Abstract: In accordance with at least one aspect of this disclosure, a system includes, a cylinder barrel configured to rotate within a pump housing of a pump operatively connected to a driving member of the pump via a first shaft. A piston is seated within a bore defined in the cylinder barrel. The piston is operatively connected to the driving member of the pump via a second shaft. The first shaft and the second shaft each include a ball end configured to seat within the driving member. In embodiments, the ball end of at least the second shaft is of silicon nitride.

Abstract: In accordance with at least one aspect of this disclosure, a pump system for an aircraft includes, a cylinder barrel configured to rotate within a pump housing of a pump, and a plurality of pistons seated within a respective bore defined in the cylinder barrel. Each piston further includes a piston ring disposed at an end thereof configured to form a hydrodynamic seal with an inner surface of the respective bore. Each respective piston ring is of silicon nitride. In embodiments, the piston ring can include a chamfer on at least a leading edge of the piston ring. In embodiments, the piston ring can include a cut therethrough configured to allow for thermal expansion of the piston ring.

Abstract: In accordance with at least one aspect of this disclosure, a system includes, a cylinder barrel configured to rotate within a pump housing of a pump operatively connected to a driving member of the pump via a first shaft. A piston is seated within a bore defined in the cylinder barrel. The piston is operatively connected to the driving member of the pump via a second shaft. The first shaft and the second shaft each include a ball end configured to seat within the driving member. In embodiments, the ball end of at least the second shaft is of silicon nitride.

Abstract: In accordance with at least one aspect of this disclosure, a system comprises, a cylinder barrel configured to rotate within a pump housing. In embodiments, the cylinder barrel includes a main cylindrical body, a center recess defined within the main cylindrical body configured to seat a drive shaft therein, and a plurality of bores defined in the main cylindrical body, extending in an axial direction, wherein the plurality of bores are spaced apart circumferentially relative to one another about the main cylindrical body radially outward of the center recess. Each of the plurality of bores are configured to seat a respective piston therein and allow fluid flow therethrough. In embodiments, the main cylindrical body is of silicon nitride.