Oil-controlled piston, and oil control means

Claim 1

A piston, for use in a reciprocating piston machine, comprising: a hollow piston body; said body having an inner, annular wall with oil ring drain hole means formed through said wall; said piston having a reciprocating axis; said body further having passageway means formed therewithin for admitting oil therethrough, substantially along said axis, from an area at one axial end of said piston toward an opposite axial end thereof; said body further having means defining an oil impingement deck intermediate said one and opposite axial ends, said deck being cooperative with said wall to define therewith a trough or reservoir in which, with piston reciprocation, oil admitted via said passageway means becomes temporarily received; said drain hole means comprises at least one plurality of drain holes which open at one end thereof on said trough or reservoir; and independently resiliently held and selectively replaceable spring pin means carried at solely one end thereof by said drain holes for restricting oil admittance into said one end of each drain hole to an area within said trough or reservoir which is spaced-apart from both said deck and said wall, each said spring pin means comprising a resilient hollow tube having a single continuous slot along its entire length.