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.

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.

A hydraulic device comprises an outer surface of a rotor rotating and facing an outer surface of a port member. The rotor has a plurality of cylinders disposed about an axis and cooperating pistons. The cylinders communicate with respective open ends at the rotor outer surface. Each open end alternatingly communicates with high and low pressure ports. Each two successive cylinders are interconnected via a fluid displacement member having first and second openings communicating with each respective cylinder and a closure element that obstructs either the first or second opening if the pressure in the cylinder that communicates with the second opening is higher or lower than the pressure in the cylinder that communicates with the first opening, respectively. The first opening and the second opening of each two fluid displacement members which communicate with one cylinder are fluidly connected with that cylinder at opposite sides of a flow resistance.

A hydraulic device comprises an outer surface of a rotor rotating and facing an outer surface of a port member. The rotor has a plurality of cylinders disposed about an axis and cooperating pistons. The cylinders communicate with respective open ends at the rotor outer surface. Each open end alternatingly communicates with high and low pressure ports. Each two successive cylinders are interconnected via a fluid displacement member having first and second openings communicating with each respective cylinder and a closure element that obstructs either the first or second opening if the pressure in the cylinder that communicates with the second opening is higher or lower than the pressure in the cylinder that communicates with the first opening, respectively. The first opening and the second opening of each two fluid displacement members which communicate with one cylinder are fluidly connected with that cylinder at opposite sides of a flow resistance.

A plunger pump fluid end assembly design in which the suction valve and seat is aligned with the plunger and the fluid end housing is constructed with multiple modules. Modules are held in a rigid assembly by staybolts that connect to the power end of the plunger pump. Said staybolts pass though bores in the central fluid module and the suction seat module and bound by a conventional threaded nut. Packing box modules are bound to the central fluid module by bolts that also pass through separate bores in the same central module. A suction valve spring retainer/plunger spacer within the plunger bore of the assembly shields the intersection of the plunger bore and the discharge bore from destructive erosion damage.

A method is provided for forming wear-resistant layer on the surface of cylinder bores a cylinder drum of a hydrostatic axial piston machine within which a respective piston is moved in a manner subject to intensive wear. The cylinder bores are gas nitrocarburized in two stages to minimize the wear and include a thin uniform connecting layer that has a thickness of 4 to 16 m and a comparatively thick underlying diffusion layer.

Positive displacement machines and methods therefor capable of increasing a load-carrying capacity of a piston-cylinder lubrication interface of positive displacement machines having a cylinder block, a cylindrical bore defined in the cylinder block, a piston reciprocably disposed within the cylindrical bore, and a working fluid within the piston-cylinder lubrication interface to provide a load-bearing function between the piston and the bore wall of the cylinder bore. The method includes providing at least one circumferential groove on a bore wall of the cylindrical bore within the piston-cylinder lubrication interface having an opening facing the piston and that is in fluidic communication with the piston-cylinder lubrication interface so as to contain a portion of the working fluid, and operating the positive displacement machine such that the working fluid enters the cylindrical groove and promotes hydrostatic balancing of pressure of the working fluid within the piston-cylinder lubrication interface.

This describes an axial piston pump (1, 1) with inclined plate for pumping a liquid comprising: a head (20) in which there are at least partially made a plurality of cylinders (25a, 25b, 25c, 25d, 25e) in a number greater than three, with central axes parallel to each other, a plurality of pistons (75) each one sliding in a respective cylinder (25a, 25b, 25c, 25d, 25e) of the plurality of cylinders (25a, 25b, 25c, 25d, 25e) for pumping liquid, a plurality of suction valves (115), each one housed in a respective housing seat made in the head (20), a plurality of suction channels (155a, 155b, 155c, 155d, 155e) made in the head, one for each suction valve (115), each of which, independently from the other suction channels, places a housing seat of a suction valve (115) in fluid communication with the corresponding cylinder (25a, 25b, 25c, 25d, 25e), a plurality of delivery valves (120), each one housed in a respective housing seat made in the head (20), a plurality of delivery channels (160a, 160b, 160c, 160d, 160e) made in the head, one for each delivery valve (120), each of which, independently from the other delivery channels, places a cylinder (25a, 25b, 25c, 25d, 25e) in fluid communication with the housing seat of the corresponding delivery valve (120).

This describes an axial piston pump (1, 1) with inclined plate for pumping a liquid comprising: a head (20) in which there are at least partially made a plurality of cylinders (25a, 25b, 25c, 25d, 25e) in a number greater than three, with central axes parallel to each other, a plurality of pistons (75) each one sliding in a respective cylinder (25a, 25b, 25c, 25d, 25e) of the plurality of cylinders (25a, 25b, 25c, 25d, 25e) for pumping liquid, a plurality of suction valves (115), each one housed in a respective housing seat made in the head (20), a plurality of suction channels (155a, 155b, 155c, 155d, 155e) made in the head, one for each suction valve (115), each of which, independently from the other suction channels, places a housing seat of a suction valve (115) in fluid communication with the corresponding cylinder (25a, 25b, 25c, 25d, 25e), a plurality of delivery valves (120), each one housed in a respective housing seat made in the head (20), a plurality of delivery channels (160a, 160b, 160c, 160d, 160e) made in the head, one for each delivery valve (120), each of which, independently from the other delivery channels, places a cylinder (25a, 25b, 25c, 25d, 25e) in fluid communication with the housing seat of the corresponding delivery valve (120).

In an embodiment, a pump includes a pump housing formed as a singular body. The pump housing may include a mounting feature adjacent a first end of the pump housing. The mounting feature may be configured for mounting the pump relative to a prime mover. A drive system cavity may be formed in the first end of the pump housing, and sized to receive at least a portion of an axial drive system. A pump cylinder may extend inwardly into the pump housing from the drive system cavity. A piston guide plate may be configured to be affixed within the drive system cavity. The piston guide plate includes a piston guide associated with the pump cylinder. The piston guide may be configured to at least partially receive a pump piston therethrough for facilitating alignment and axial movement of a pump piston within the pump cylinder.