Patent ID: 6257850
Filing Date: 2001-07-10
Classification: F04B

Abstract:
A seal assembly for a piston which reciprocates within a cylindrical pump barrel, comprising:(a) one or more hydraulic seal rings each having a leading edge which has at least radially inward flares;(b) a cylindrical sleeve forming a seal annulus between said sleeve and the barrel onto which a stack of the one or more seal rings is fitted, the sleeve having a cylindrical portion with one or more circumferential and axially spaced grooves;(c) leading and trailing retaining rings spaced axially on the sleeve, the seal ring stack residing therebetween, the height of which is less than the spacing between the leading and trailing retaining rings so as to form a gap and enable axial movement of the stack of one or more seal rings between the retaining rings so that, at a first position, the stack bears against the trailing retaining ring and the inward flares of the seal ring engaging the sleeve's cylindrical portion for forming an effective annular seal, and conversely, at a second position, the stack bears against the leading retaining ring and each inward flare engages a corresponding circumferential groove formed in the sleeve so as to lessen the radial compression on the one or more seal rings.