Abstract: A check valve comprises a valve housing defining a valve opening; and a flapper element. The flapper element has a proximal end, and is pivotally mounted to the valve housing adjacent the periphery of the valve opening at its proximal end for pivotal movement between a closed position, in which it blocks the flow of fluid through the valve opening and a fully open position in which it permits the flow of fluid through the valve opening. At least one spring damping element is located between the flapper element and the valve housing for providing a damping force resisting the pivotal movement of the flapper element towards its open position. The at least one spring damping element being operable to produce a damping force only over a final range of the pivotal movement of the flapper element as it approaches its fully open position.

Abstract: A servovalve includes: a fluid transfer valve assembly comprising a supply port and a control port; a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal; and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The drive assembly comprises a piezoelectric actuator configured to vary the flow of fluid to respective ends of the valve spool in response to the control signal.

Abstract: A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port; a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal; and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The drive assembly comprises a steerable jet pipe moveable by an amount determined by the control signal to cause corresponding movement of the valve spool and the jet pipe terminates at one end in a nozzle and at the other end being in fluid flow engagement with a fluid supply pipe. Movement of the valve spool is caused by fluid flowing from the nozzle to engage with the valve spool.

Abstract: An apparatus for converting rotational movement into linear movement is disclosed. The apparatus comprises: a screw member having a threaded external surface and a sleeve member having a threaded interior surface for receiving the threaded external surface of the screw member, wherein the threaded surfaces are configured so that rotation of the screw member relative to the sleeve member, in use, causes the screw member to move axially relative to the sleeve member. The apparatus may also comprise a force applicator for applying pressure to the region between the screw member and sleeve member so as to urge the external surface of the screw member and the opposing interior surface of the sleeve member apart from each other.

Abstract: A damping valve for a hydraulic damper comprises a valve housing comprising an inlet chamber and an outlet chamber. A valve seat is arranged between the inlet chamber and the outlet chamber. A valve element having a cylindrical first portion is slidably received in a cylindrical bore of the valve housing. A second portion of the valve element has a valve surface for selectively engaging and disengaging the valve seat to allow passage of hydraulic fluid between the inlet chamber and the outlet chamber. A spring element is mounted within the valve housing for biasing the valve element into engagement with the valve seat.