A piston pump and a piston motor are provided. The piston pump includes a cylinder body, a piston, a main shaft, an end cover, and an oil dispensing mechanism. The oil dispensing mechanism includes an oil suction mechanism and an oil discharging mechanism. A roller is mounted on the piston, and the roller is rotatablely connected to the piston. A driving wheel is arranged on the main shaft, and the driving wheel is mounted in cooperation with the main shaft or is integrally formed with the main shaft. A driving groove is formed on the driving wheel, and a roller-path surface of the driving groove is a curved surface. The size of the driving groove is adapted to the size of an outer circle of the roller. The main shaft rotates to drive the driving wheel to rotate to further drive the piston to move along the cylinder bore.

A piston pump and a piston motor are provided. The piston pump includes a cylinder body, a piston, a main shaft, an end cover, and an oil dispensing mechanism. The oil dispensing mechanism includes an oil suction mechanism and an oil discharging mechanism. A roller is mounted on the piston, and the roller is rotatablely connected to the piston. A driving wheel is arranged on the main shaft, and the driving wheel is mounted in cooperation with the main shaft or is integrally formed with the main shaft. A driving groove is formed on the driving wheel, and a roller-path surface of the driving groove is a curved surface. The size of the driving groove is adapted to the size of an outer circle of the roller. The main shaft rotates to drive the driving wheel to rotate to further drive the piston to move along the cylinder bore.

A linear frac pump includes a fluid end having an inlet valve disposed proximate to an inlet port, and a discharge valve disposed proximate to a discharge port. The pump further includes a first plunger rod housed within a first plunger housing, the first plunger rod having first and second ends, the first end being in fluid communication with the fluid end, and the second end being coupled to a first actuator. The pump includes a second plunger rod housed within a plunger housing, the second plunger rod having first and second ends, the first end being in fluid communication with the fluid end, and the second end being coupled to a second actuator. The first and second plunger rods and housings are coupled to the fluid end and the first and second plunger rods operate in sync to drive fluids inward from the inlet port and outward via the discharge port being regulated by the inlet and discharge valves.

A fuel injection pump includes: a tappet configured to reciprocate by rotation of a cam; a cylinder that supports the tappet to reciprocate; and a plunger configured to reciprocate with the tappet. The tappet includes: a tappet body supported by the cylinder to reciprocate; a pin supported on both sides in an axial direction of the pin by the tappet body; a roller rotatably fitted to an outer peripheral side of the pin; a washer disposed between at least one end surface of the roller in the axial direction and an inner peripheral surface of the tappet body. The washer has at least one protrusion to be in contact with a stopper of the tappet body in either of two rotational directions.

Changing a cumulative pumping rate of multiple pump units by adjusting individual pumping rates of the pump units, wherein each temporary dip or spike of an individual pumping rate of one of the pump units is automatically offset by a predetermined temporary adjustment of an individual pumping rate of another one or more of the pump units to thereby reduce effects of the temporary dip or spike on the cumulative pumping rate of the pump units.

A positive displacement pump includes a suction cover disposed in a suction access bore defined in the fluid end and housing, where the suction cover is configured to cover the suction access bore. A retainer nut is configured for abutting against the suction cover and retaining the suction cover within the suction access bore. A suction gland has an inner circumferential threaded interface configured to engage an external circumferential threaded interface defined on the retainer nut, and the suction gland has a plurality of threaded openings configured to receive a plurality of threaded fasteners that can be used for securely fastening the suction gland to the fluid end housing.

A pinion shaft assembly for operation in a power end of a reciprocating pump includes a tubular member coupled to first pinion gear member via an interference coupling extension, possibly having a protruding alignment key operable to engage a slot formed on an inner wall of the first end of the tubular member to ensure correct rotational orientation of the first pinion gear member and the tubular member and to help prevent rotation of the first pinion gear member relative to the tubular member. The tubular member is also coupled to a second pinion gear member via an interference coupling extension, possibly having a protruding alignment key operable to engage a slot formed on an inner wall of the second end of the tubular member to ensure correct rotational orientation of the second pinion gear member and the tubular member and to help prevent rotation of the second pinion gear member relative to the tubular member.

A fluid end comprising a plurality of fluid end sections positioned in a side-by-side relationship. Each fluid end section is releasably attached to a connect plate. Each connect plate is attached to a power source using a plurality of stay rods. Each fluid end section comprises a housing in fluid communication with a pair of intake manifolds and a discharge conduit. A fluid routing plug is installed within each housing and is configured to route fluid throughout the housing. A plunger is installed within stuffing box attached to each housing. A number of features, including the location of seals within bore walls and carbide inserts within valve guides, aid in reducing or transferring wear.

A sensor system for determining a condition associated with a piston rod of a reciprocating system includes an interrogator system having a first antenna. The sensor system further includes a second antenna separated from the first antenna by an air gap distance. The second antenna is configured to be coupled to the piston rod of the reciprocating system. The second antenna is a patch antenna and is configured to communicate with the first antenna through a range of translational movement relative to the first antenna. The sensor system further includes a radio frequency sensor coupled to the second antenna. The radio frequency sensor is configured to be coupled to the piston rod of the reciprocating system, measure a characteristic associated with the piston rod of the reciprocating system, and transmit data associated with the characteristic to the first antenna of the interrogator system through the second antenna.

An apparatus according to which a power end of a reciprocating pump assembly includes a block having bores formed therethrough, and crossheads disposed in the bores and adapted to reciprocate therein. A lubrication pump is in fluid communication with the bores. The pump is operable to pump lubrication fluid into each of the bores so that the crossheads are lubricated as they reciprocate within their respective bores. In another aspect, a power end includes a crosshead block and a power frame connected thereto, the frame including rib plates and supporting the crosshead block. In yet another aspect, a method includes casting a crosshead block; fabricating rib plates; connecting the rib plates to form a frame; and connecting the cast crosshead block to the frame. In some embodiments, the power ends may be used in oilfield operations such as, for example, the cementing, acidizing, or fracturing of a subterranean wellbore.