A modular expansion assembly for a gear pump is provided. The modular expansion assembly includes a case extension, a set of elongated replacement gears, and a set of elongated replacement shafts. The case extension is removably attached between a main case of the gear pump and a faceplate assembly of the gear pump. The case extension includes a second chamber that aligns with a first chamber of the main case to form a continuous combined chamber. The set of replacement gears is configured to extend axially the substantial length of the continuous combined chamber, and the set of replacement shafts is configured to extend through the continuous combined chamber into bores of the faceplate assembly and bores of a backplate assembly of the gear pump. When installed on a gear pump, the modular expansion assembly allows for increased volumetric displacement without requiring changes to connecting piping systems.

A drive system for a multistage screw compressor with a first compressor stage with a first main rotor mounted on a first shaft in a torque-proof manner and a second compressor stage with a second main rotor mounted on a second shaft in a torque-proof manner. The drive system has a drive shaft for driving the shafts of both main rotors of the first and second compressor stages, wherein the driving of the shaft of the first main rotor takes place independently of the driving of the shaft of the second main rotor, so that the rotational speeds of the two main rotors can preferably be adapted independently of one another.

A method is used to manufacture a plurality of pumps with different performance properties. Each pump can have a pump housing or a pump housing portion for holding gear wheels in engagement. A plurality of identical universal pump blanks can be primary shaped to create a plurality of identical primary shaped pump blanks. A first operative pump can then be created with a first unique performance property, and a second operative pump can be created with a second unique performance property different from the first unique performance property.

A system includes an electric submersible progressive cavity pump (ESPCP). The ESPCP includes a stator having an internal bore, and a hollow rotor disposed in the internal bore of the stator, where the hollow rotor is configured to rotate within the internal bore to pump a fluid via a plurality of progressive cavities.

A system includes an electric submersible progressive cavity pump (ESPCP). The ESPCP includes a stator having an internal bore, and a hollow rotor disposed in the internal bore of the stator, where the hollow rotor is configured to rotate within the internal bore to pump a fluid via a plurality of progressive cavities.