Abstract: In a preferred embodiment of hydraulic actuator wherein a piston rod is longitudinally positionable via a tail end of a cylinder, tail-end static and dynamic seal members are of plastic, of relatively elongate trapezoidal section, and a single metal spring axially preloads the two seal members in compression, via the series-related respective ends of the seal members. Engagement with the ends of each seal member are frusto-conical, to substantially match the sloped ends of the trapezoidal section, and the slope directions of these seal-member engagements are (in the case of the dynamic seal) such as to locally impart radially inwardly directed force, to drive outer ends of the seal into circumferentially uniform engagement with the piston rod of the actuator; in the case of the static seal the slope directions of seal-member engagements are such as to impart radially outwardly directed force, to drive outer ends of the static seal into similar engagement with the bore of the cylinder.

Abstract: An annular elastomeric seal-ring construction having a body adapted for stabilized retention in a circumferential seal-ring groove in one of two relatively rotatable members and for circumferentially continuous resilient contact with an opposed wiping surface of the other member. The resilient wiping contact is established via an integral rib of width less than body width, wherein the locus of the rib undulates axially as a function of azimuth about the axis of the ring body.