Abstract: A pump for providing a pressurized fluid flow. The pump includes a pump casing that defines a pump chamber. A pump shaft is has a head end in the pump chamber; the head end has a circumferential outer surface. The pump shaft head end has inwardly extending piston chambers. A discharge manifold is formed in the pump shaft head end. The discharge manifold has one end in fluid communication with the piston chambers and a second end in fluid communication with a discharge conduit that extends outside of the pump casing. A piston is mounted in each piston chamber. The pistons are formed with flow-through bores that provide fluid communication between the pump chamber and the piston chambers. A suction valve associated with each piston regulates fluid flow from the pump chamber through the flow-through bore into the associated piston chamber. Discharge valves regulate fluid flow from each piston chamber into the discharge manifold.