A structure comprising a rotor body, the rotor body including a rotor shaft arranged on one end face of the rotor body, a sub-shaft cavity opened in the rotor shaft, and locating keyways symmetrically opened on both sides inside the sub-shaft cavity; a sub-shaft arranged on the other end face of the rotor body, and sub-shaft locating keyways symmetrically opened on both sides of the sub-shaft.

An inner gear includes an insertion hole, which extends through the inner gear in an axial direction, and a first balance groove, which is axially recessed at an axial end portion of the inner gear and is communicated with the insertion hole. First and second chamfered portions are formed in an inner peripheral edge of the inner gear, which is adjacent to the insertion hole. A joint member has a leg inserted into the insertion hole. An inserting direction of the leg into the insertion hole is defined as a first direction, and a direction, which is opposite from the first direction, is defined as a second direction. In a view taken in a direction perpendicular to the axial direction, at least a part of a first direction side end portion of the leg is axially placed between a first chamfered end plane and a first groove end plane.

A method for fixing rotary pistons in a rotary piston pump and a method for dismantling rotary pistons of a rotary piston pump, where the rotary piston pump has two counter-rotating rotary arranged in a pump space on drive shafts. The rotary pistons each include a seating for the drive shafts. The respective drive shaft is arranged and fixed with an end region in the seating of the respective rotary piston. A diameter of the drive shafts in the end region can be widened elastically. In an operational state, in which the rotary pistons are arranged on the respective drive shafts, a frictional connection is formed between the respective seating of the rotary piston and the end region of the respective drive shaft.

A cylinder is installed within a case, and an output shaft and an arm that is integrated thereto and extends in a radial direction are installed within the cylinder. A piston extending in an arc slides and is displaced in a circumferential direction of the cylinder within the cylinder. One end portion of the piston is rotatably connected to the arm. The cylinder is internally provided with a first pressure chamber in which the arm is housed and a second pressure chamber in which the other end portion of the arm is slidably installed. A pressure medium is fed into one of the first and second pressure chambers and discharged from the other, and the output shaft pivots in a rotational direction.

A progressive cavity pump includes a sealed drive between the rotor and universal joint. The universal joint includes a socket configured to receive a drive shaft of the rotor. A cover, such as a locking nut, is disposed over the connection between the rotor and universal joint. Seals are retained in place by the locking nut to prevent abrasive materials from entering into the interface between the rotor and the universal joint.

A flexible impeller pump designed for use in dispensing a flowable food product. The flexible impeller pump includes a cover, impeller assembly and a pump body that are assembled to create the pump without other separate components. The components can be permanently connected to each other to create a disposable pump or can be disassembled for cleaning and reuse. The impeller assembly includes an impeller shaft and a flexible impeller molded over the impeller shaft to prevent separation. The impeller assembly is received within the pump body and the cover is secured to the pump body. The cover includes a seal that is molded over the pump body to prevent separation of the seal from the cover. The impeller shaft extends through the pump body and is coupled to a drive shaft of an electric motor that is operable to drive the impeller pump.

A gerotor pump includes a casing including a pumping chamber, a fixed gear being inserted into the casing and rotating at a fixed position, including a plurality of teeth formed inside a cylinder, and including at least one fluid hole at one end of the cylinder to allow a fluid to flow from the pumping chamber or into the pumping chamber, a moving gear provided inside the fixed gear and including one less number of teeth than a number of the plurality of teeth of the fixed gear and movable in an axial direction, a gear block arranged inside the fixed gear and movable in the axial direction, a gear ring arranged outside the moving gear, in which the moving gear can be movable with respect to the gear ring in the axial direction, and a gear ring cover provided at one end of the casing and including a hole in which the gear ring is rotated.

A progressive cavity pump includes a torque input disposed on a rotational axis, a resilient stator cylinder, a screw rotor situated within the resilient stator cylinder, and a universal joint. The universal joint rotationally couples the screw rotor to the torque input, and includes a swivel block, a linkage, a universal joint coupler, and a fastener. The swivel block has opposite laterally extending trunnions. The linkage extends parallel to the rotational axis, and laterally captures the laterally extending trunnions. The universal joint coupler is disposed around the swivel block and adjacent the linkage. The fastener connects the universal joint to the swivel block. The fastener and the laterally extending trunnions cooperate to transmit torque about the rotational axis through the linkage, while permitting lateral translation of the universal joint coupler in a plane orthogonal to the rotational axis.

A flexible impeller pump designed for use in dispensing a flowable food product is disclosed. The flexible impeller pump includes a cover, impeller assembly and a pump body that are assembled to create the pump without other separate components. The components can be permanently connected to each other to create a disposable pump or can be disassembled for cleaning and reuse. The impeller assembly includes an impeller shaft and a flexible impeller molded over the impeller shaft to prevent separation. The impeller assembly is received within the pump body and the cover is secured to the pump body. The cover includes a seal that is molded over the pump body to prevent separation of the seal from the cover. The impeller shaft extends through the pump body and is coupled to a drive shaft of an electric motor that is operable to drive the impeller pump.

A pump apparatus (1) for use in mobile means of transport (100) such as semitrailers, tank trailers, tank semitrailers (101), tank trucks and trucks (102), has a drive motor (40) and a rotary piston pump (2) having two rotor units (10, 20) on rotatably mounted rotor shafts (11, 21), connected to rotor gear wheels (12, 22). A drive pinion (32) of a drive shaft (31) coupled to one of the rotor gear wheels (12) and is received in a recess (81) of the motor shaft (41).