A piston pump includes a rotor member with a bore therein. The bore is defined by an inner surface. The piston pump also includes a piston supported for reciprocating movement in an axial direction within the bore to change a volume of a pump chamber that is cooperatively defined by the piston and the rotor member. The piston has an outer surface that faces the inner surface with a leakage interface defined therebetween. The leakage interface is configured to receive a passive leakage flow of a fluid from the pump chamber through the leakage interface to provide cooling. Moreover, the outer surface includes a relief feature that is recessed into the outer surface to define, with the inner surface, a cooling pocket of the leakage interface. The cooling pocket moves in the axial direction relative to the inner surface with the reciprocating movement of the piston.

A pump draws fluid from a reservoir and drives the fluid downstream to a spray tip where the fluid is applied to a surface. The pump includes a polymer pump body and a metallic piston configured to reciprocate relative to and within the polymer pump body. The metallic piston interfaces with an inner cylinder formed within the polymer pump body and pumps fluid through the polymer pump body to a spray nozzle downstream of the inner cylinder.

An axial piston device may be operated as a pump and includes a self-centering rotary valve. The device includes a stationary housing encompassing a shaft and the rotary valve. The rotary valve and the shaft are coupled to each other. Upon rotation, the rotary valve self-centers as a result of elimination of moments and forces within the pump. The inventive pump is a piston device. The valve is within a valve bore, which is a part of a manifold. A shaft is within the manifold and the shaft is attached at its distal end to a planar surface of the rotary valve. The shaft has a first axis of rotation and the rotary valve has a second axis of rotation. During operation of the pump, the first axis is often times offset from the second axis. The pump operates via a swashplate with reciprocating pistons while the housing remains stationary.

An axial piston device may be operated as a pump and includes a self-centering rotary valve. The device includes a stationary housing encompassing a shaft and the rotary valve. The rotary valve and the shaft are coupled to each other. Upon rotation, the rotary valve self-centers as a result of elimination of moments and forces within the pump. The inventive pump is a piston device. The valve is within a valve bore, which is a part of a manifold. A shaft is within the manifold and the shaft is attached at its distal end to a planar surface of the rotary valve. The shaft has a first axis of rotation and the rotary valve has a second axis of rotation. During operation of the pump, the first axis is often times offset from the second axis. The pump operates via a swashplate with reciprocating pistons while the housing remains stationary.

A hydraulic machine includes a first member (1) having a first structure (2) for a hydraulic medium opening in a first interface surface (3) and a second member having a second structure for the hydraulic medium opening in a second interface surface is described, the first interface surface (3) being in contact with the second interface surface, wherein at least one of the members (1) is provided with a support element (6) surrounding the member (1). Such a machine should have a good efficiency. To this end the support element (6) has a strength varying in circumferential direction around the member (1) and/or in thickness direction in a middle region of the member (1).

A piston pump (1) is described for pumping a liquid comprising: a head (10) wherein at least a cylinder (15) is obtained, a piston (45) slidably inserted in the cylinder, a first sealing annular gasket (60) which circumferentially sealingly contacts the piston (45), a second sealing annular gasket (80) which circumferentially sealingly contacts the piston, and an annular body (100) which circumferentially encloses the piston (45) and is at least partially accommodated in a housing seat (110) obtained in the head (10) in a portion of the cylinder (15). Said annular body (100) comprises: a first housing seat (150) wherein the first sealing annular gasket (60) is housed, a second housing seat (155) wherein the second sealing annular gasket (80) is housed, and a third housing seat (185) wherein a third sealing annular gasket (190) is housed, which is placed between the annular body (100) and the housing seat (110) of the annular body.

A shaft-distributed double-acting roller piston pump includes a front end cover, a pump casing, a rear end cover and a pump core assembly. The pump core assembly includes a guide rail assembly including left and right guide rails arranged back to back. The side surfaces of the left and right guide rails away from each other are space cam curved surfaces. A flow distribution shaft is installed in the center of the guide rail assembly. A cylinder assembly is installed on both sides of the guide rail assembly including left and right cylinders, between which a piston assembly is arranged. The piston assembly forms left and right closed cavities with the left and right cylinders respectively. The piston assembly performs axial reciprocating linear motion under the constraint of the cylinder assembly and the guide rail assembly, and the volumes of the left and right closed cavities change continuously.

A shaft-distributed double-acting roller piston pump includes a front end cover, a pump casing, a rear end cover and a pump core assembly. The pump core assembly includes a guide rail assembly including left and right guide rails arranged back to back. The side surfaces of the left and right guide rails away from each other are space cam curved surfaces. A flow distribution shaft is installed in the center of the guide rail assembly. A cylinder assembly is installed on both sides of the guide rail assembly including left and right cylinders, between which a piston assembly is arranged. The piston assembly forms left and right closed cavities with the left and right cylinders respectively. The piston assembly performs axial reciprocating linear motion under the constraint of the cylinder assembly and the guide rail assembly, and the volumes of the left and right closed cavities change continuously.

A pump power end frame with a fatigue-resistant crankshaft housing machined from a one-piece forging may include machined features and bolted-on accessories. The crankshaft housing and the accessories have no welds that are subject to cracking in response to cyclic stresses due to operation of the pump.

A pump power end frame with a fatigue-resistant crankshaft housing machined from a one-piece forging may include machined features and bolted-on accessories. The crankshaft housing and the accessories have no welds that are subject to cracking in response to cyclic stresses due to operation of the pump.