Abstract: A hydraulic seal for sealing between two hydraulic components (1, 2) that move axially one within the other comprises a first pressure-energized ring seal (3) located between the components so as to respond to hydraulic pressure on an axially directed inner face of the seal, and a second ring seal (7) located adjacent the inner face of the first seal (3) so as to control the flow of hydraulic fluid to the first seal. The second ring seal (7) is located in an annular groove (8) in one of the components (1) with an outer annular face (11) that is directed axially towards the first seal (3) and lies opposite an adjacent side wall (13) of the groove (8) to be supported thereby. A sealing lip (9) protrudes from the groove (8) and has a radially directed annular sealing face (15) to engage in face-to-face contact with the other of the components (2).

Abstract: A sealing assembly comprises a resilient sealing element (1), possibly substantially T-shaped in cross-section, with a horizontal top portion (2) and a vertical portion (3) depending from the top portion and possessing a rounded sealing lip (4) at an end remote from the top portion (2). The assembly also comprises supporting elements (5) of substantially non-resilient material positioned one on each side of the vertical portion (3) characterized in that the surface of the sealing lip (4) is less rounded than semi-circular when in a non-deflected condition. Opposed sides of the vertical portion (3) meet the surface of the sealing lip (4) at turning points (T, P), and the surface of the sealing lip between these turning points preferably lies within semi-ellipses whose minor radii (B) are from 30% to 80% of the major radii (A) extending between the turning points (T, P).

Abstract: A sealing assembly, suitable for sealing between two relatively-slidable parts, includes a sealing ring which is housed in an annular groove in one of the parts, which is formed with two circumferential lip portions and which is formed with a circumferential landed portion disposed between those portions. Elastomeric energizing means, also in the grooves and in engagement with the sealing ring, urges the lip portions into fluid sealing engagement with the other of the parts. The landed portion is, under conditions of low fluid pressure upon the assembly, free from fluid sealing engagement with the other part but, under conditions of high fluid pressure upon the assembly, is caused to come into fluid sealing engagement with the other part to supplement the sealing by the lip portions and to share with those portions contact stresses arising on relative movement of the two parts under high applied fluid pressure.

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.