Abstract: A strain wave drive includes: an elliptical wave generator shaft rotatable about an axis (X); a flexible flex spline mounted around the wave generator shaft; a ring gear assembly mounted around the flex spline, the ring gear assembly comprising an output ring gear having a circular inner periphery and being sandwiched between two earth ring gears each having a circular inner periphery. The flex spline has a first set of a first number of radially outwardly extending teeth around its outer periphery. Each earth ring gear has the first number of radially inwardly extending teeth to engage with the first set of teeth of the flex spline. The flex spline has a second set of the first number of radially outwardly extending teeth around its outer periphery wherein the output ring gear has a second number of radially inwardly extending teeth.

Abstract: A servovalve includes a fluid transfer valve assembly comprising a primary fluid supply port and a control port, a moveable valve spool arranged to regulate flow of fluid through a first fluid pathway from the primary fluid supply port to the control port, and a jet pipe assembly configured to axially move the spool relative to the fluid transfer valve assembly in response to a control signal to regulate the fluid flow along the first fluid pathway. The jet pipe assembly comprises a steerable nozzle from which fluid is directed to the ends of the spool in an amount determined by the control signal. The spool comprises an opening and an interior passage fluidly coupling the opening to the jet pipe assembly via a second fluid pathway. The first fluid pathway is fluidly isolated from the second fluid pathway within the spool.

Abstract: A flex spline for a strain wave drive. The flex spline includes: a flexible tubular body having a first open end and a second open end; a first set of radially outwardly extending teeth around its outer periphery at the first open end; a second set of radially outwardly extending teeth around its outer periphery at the second open end; and a third set of radially inwardly outwardly teeth located axially between the first and the second sets of teeth. The body also includes one or more sections of changed geometry located between the first and second sets of teeth and/or the second and third sets of teeth, the sections of changed geometry being provided with a geometric feature in the flex spline body that is not present in the remainder of the flex spline body.

Abstract: A strain wave drive includes an elliptical wave generator shaft rotatable about an axis (X), a flexible flex spline mounted around the wave generator shaft and a ring gear assembly mounted around the flex spline. The ring gear assembly includes an output ring gear having a circular inner periphery and is sandwiched between two earth ring gears each having a circular inner periphery. The flex spline has a first number of radially outwardly extending teeth around its outer periphery and each earth ring gear has the first number of radially inwardly extending teeth to engage with the teeth of the flex spline.

Abstract: A strain wave drive includes an elliptical wave generator shaft rotatable about an axis (X), a flexible tubular flex spline mounted around the wave generator shaft and a ring gear assembly mounted around the flex spline. The ring gear assembly includes an output ring gear having a circular inner periphery and is sandwiched between two earth ring gears each having a circular inner periphery. The flex spline has a first number of radially outwardly extending teeth around its outer periphery; and wherein each earth ring gear has the first number of radially inwardly extending teeth to engage with the teeth of the flex spline; and wherein the output ring gear has a second number of radially inwardly extending teeth, wherein the second number is greater than the first number.

Abstract: An integral flapper and nozzle structure for a servo valve assembly whereby the flapper, orifices and nozzles are formed by sheets of metal formed into a single component.

Abstract: An integral flapper and nozzle structure for a servo valve assembly whereby the flapper, orifices and nozzles are formed by sheets of metal formed into a single component.

Abstract: A filter having a hollow body extending longitudinally between a first end and a second end and comprising a plurality of holes formed through said body, and a first compliant section formed in said body, said compliant section comprising a plurality of slits which extend through said body and in a circumferential direction around said filter. A nozzle/filter assembly is also described as well as a method for making the same.

Abstract: The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

Abstract: A nozzle of or for a servo valve comprises a nozzle element having a fluid outlet at a first axial end and a tubular body extending from the first end to an opposed, second axial end. The nozzle further comprises a plug element mounted in and closing the second axial end of the tubular body, thereby defining an internal cavity within the tubular body. One or more openings are formed through the tubular body to fluidly communicate with the internal cavity. A filter may be mounted across the internal cavity at a position axially intermediate the openings and the fluid outlet.

Abstract: A transmission shaft comprising: an input side for inputting torque; an output side for outputting torque; a rod extending in a longitudinal direction between the input side and the output side to transfer torque along the transmission shaft, the rod comprising a first end provided at the input side, a second end provided at the output side and a torsional compliant section extending therebetween providing the transmission shaft with a torsional stiffness. A casing extends around the torsional compliant section and is arranged to resist deflection of the rod without increasing the torsional stiffness of the transmission shaft.

Abstract: An electrical assembly comprises a wall having an opening, one or more electrical leads extending through the wall opening and a grommet arranged in the wall opening. The grommet comprises a body of resilient elastomeric material having at least one hole extending axially therethrough for receiving a respective individual electrical lead. The grommet body has a portion with an external diameter Db which, in an uncompressed state of the grommet is greater than the internal diameter (Dop) of the wall opening whereby when the grommet inserted in the wall opening, the grommet body is compressed into sealing and clamping engagement with the electrical lead.

Abstract: There is provided a method of assembling a torque motor. The method comprises fastening the torque motor to a support such that any magnetic elements of the torque motor are substantially fixed in position with respect to the support, but without securing an armature to the torque motor, locating the armature of the torque motor around a fixed element of the torque motor such that the armature is able to move with respect to the fixed element, moving the armature with respect to the fixed element whilst the magnetic elements of the torque motor are substantially fixed in position with respect to the support, so as to position the armature in an in use orientation or position, and then attaching the armature to the fixed element in the in use orientation or position.

Abstract: The disclosure provides a method of securing a feedback spring relative to a spool of a servovalve, the method comprising inserting the feedback spring at least partially into an internal cavity of the spool, inserting two fixing members into the internal cavity such that they each oppose a portion of the feedback spring, bringing the fixing members into respective set positions, such that the fixing members clamp the feedback spring and prevent relative movement between the feedback spring and the spool, and securing the fixing members in their respective set positions, such that the fixing members remain in their clamping positions and prevent relative movement between the feedback spring and the spool.

Abstract: The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

Abstract: A valve assembly includes a valve housing having a bore formed therein. The bore has an axis A and comprises a circumferentially extending groove formed at an end portion. An axially outer wall of the groove includes at least two circumferentially spaced radially inwardly extending retaining elements defining an axial slot therebetween. An end cap is received in the end portion of the bore and closes the end of the bore. The end cap includes a retaining portion that includes at least one radially outwardly extending retaining element which is shaped to be insertable through the axial slot into the groove and rotatable therein to a retaining position in which the radially outwardly extending retaining element aligns with one of the radially inwardly extending retaining elements to prevent axial withdrawal of the end cap from the bore.

Abstract: A torque motor for a servovalve is provided, the torque motor comprising an armature and a first pole piece. The first pole piece has a first portion and a second portion that is selectively moveable relative to the first portion such that a size of an air gap formed between the second portion and the armature is adjusted in response to the movement of the second portion relative to the first portion.

Abstract: A valve body for a servovalve is provided, the valve body comprising: a first surface; a second surface offset from the first surface; a first passage extending through the body between the first and second surfaces from a first side of the body to a second side thereof; a second passage extending from the first surface towards the second surface and intersecting the first passage; a supply port joined with the first passage; a control port joined with the first passage; a return port joined with the first passage, wherein the return port comprises a third passage extending through the body between the first and second surfaces from a third side of the body to a fourth side thereof and intersecting with the first passage.

Abstract: A coupling for allowing torque transmission between a first and second shaft, the coupling comprising: a cup-shaped portion provided at a first end of said first shaft and a first end of said second shaft being positioned within said cup-shaped portion; and said coupling further comprising a biasing means positioned between said first and second shafts, such that said biasing means is in contact with both of said first and second shafts. A shaft system can include the first coupling in combination with a third shaft and a second coupling that is provided between the third shaft and either a second end of said first shaft or a second end of said second shaft. The second coupling is identical to the first coupling.

Abstract: An electromagnetic device is disclosed, the electromagnetic device comprising a core support having an exterior surface comprising at least one radial protrusion, a tubular magnetic core positioned around a portion of the length of the core support, the tubular magnetic core having an interior surface, at least one indent located in the interior surface of the tubular magnetic core, wherein the at least one protrusion is located within the at least one indent to prevent relative longitudinal movement between the core support and tubular magnetic core, and a primary coil and at least one secondary coil, each coil positioned around a portion of a length of the tubular magnetic core.