A gas pump including a delivery chamber with an inlet and an outlet for a gas. The delivery chamber is at least partially enclosed by a first housing part with a first sealing surface and a second housing part with a second sealing surface. A delivery device is moveable within the delivery chamber for delivering the gas. A pressing device presses one of the housing parts against the other with a pressing force such that the sealing surfaces abut each other and together form a sealing join which at least partially surrounds the delivery chamber in order to seal off the delivery chamber. The second housing part can be moved relative to the first housing part, against the pressing force, in order to be able to widen the sealing join to form a relieving gap through which liquid situated in the delivery chamber can escape.

A pump assembly comprising a casing having a first pump chamber defining a first flow path and a second pump chamber or more defining a second flow path. A first pump stage includes a first shaft mounted to the casing for rotation about a rotation axis, a first pair of intermeshing gears disposed in the first flow path of the first pump chamber, the first pair of intermeshing gears interfacing each other in operative engagement, one intermeshing gear of the first pump stage mounted on the first shaft. A second pump stage includes a second shaft mounted to the casing for rotation about a rotation axis different than the rotation axis of the first shaft, a second pair of intermeshing gears disposed in the second flow path of the at least second pump chamber, the second pair of intermeshing gears interfacing each other in operative engagement, one intermeshing gear of the second pump stage mounted on the second shaft. A transmission drivingly engages the first shaft to the second shaft.

An example crescent seal assembly comprises: an outer crescent of a gear pump; an inner crescent of the gear pump mating with the outer crescent such that an exterior peripheral surface of the inner crescent interfaces with an interior peripheral surface of the outer crescent, forming: (i) a spring cavity, (ii) a first check valve cavity, and (iii) a second check valve cavity therebetween; a spring disposed in the at least one spring cavity; a first check pin disposed in the first check valve cavity; and a second check pin disposed in the second check valve cavity.

A fluid working system such as a pump for displacing a working fluid such as hydraulic fluid or a motor using a working fluid is provided. The system may have a positive displacement machine which includes one or more working chamber with displacement means such as a cylinder with a reciprocating piston. There are also two or more fluid ports to allow the working fluid to flow into and out of the working chamber. The working fluid flows from one fluid port means to another either being forced to do so when pumped or moving the piston when functioning as an engine. The fluid working system has associated therewith a non-dead compliance volume of a material such as syntactic foam. This compliance volume acts to smooth any pressure fluctuations within the working fluid system.

A progressing cavity pump has: a stator; a rotor; the rotor having a first axial operating position within the stator in which a first axial part of the rotor aligns with a first axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator; the rotor having a second axial operating position within the stator in which the first axial part of the rotor aligns with a second axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator. A related method is disclosed.

A progressing cavity pump has: a stator; a rotor; the rotor having a first axial operating position within the stator in which a first axial part of the rotor aligns with a first axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator; the rotor having a second axial operating position within the stator in which the first axial part of the rotor aligns with a second axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator. A related method is disclosed.

Gerotor pump comprising an inner gerotor and an outer gerotor and an electric motor in a pump housing, and the outer gerotor is formed integrally with the rotor of the electric motor, wherein magnets are integrated into the outer gerotor, and the rotor is rotatably mounted on a shaft that is fixed on one side to a housing or a housing base of the pump housing.

According to one embodiment, a crank portion is formed from a crank piece, an element separate from a shaft portion. The crank piece includes a fitting hole in which the shaft portion is fit by predetermined “interference” and a slit-like slot with one end opened in an inner circumferential surface of the fitting hole, and an other end closed inside the crank piece. The fitting hole is deformed so as to expand its diameter when expanding a width of the slot. The shaft portion is fit in the fitting hole of the crank piece by the predetermined “interference” when inserted in the deformed fitting hole and the fitting hole restores an original form while the shaft portion is in the fitting hole.

Positive displacement machine such as a compressor, expander, pump or the like, for displacing a gaseous or liquid medium, the machine containing an element with at least one inlet and at least one outlet for the medium and at least two cooperating driven moving parts. The mutual periodic movement of the moving parts displaces the medium from the inlet to the outlet. Each of the at least two driven cooperating moving parts is provided with its own individual drive. The element is provided with a kinematic synchronisation coupling between the at least two cooperating moving parts for the mutual kinematic synchronisation of their movements.

A crankshaft assembly, a compressor and a refrigeration device are provided. The crankshaft assembly has an eccentric shaft component, a spindle component and a main screw oil pump. The eccentric shaft component has an eccentric cavity, and the spindle component has a first cavity communicated with the eccentric cavity. A first through-hole and a second through-hole in a first spindle are each communicated with the first cavity. An outer surface of the first spindle is provided with a first spiral oil groove connecting the first through-hole and the second through-hole. An outer surface of the main screw oil pump is provided with a second spiral oil groove along its length direction, and a spiral direction of the second spiral oil groove is opposite that of the first spiral oil groove.