An analysis is presented for reciprocating sliding seals and pumping rings with an arbitrary clearance between the seal and rod and preload caused by axial tightening of the gland follower. The analysis is implemented by a fourth-order Runge-Kutta technique applied to the fluid equations in combination with a simple plane strain finite-element calculation for the seal. Results are presented for a variety of pressure differentials and preloads for both outstroke and instroke and both for soft elastomers and hard-filled PTFE material. Preload and initial clearance are shown to play an important role in seal and pumping-ring performance.Presented at the 38th Annual Meeting in Houston, Texas, April 24–28, 1983