A crescent internal gear pump includes a front cover, an end cover, a ring gear and a pinion gear disposed within a gear housing in an eccentric, intermeshing relationship. The housing is disposed intermediate the front cover and the end cover. A crescent is disposed radially intermediate the ring gear and the pinion gear. The crescent partially extends into a correspondingly shaped slot in the end cover. The gear housing, the ring gear, and the pinion gear can have substantially the same thickness. A shim can be disposed intermediate the end cover and the gear housing for establishing a desired clearance therebetween.

Described is a method for grinding workpieces, which comprise at least one cylindrical and profiled portion each, on one and the same grinding machine. The workpiece is ground initially in a first grinding operation in a first clamping in the grinding machine, said first grinding operation being followed by a second grinding operation once the first clamping has been released and then, before the start of the second grinding operation, a second clamping has been generated.

A crescent internal gear pump includes a front cover, an end cover, a ring gear and a pinion gear disposed within a gear housing in an eccentric, intermeshing relationship. The housing is disposed intermediate the front cover and the end cover. A crescent is disposed radially intermediate the ring gear and the pinion gear. The crescent partially extends into a correspondingly shaped slot in the end cover. The gear housing, the ring gear, and the pinion gear can have substantially the same thickness. A shim can be disposed intermediate the end cover and the gear housing for establishing a desired clearance therebetween.

A screw rotor lead correction calculation device includes an initial data input section configured to input an error as a distance with respect to a reference lead at each axial position of a rotor groove portion of a screw rotor, and a processing machine input correction amount/position output section configured to compute and output, based on the error as the distance input to the initial data input section, a lead correction amount with respect to the reference lead and a lead correction starting position as an axial position for starting lead correction. With this configuration, correction data for obtaining a screw rotor with a high-accuracy lead can be obtained from a lead error with respect to a reference lead in a screw rotor obtained by ground finish of the material of the screw rotor.

A method produces a housing of a rotary screw compressor, the housing having at least one housing body and at least one housing cover. The method includes the following steps: bearing seats for at least one screw rotor of the rotary screw compressor are provided in the housing body and in the housing cover; at least one screw borehole for the at least one screw rotor of the rotary screw compressor is provided in the housing body; the housing body and the housing cover are temporarily assembled using at least one alignment tool for ensuring the alignment of the screw rotor central axis with the central axes of the bearing seats and the screw borehole; and at least one bolt insertion opening is provided in both the housing body and the housing cover by at least one common production process.

A method produces at least one first screw bearing seat and at least one first inner wall region in a rotor housing. The rotor housing is part of a housing of a screw compressor. The method orients the rotor housing of the screw compressor, and produces the first screw bearing seat and the first inner wall region of the rotor housing in at least one joint production operation.

A screw rotor lead correction calculation device includes an initial data input section configured to input an error as a distance with respect to a reference lead at each axial position of a rotor groove portion of a screw rotor, and a processing machine input correction amount/position output section configured to compute and output, based on the error as the distance input to the initial data input section, a lead correction amount with respect to the reference lead and a lead correction starting position as an axial position for starting lead correction. With this configuration, correction data for obtaining a screw rotor with a high-accuracy lead can be obtained from a lead error with respect to a reference lead in a screw rotor obtained by ground finish of the material of the screw rotor.

An improved progressing cavity pump, methods of making the same, methods of using the same, and methods of retrofitting conventional progressing cavity pumps are disclosed. The improved progressing cavity pump has an improved polished rod, which is connectable to a slider tool, that enables the rod string, including the pump's rotor to be lowered in the production tubing without requiring disassembly of the above ground equipment. Preferably, the slider tool functions to extend the length of the improved polished rod, and the connection between the slider tool and the improved polished rod is preferably configured to ensure that the outside diameter of the connection is no larger than the passageways of the above ground equipment it needs to pass through, when it is lowered. Also disclosed is an improved polished rod clamp. An indicator which enables an operator on the ground to visually determine whether a progressing cavity pump is operating, or whether it is operating correctly is also disclosed.

A suction side end part of a suction guide passage and a discharge side end part of a discharge guide passage are opposed to each other with a gap therebetween. At a deviation angle at which contraction of a pump chamber starts, an outer peripheral part of the discharge side end part is formed along an inner tooth, and an inner peripheral part of the discharge side end part is formed along an outer tooth. A working tool that rotates and cuts circularly is moved around on a pump housing in a single continuous line to form an outline of the discharge guide passage, thereby forming the discharge guide passage. The working tool is moved around on the pump housing in a single continuous line to form an outline of the suction guide passage, thereby forming the suction guide passage.

A method for forming drilled cast which includes drilling with a drill so as to provide communication with a cast hole includes a casting step and a drilling step. The casting step is to cast a cast having a cast hole which includes a flat inner wall surface in which width of a position to be drilled with the drill is obtained by adding first length H1 serving as a manufacturing error range of the cast to a diameter D of the drill, which is a second length H2. The drilling step is to form a through hole providing communication between an interior of the cast hole and an exterior of the cast through the flat inner wall surface with the drill.