Patent ID: 7470117

Claim:
A pump comprising: a pump housing including; a first pumping chamber, a second pumping chamber substantially parallel to the first pumping chamber, a substantially cylindrical bore, located between the first and the second pumping chamber, extending from an outside surface of the housing into the housing, the bore being substantially parallel to the first and the second pumping chamber and having a curved side wall and an end face; a first fluid passageway coupling the first pumping chamber with the bore, the first fluid passageway intersecting the curved sidewall of the bore; a second fluid passageway coupling the second pumping chamber to the bore, the second fluid passageway intersecting the curved sidewall of the bore; a common spill passageway extending coaxially from the end face of the bore into the housing; and a substantially cylindrical selector valve fixedly coupled to the bore, the selector valve including; a curved external surface forming a mating surface with the curved surface of the bore, a through fluid passageway extending from one side of the curved external surface to an opposite side of the curved external surface, the through fluid passageway coupling the first and second fluid passageway and being substantially coaxial with the first and second fluid passageway; a third fluid passageway coupling the through fluid passageway to the common spill passageway, the third fluid passageway being substantially perpendicular to the through fluid passageway; and a ball valve member disposed in the through fluid passageway, the ball valve member being movable between a first and a second ball valve position to selectively couple one of the first and second fluid passageways to the common spill passageway.