) is rotated by a first electric motor (46), if a rotor (42) is rotated by means of a second electric motor (47), an input port (31e) communicates with an output port (31f) through an inlet opening (42c, 42d) of the rotor (42), the communication hole group (38c, 38d) of the distributor (38), and the outlet opening (37a, 37b) of the sleeve (37) when the inlet opening (42c, 42d) of the rotor (42) passes through the overlapping sections, thereby making it possible to carry out PWM control of a flow rate of liquid. Since a thrust load in an axis (L) direction does not act on the distributor (38) and the rotor (42), supporting the distributor (38) and the rotor (42) becomes easy, thereby enabling the cost and weight to be cut.

Method of indicating the position of a hydraulically actuated armature, comprising an adjust cylinder for actuating the armature, connected by at least one pressure medium line to an adjustment valve through which the pressure medium line can be switched between pressure-causing forward flow and pressure-less backward flow, wherein the flow through the pressure medium line is converted into a number of electric pulses and the number of pulses reflecting the flow is processed in a program in an indicator unit such that the number of pulses occurring in a predetermined adjustment travel when the flow in the pressure medium line is pressure-less is calculated as being the same adjustment travel as when the pressure medium line is switched to be the pressure line.

The invention relates to a neutral setting apparatus for adjustable hydraulic machines, in particular the adjustment of the neutral position of a servo valve. In particular, the invention relates to servo adjustment devices with mechanically adjustable control pistons, wherein the forces necessary for this can be applied mechanically, electro-magnetically, pneumatically or hydraulically. The invention relates to a neutral setting apparatus of an adjustable hydraulic machine, with a housing in which a mounted input shaft is arranged, to one end of which a torque can be applied for rotating the input shaft about an axis. Thus providing a robust and cost-effective setting mechanism for the neutral position of a servo valve.

In a stroke-limiter equipped integral power steering apparatus, a valve body of a spring-loaded-plunger-equipped limiter valve is configured to enable a position of the valve body relative to a housing to be adjusted in a longitudinal direction of the valve body via an intermediate sleeve.

The present invention relates to devices and systems that alter intracranial compliance, cerebral blood flow and/or intracranial pressure pulsatility/waveform by oscillating the contraction and expansion of a compressible composition within the cranial or spinal cavities such that they increase intracranial capacity. The contraction and expansion of the compressible composition in the oscillating compliance devices can be due to an individual's intracranial pressure, the result of the expansion and compression of a reservoir which is mediated by the contractility of the heart or driven by a pump gaited to a biorhythm. The invention also relates to methods for protecting an individual's brain from abnormal arterial pulsations and for altering an individual's cerebral blood flow using the devices and systems of the invention. The oscillating compliance devices can be used to treat several diseases and/or conditions characterized by altered/abnormal intracranial compliance, cerebral blood flow and/or intracranial pressure pulsatility/waveform, including hydrocephalus, stroke, dementia and migraine headaches, vasospasms, congestive heart failure, cardiopulmonary bypass or carotid endarterectomy.

A control valve comprises a first spool 22, a second spool 24 encircling at least part of the first spool 22 and angularly moveable relative thereto, and a sleeve 32 encircling at least part of the second spool 24, the second spool 24 being angularly moveable relative to the sleeve 32, the first and second spools 22, 24 having first and second series of ports 28, 30 registrable with one another, depending upon the relative angular positions of the first and second spools 22, 24, to control communication between at least a pressure line 16, a return line 18 and a control line 50 provided in or connected to the sleeve 32, the second spool 24 and the sleeve 32 having third and fourth series of ports 66, 68, axially spaced from the first and second series of ports 28, 30 and registrable with one another, depending upon the relative angular positions of the second spool 24 and the sleeve 32, to control communication between at least the control line 50 and the return line 18, and latch means 56 operable to resist movement of the second spool 24 relative to the sleeve 32.

The invention relates to an energy-efficient apparatus driven by compressed air and equipped with a dual piston function for tensioning, or clamping, or centering, or punching, or welding, or clinching, for use in body construction in the automotive industry. The apparatus is driven by a pressurized fluid, in particular by compressed air. It is shown how a significant amount of operating costs can be saved while, at the same time, conserving the environment and consuming a low amount of pressurized fluid, in particular compressed air. In addition, the pivoting angle of a toggle joint assembly and thus of an apparatus connected thereto, for example, a tensioning arm of a toggle tensioning apparatus, can be continuously adjusted in both directions while, at the same time, adjusting a sampling device using sensors, for example, microswitches, or inductive switches, or pneumatic switches, or limit switches.

An energy-saving valve includes a spool-driving unit which changes the position of a spool to a position at which compressed air is discharged from a first output port without pressure control and includes a pressure control unit which changes the position of the spool to a position at which compressed air is discharged from a second output port in a predetermined pressure level due to pressure control. The pressure control unit includes a pressure control piston, a pressure-receiving surface which enables air pressure in the second output port to act on the pressure control piston, a cylinder chamber, a pressure control channel, and an elastic member which applies biasing force to the pressure control piston in a direction opposite to the action of air pressure on the pressure-receiving surface to determine pressure.

A manual release valve is provided for a electro-hydraulic actuator of the type including a piston movable in a cylinder and defining a piston side chamber and a rod side chamber, the valve threadedly attached to the housing of the actuator and extending at least partially within the fluid housing conduits, the valve moveable from a closed position fully seated in the housing to an open position for fluidly connecting both the piston side chamber and the rod side chamber to the reservoir, the valve further including a pressure relief portion that is operable when the valve is in the closed position for relieving pressure from at least one of the piston side chamber or the rod side chamber.

A radial thermal engine with an improved valve system is disclosed herein comprising intake and exhaust port valve assemblies fluidly connected to respective intake and exhaust ports contained within a cylinder head assembly. Each intake and each exhaust port valve assembly comprises at least one rotatable port cover having spaced apart openings which are periodically alignable to the intake and exhaust ports, respectively.

A cup for an air valve assembly in a positive displacement pneumatic motor includes a cup body, a gas cavity, and a first pilot slot. The cup body is rectilinear and has a sliding face as one side, and the gas cavity is concave and extends into the cup body through the sliding face and terminates within the cup body. The first pilot slot extends from the gas cavity and into the cup body through the sliding face and terminates within the cup body.

Valve control device includes a body with a longitudinal axis, a control member housed at least partially in the body in a bottom portion along the longitudinal axis, a piston movable along the longitudinal axis and housed in a portion of the body forming with the piston a control chamber of the piston, an element movable in rotation with respect to the longitudinal axis on a top portion of the body, and sealing means between the movable element and the control chamber in the area of the connection port and/or of the passage.

A fluid-working machine has a working chamber of cyclically varying volume, high and low pressure manifolds, and high and low pressure valves for regulating the flow of fluid between the working chamber and the high and low pressure manifolds respectively. A controller actively controls at least one said valve to determine the net displacement of working fluid of the working chamber on a cycle by cycle basis. At least one said valve is a variable timing valve and the controller causes the valve to open or close at a time determined taking into account one or more properties of the performance of the fluid working machine measured during an earlier cycle of working chamber volume.

An assembly of valve sections includes an inlet section, an outlet section, a working section, and a working section. The working section is a conventional pressure compensated working section. The working section includes a directional control valve, a pressure compensator valve, and a pressure limiter valve. The valves are of integral construction, such that each is an essential part to complete the other. The pressure compensator valve includes a pressure compensator spool movable between an opened position and a closed position in response to a pressure differential across the spool. The pressure limiter valve includes a pressure limiter spool that moves to an open position to change the pressure differential and close the pressure compensator valve when a selected limit pressure is reached.

An electrical discharge machine with automatically replaceable electrodes. The machine includes an electrode holder with a clamp operable to alternately receive and release an electrode, an electrode cartridge containing a plurality of stacked electrodes and a shuttle movable toward and away from the electrode holder. When the shuttle is moved toward the electrode holder, it removes an electrode from the cartridge and moves it into alignment with the electrode holder.

Graphite and/or carbon surfaces are coated with a titanium nitride coating by exposing the substrate to electric arc thermal spray process wherein titanium wire as the source of titanium and nitrogen is used as the propelling (atomizing) gas.

A ceremonial illuminary including a voltage supply mechanism, a switching mechanism that is electrically connected to the voltage supply mechanism, a first lamp electrically connected to the switching mechanism, a second lamp electrically connected to the switching mechanism wherein the switching mechanism provides voltage to the first lamp to illuminate the first lamp and then switches to provide voltage to the second lamp instead of the first lamp when the first lamp burns-out and no longer illuminates. The first lamp and the second lamp are secured with an enclosure.

The present invention is a serial to parallel data conversion method and device where new serial data are stored within a first n-bit register prior to presentation at an n-bit parallel output. Subsequently, additional data are stored within a second n-bit register while the data stored within the first register are presented at the parallel output. Data storage and data presentation are thereafter alternated, thereby eliminating the problem of setup time seen in prior art.

An analog-to-digital converter can use a variable sampling rate. By using a variable sampling rate analog-to-digital converter and an anti-aliasing filter lower sampling rates, and accordingly, generally lower power consumption may be achieved. For example, a lower sampling rate can be used when it is determined that no undesirable signals are present and a higher sampling period can be used when an undesirable signal is present. Determining the presence of an undesired signal can be based on signal-to-noise ratio, over-sampling, bit error rate, using a detector, etc. An undesirable signal can be any signal that is close in frequency to a signal of interest or a signal farther away in frequency that has a relatively high amplitude. Sampling rate can be varied in a binary fashion, stepwise, continuously, etc.

An analog front-end circuit includes an analog processing circuit, an A/D converter, a target register in which a lower limit target value of an input image signal is set, and a calculation circuit. The analog processing circuit includes an offset control circuit which performs offset control based on an offset control value set in an offset control register. The calculation circuit monitors the A/D-converted value in a lower limit value output period when the A/D-converted value corresponding to a lower limit value of an input range is output from the A/D converter, and sets the offset control value that causes the A/D-converted value to become closer to the lower limit target value set in the target register in the offset control register.

This disclosure relates to a micro manipulator having a simple structure and having high possibility of recording a biological signal of a neuron at a desired position by improving positioning resolution of an electrode disposed adjacent to a subject's brain neuron or an electrode holder attached with the electrode. The micro manipulator according to the disclosure includes: a motor which includes a shaft and a vibration portion; a mobile which is connected to the shaft so as to be movable along the shaft; and a frame which supports the motor, wherein an electrode is connected to the mobile in a direction parallel to a longitudinal direction of the shaft, and wherein when the mobile moves linearly in accordance with a vibration of the shaft due to the vibration portion, the electrode moves linearly.

Apparatuses, methods and systems for lighting fixture determining its power usage and monitoring its operational health are disclosed. One embodiment includes a method of a lighting fixture determining its power usage. The method includes sensing, by an ambient light sensor, an intensity of light emitted from the lighting fixture, and estimating power usage of the lighting fixture based on the sensed intensity of light.

Method and apparatus for tri-axially aligning, folding, trimming and edge stitching a cloth sheet particularly adapted for making pockets for garments.

A sleigh for travel over a snow covered surface adapted to be disassembled or knocked down into a storage or transport position, from an operating position, is shown. Runners of the sleigh are pivotally connected to a floorboard along side edges thereof. The runners are locked into an operating position and may be unlocked to fold against a bottom surface of the floorboard in a stored position. An upper body including a seat is formed of multiple planar pieces which are dependently interlocked with each other for assembly and later disassembly. Means are provided for interlocking the runners to a hitching assembly to which a horse is conventionally harnessed.

A two wheeled, height adjustable cart for pulling farm implements and maintaining a stable height for the cart relative to the field includes a pair of spaced wheels to which main frame members are connected and extend upwardly therefrom. A work platform having a seat for an operator is slidably mounted on the main frame members and selectively movable between an elevated position and a lowermost position, and attached to the work platform is the farm implement which is raised and lowered concomitant with the movement of the work platform from the elevated position to the lowermost position. Foot pedals mounted on the work platform actuate the raising of the work platform to the elevated position and the lowering of the work platform to the lowermost position. In addition, position setting mechanisms mounted on the main frame members allows the operator to set the lowermost position to which the work platform will descend, and which determines the depth the farm implement will extend into the soil, and also allows the operator to raise the work platform and the attached farm implement when both are stationary, or when the cart is stationary for undergoing maintenance.

In a method for correcting a calibration table T(n,k) of a CT apparatus that contains calibration values, the CT apparatus having a detector system with N≧2 rows of detector elements following one another in the z-direction that include a first active row of detector elements in the z-direction and a last active row of detector elements in the z-direction, for correcting the calibration values of the aforementioned first and last active rows of detector elements, a reference vector R(k) is produced, the error is determined with respect to the first and last active rows of detector elements, and the error F(n,k) of the first and last active rows of detector elements is subtracted from the corresponding calibration values of the calibration table T(n,k) for determining corrected calibration values Tcor(n,k) with respect to the first and last active rows of detector elements.

A method and system are presented for enhancing one or more images of an object, so as to increase the visibility within the images of one or more structures within the object. The object may be an anatomical region of a patient, and may include one or more reference structures, for example skeletal structures or vertebral structures, and one or more treatment targets, for example tumors or lesions. An operator, for example a top-hat filter operator, selects at least a first neighborhood and a second neighborhood within the images. The operator selects within each neighborhood one or more pixels having an optimal pixel value, and eliminates the remaining pixels in these neighborhoods. When the operator is applied to the selected neighborhoods, only the pixels having the greatest pixel values remain in the selected neighborhoods, and the remaining pixels are eliminated in the selected neighborhoods. As a result, desired features can be located and enhanced in the images.

In order to achieve seal durability and bring about a damping action for a piston-type pressure regulating valve, a pressure regulating valve of the present invention is characterized by a valve moving member moving in such a manner as to cause communication or block communication between a primary chamber and a secondary chamber within a case, wherein a plurality of central members are arranged between the case and the valve moving member and the plurality of central members are taken to be different materials. It is then possible to bring about both a damping action and seal durability using the central members by providing central members of different materials.

A compressor includes a housing; a compressor liner positioned within the housing and at least partially defining a first cylinder with an inlet and an outlet; a piston positioned within the first cylinder and configured to compress air flowing into the first cylinder through the inlet; a cylinder head at least partially defining the first cylinder; and a sealing assembly for sealing an interface between the compressor liner and the cylinder head. The sealing assembly includes a ring seal at an interface between the cylinder head and the compressor liner; a vent port on an opposite side of the ring seal from the first cylinder; and a vent tube extending between the vent port and the inlet such that air leaking through the ring seal from the first cylinder flows through the vent port, through the vent tube, and into the inlet.

A hydraulic actuator system including an actuator and a valve assembly configured for bi-directional regeneration. The actuator may include a hollow body and a rod disposed within and extending outwardly from the hollow body. The rod may include a first chamber within the rod and a piston disposed at one end of the rod, defining a second chamber and a third chamber within the hollow body. A valve assembly may be in fluid communication with a first conduit, a second conduit, the first chamber, the second chamber, and the third chamber, wherein the valve assembly is configured to selectively couple one of the first conduit and the second conduit to one or more of the first port, the second port, and the third port, wherein one of the first conduit and the second conduit is configured as a pressure source.

A variable displacement fluid working machine includes an inward ring and an outward ring, one of the inward ring and the outward ring including a rotatable ring cam coupled to a drive shaft, the other including a plurality of radially extending piston cylinders circumferentially spaced around the respective ring. The outward ring has first and second axially spaced structural members and a plurality of demountable blocks demountably retainable therebetween, the demountable blocks having either piston cylinders or ring cam segments. The demountable blocks are removable radially to facilitate maintenance and repair and to facilitate radial access to the inward ring.