Abstract: A thread seal comprises a helical rib (6) for use with a threaded member (1). The end portions (7) of the rib (6) are axially staggered and are joined by a transverse thread bridging member (8) which engages a crest (9) of the thread between successive turns of the groove (2). The rib (6) has a tapering cross-section to project radially into the groove (2) and to form a lip seal over a limited axial width of the groove (2) throughout the greater part of the circumferential length of the rib (6). The end portions (7) together with the bridging member (8) are shaped to form a seal over the full axial width of the thread profile. By limiting the area of contact between the rib (6) and groove (2) over the greater part of the circumferential length of the rib (6) the frictional force between them is reduced.

Abstract: A sealing ring (10) includes a plurality of circumferentially spaced axially directed projections (20) on one radial face thereof. In use, the sealing ring is located within a seating groove which is wider than the spacing between the radial faces a (11,12) of the sealing ring, the projections (20) holding the ring against axial movement within the groove while allowing the ring to swell in the axial direction in between the projections so as to maintain the dimensional stability of the outer face (14) of the ring. The sealing ring is particularly useful in uni-directionally operative hydraulic dampers and door closers incorporating such dampers.

Abstract: A fluid-pressure-operable device 1 includes two relatively-movable components 2, 3 defining a variable-volume working chamber 9. A sealing element 5 of elastomeric material is carried, or formed, by one of the components and is in sliding and sealing engagement with the other of the components normally to resist escape of fluid under pressure from chamber 9 to the exterior thereof. That face 15 of element 5 remote from the chamber is so provided with channel 16 that as pressure in the chamber increases the element is permitted progressively to deform and some of the material of the element thus displaced is then accommodated by the channel. When the pressure exceeds a predetermined value, deformation of the element is such that sealing engagement of the element with the other of said components is broken so that the pressure in chamber 9 is relieved to the exterior thereof.