Patent ID: 7021911

Claim:
A pump comprising: a sleeve having a wall defining, a cylinder bore and a reciprocating axis extending through the cylinder bore from a first to a second axial end of the sleeve, an inlet extending along the reciprocating axis from the first axial end of the sleeve in fluid communication with the piston bore, and an outlet passing through wall and in fluid communication with the cylinder bore between the first and second axial ends of the sleeve; a piston in the cylinder bore for sliding motion along the reciprocating axis, and having an exposed end thereof extending from the second end of the sleeve adapted for connection to a drive mechanism; an inlet check valve assembly disposed in the inlet; an outlet check valve assembly disposed in the outlet; a pump housing having a cavity for receiving the sleeve; and a pump drive apparatus attached to the pump housing and including a rotating eccentric operatively connected to the exposed end of the piston for imparting reciprocating motion to the piston within the cylinder bore, wherein the pump drive apparatus includes a stub shaft journalled in the housing, and including the rotating eccentric, the stub shaft further including a driven end thereof adapted for operative connection to a rotating drive shaft; a needle bearing disposed between the rotating eccentric and the exposed end of the piston; a pair of thrust bearings disposed on the stub shaft and abutting the needle bearing at opposite axial ends thereof; a pair of rotating bearings disposed between the stub shaft and the pump housing abutting the thrust bearings on opposite sides of the rotating eccentric for supporting the pump drive apparatus in the housing; a retainer element abutting one of the rotating bearings and connected to the housing for limiting axial movement of the stub shaft in the housing; and a thrust washer disposed between the housing and the rotating bearing at the end of the stub shaft opposite the drive end for loading the pump drive apparatus against the retainer element.