Patent ID: 7314353

Claim:
A shaft assembly comprising: a shaft having first and second ends and arranged for rotation about an axis of rotation; a first bearing arrangement engaging the first end of the rotating shaft; a second bearing arrangement axially spaced from the first bearing arrangement and engaging a middle length portion of the shaft; a circular cam member axially spaced from the first bearing arrangement and eccentrically secured axially along the middle length portion of the shaft and arranged to rotate about the shaft axis; a lock member axially spaced from the first bearing arrangement and engaging the middle length portion of the shaft and, in combination with the circular cam member, providing a preload to the first and second bearing arrangements; a piston pump including a cylinder body with a biased piston drivingly displaceable within the cylinder body and continuously engageable with the cam such that rotation of the cam corresponds to reciprocating movement of the piston within the cylinder body; a first valve connected to the piston pump and operable to permit the pumping of fluid into the cylinder body; and a second valve connected to the piston pump and operable to permit the pumping of fluid from the cylinder body of the piston pump.