An example hydraulic pump comprises: a housing; an input shaft extending from the housing; a seal disposed within the housing and positioned about the input shaft; and a seal guard member positioned about the input shaft and mounted to the housing at an interface between the input shaft and the housing, wherein the seal guard member is configured to allow rotation of the input shaft without rotating therewith.

An example hydraulic pump comprises: a housing; an input shaft extending from the housing; a seal disposed within the housing and positioned about the input shaft; and a seal guard member positioned about the input shaft and mounted to the housing at an interface between the input shaft and the housing, wherein the seal guard member is configured to allow rotation of the input shaft without rotating therewith.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A hydraulic piston unit including a rotational group for driving or being driven by a driving shaft, and having a tiltable displacement element for adjusting the displacement volume of the rotational group between a minimum or a maximum displacement, wherein, on t valve segment between a kidney-shaped inlet port and a kidney-shaped outlet port at respective dead end positions of reciprocally moveable working pistons first and second control ports are located in fluid connection with cylinder bores in the cylinder block, for controlling the position of the displacement element. The hydraulic piston unit further includes a control valve with a shiftable control valve spool fluidly connected via a high pressure port to a high pressure side of the hydraulic piston unit. The control valve spool is configured to conduct hydraulic fluid from the high pressure side to one of the first or the second control port.

A hydraulic piston unit including a rotational group for driving or being driven by a driving shaft, and having a tiltable displacement element for adjusting the displacement volume of the rotational group between a minimum or a maximum displacement, wherein, on t valve segment between a kidney-shaped inlet port and a kidney-shaped outlet port at respective dead end positions of reciprocally moveable working pistons first and second control ports are located in fluid connection with cylinder bores in the cylinder block, for controlling the position of the displacement element. The hydraulic piston unit further includes a control valve with a shiftable control valve spool fluidly connected via a high pressure port to a high pressure side of the hydraulic piston unit. The control valve spool is configured to conduct hydraulic fluid from the high pressure side to one of the first or the second control port.

A modular hydraulic device comprising: a housing having a receptacle having a first open end, a second end and a first port, the first port for facilitating an ingress and an egress of hydraulic fluid with respect to the housing; a sleeve configured to be received in the first open end and abut the second end; and an end cap for closing the first open end once the sleeve is inserted in the receptacle; the sleeve having: a body having a fourth lan (L4) positioned in the body for aligning with first port; a main cylinder for holding a main piston for reciprocation about a reciprocation axis; and a first bore portion fluidly coupled to the first lan, the first bore portion for receiving the ingress of the hydraulic fluid and for outputting the egress of the hydraulic fluid; wherein once assembled the main piston is coupled to a cam for facilitating said reciprocation.

Control systems and feedback assemblies for hydraulic axial displacement machines, such as pumps and motors. The control systems and feedback assemblies can have enhanced adjustability. An angle sensor for sensing the angular position of a pivot arm can have a housing, and the housing can be angularly adjustable about the pivot axis relative to the pivot arm.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.