A reciprocating pump comprising a cylinder and a plunger reciprocable in the cylinder, a member at one end of the cylinder having an axial passage in which the plunger is axially slidable, and a seal between the member and the plunger. The pump is characterized in having a sleeve for protecting the seal...http://www.google.com/patents/US4976192?utm_source=gb-gplus-sharePatent US4976192 - Reciprocating pump
