Abstract: An oil well subsurface pump comprising a plunger reciprocally disposed within a working barrel and having check valve means carried thereby. Piston rings are provided on the outer periphery of the plunger for engaging the inner periphery of the working barrel during reciprocation of the plunger which preclude bypassing of the plunger by the well fluid and permit an efficient pumping action upon each stroke of the pump without slippage.

Abstract: An oil well subsurface pump comprising a plunger reciprocally disposed within a working barrel and having check valve means carried thereby, metallic ring means provided on the outer periphery of the plunger for engaging the inner periphery of the working barrel, resilient sleeve or cup means disposed around the outer periphery of the plunger and having one end in engagement with the ring means, means threadedly secured to the outer periphery of the plunger for engaging the opposite end of the resilient means for applying selected longitudinal pressure thereon for radial expansion thereof into engagement with the inner periphery of the working barrel.