A fuel pump includes an output shaft of a motor and an impeller configured to rotate integrally with the output shaft. An outer periphery of the output shaft includes a first flat portion for engaging with the impeller. The impeller includes a through hole at a center thereof, the through hole being larger than an outer diameter of the output shaft and including a second flat portion for engaging with the output shaft. In this fuel pump, when the output shaft and the impeller are arranged coaxially, spots exist which have different lengths of a gap between the first flat portion and the second flat portion in a rotational axis direction of the output shaft.

A submersible well pump assembly has upper and lower seal sections connected between the pump and a motor. The seal sections have drive shafts with thrust runners that engage thrust bearing bases. The upper drive shaft will undergo a limited amount of downward movement toward the lower drive shaft in response to wear of the upper thrust bearing base. A spring between ends of the drive shafts transfers a portion of the down thrust on the upper drive shaft to the lower drive shaft prior to the limited amount of downward movement of the upper drive shaft toward the lower drive shaft being reached. A rigid stop member in the coupling transfers down thrust directly from the upper drive shaft to the lower drive shaft, bypassing the spring, only after the limited amount of downward movement of the upper drive shaft toward the lower drive shaft has been reached.

A rotary machine includes a cylindrical rotary shaft extending in a direction of an axis, a fastening bolt having a bolt body that extends in a direction of an axis 0 in the rotary shaft to form fastening portions at both ends, a pair of rotary bodies each having an end portion in the direction of the axis that is fixed to each of the pair of fastening portions to be in contact with an end surface of the rotary shaft in the direction of the axis, and a bolt extension mechanism that temporarily extends the bolt body in the direction of the axis.

A rotary machine includes a cylindrical rotary shaft extending in a direction of an axis, a fastening bolt having a bolt body that extends in a direction of an axis 0 in the rotary shaft to form fastening portions at both ends, a pair of rotary bodies each having an end portion in the direction of the axis that is fixed to each of the pair of fastening portions to be in contact with an end surface of the rotary shaft in the direction of the axis, and a bolt extension mechanism that temporarily extends the bolt body in the direction of the axis.

An oil pump drive device (1) may include a housing (G), an oil pump drive shaft (AN), an electric motor, and a planetary gear set (RS). The planetary gear set (RS) may be supported by the housing (G) and have a first element (E1) connected to a rotor (R) of the electric motor, a second element (E2) connected to the oil pump drive shaft (AN), and a third element (E3) drivable by a drive source located outside the oil pump drive device (1). A first bearing (L1) may be supported on the housing (G) and may support at least one of the elements (E1, E2, E3) of the planetary gear set (RS) in a radial direction. The stator (S) of the electric motor is at least partially surrounded by a plastic mass (K), where the stator (S) is attached to the housing (G) via the plastic mass (K).

An oil pump drive device (1) may include a housing (G), an oil pump drive shaft (AN), an electric motor, and a planetary gear set (RS). The planetary gear set (RS) may be supported by the housing (G) and have a first element (E1) connected to a rotor (R) of the electric motor, a second element (E2) connected to the oil pump drive shaft (AN), and a third element (E3) drivable by a drive source located outside the oil pump drive device (1). A first bearing (L1) may be supported on the housing (G) and may support at least one of the elements (E1, E2, E3) of the planetary gear set (RS) in a radial direction. The stator (S) of the electric motor is at least partially surrounded by a plastic mass (K), where the stator (S) is attached to the housing (G) via the plastic mass (K).

A split can for a magnetic coupling includes a cylindrical jacket region and a base region connected to a first end of the jacket region. The jacket region has an inner wall and an outer wall enclosing the inner wall. The inner wall and the outer wall are spaced apart from each other in the radial direction by a gap, with the inner wall being integrally joined to the outer wall by a plurality of webs. The gap may be provided with a control medium which may be monitored to detect changes in one or more characteristics of the control medium indicative of split can leakage.

A system for hydraulically fracturing an underground formation in an oil or gas well, including a pump for pumping hydraulic fracturing fluid into the wellbore, the pump having a pump shaft, and an electric motor with a motor shaft mechanically attached to the pump to drive the pump. The system further includes a torsional coupling connecting the motor shaft to the pump shaft. The torsional coupling includes a motor component fixedly attached to the motor shaft and having motor coupling claws extending outwardly away from the motor shaft, and a pump component fixedly attached to the pump shaft of the pump and having pump coupling claws extending outwardly away from the pump shaft. The motor coupling claws engage with the pump coupling claws so that when the motor shaft and motor component rotate, such rotation causes the pump component and the pump shaft to rotate, thereby driving the pump.

A system for hydraulically fracturing an underground formation in an oil or gas well, including a pump for pumping hydraulic fracturing fluid into the wellbore, the pump having a pump shaft, and an electric motor with a motor shaft mechanically attached to the pump to drive the pump. The system further includes a torsional coupling connecting the motor shaft to the pump shaft. The torsional coupling includes a motor component fixedly attached to the motor shaft and having motor coupling claws extending outwardly away from the motor shaft, and a pump component fixedly attached to the pump shaft of the pump and having pump coupling claws extending outwardly away from the pump shaft. The motor coupling claws engage with the pump coupling claws so that when the motor shaft and motor component rotate, such rotation causes the pump component and the pump shaft to rotate, thereby driving the pump.

A cylindrical gap is formed between a production pipe and a pump stator, the pump stator has a tubular pump casing that surrounds a plurality of pump bodies, the pump casing is provided with a penetrating portion that penetrates the pump casing in a radial direction and communicates with the gap, and the penetrating portion is formed in a portion of the pump casing that faces a pump body, which is located in an intermediate stage of the plurality of pump bodies, in the radial direction.