A fuel pump assembly for a gas turbine engine includes a shaft for transmitting motion, a gear connected to and coaxial with the shaft with the gear having a first wear surface, a first bearing coaxial with the shaft with the first bearing being configured to support the gear and having a second wear surface positioned to interact with the first wear surface, and a plurality of indents. The indents are distributed in the first wear surface or the second wear surface and at least two of the plurality of indents are partially aligned in a radial direction.

A fuel pump assembly for a gas turbine engine includes a shaft for transmitting motion, a gear connected to and coaxial with the shaft with the gear having a first wear surface, a first bearing coaxial with the shaft with the first bearing being configured to support the gear and having a second wear surface positioned to interact with the first wear surface, and a plurality of indents. The indents are distributed in the first wear surface or the second wear surface and at least two of the plurality of indents are partially aligned in a radial direction.

A pump housing structure of a three-axis multi-stage Roots pump is provided, comprising a first-stage pump housing, a second-stage pump housing and a third-stage pump housing, wherein the first-stage pump housing is provided with a first center axial hole, a first left axial hole and a first right axial hole; a fixed bearing end cover is mounted on the side of the first-stage pump housing, three fixed bearing chambers are provided on the surface of the fixed bearing end cover; the second-stage pump housing is provided with a second center axial hole, a second left axial hole and a second right axial hole, the third-stage pump housing is provided with a third center axial hole, a third left axial hole and a third right axial hole, and the end surface at the outer side of the third-stage pump housing is fixedly mounted with a non-driving end bearing end cover. The present invention can accommodate and fix three axes through three fixed bearing chambers, respectively. Moreover, since the sum of the axial lengths of the second-stage pump housing and the third-stage pump housing is equal to the axial length of the first-stage pump housing, it not only can strengthen the center stiffness of the three axes of the Roots pump, but also can ensure that the total axial expansion is evenly divided, reducing the cumulated amount of thermal expansion at the end of the axis.

A pump housing structure of a three-axis multi-stage Roots pump is provided, comprising a first-stage pump housing, a second-stage pump housing and a third-stage pump housing, wherein the first-stage pump housing is provided with a first center axial hole, a first left axial hole and a first right axial hole; a fixed bearing end cover is mounted on the side of the first-stage pump housing, three fixed bearing chambers are provided on the surface of the fixed bearing end cover; the second-stage pump housing is provided with a second center axial hole, a second left axial hole and a second right axial hole, the third-stage pump housing is provided with a third center axial hole, a third left axial hole and a third right axial hole, and the end surface at the outer side of the third-stage pump housing is fixedly mounted with a non-driving end bearing end cover. The present invention can accommodate and fix three axes through three fixed bearing chambers, respectively. Moreover, since the sum of the axial lengths of the second-stage pump housing and the third-stage pump housing is equal to the axial length of the first-stage pump housing, it not only can strengthen the center stiffness of the three axes of the Roots pump, but also can ensure that the total axial expansion is evenly divided, reducing the cumulated amount of thermal expansion at the end of the axis.

Described herein is a mechanism including: a driving shaft comprising an eccentric crank and an arm part extending radially from the driving shaft, the arm part of the driving shaft comprising a piston housing; a piston in the piston housing; an eccentric lever bushing comprising an arm part extending radially therefrom, a cylindrical outer surface and a cylindrical hole, wherein the cylindrical hole is rotatably attached to the eccentric crank, wherein an axis of the cylindrical hole and an axis of the cylindrical outer surface are parallel and offset; wherein the piston is configured to apply a torque on the eccentric lever bushing by pushing the arm part of the eccentric lever bushing. The driving shaft may further comprise a channel configured to apply fluid pressure on the piston. This mechanism may be used in a device such as a star scroll compressor.

Described herein is a mechanism including: a driving shaft comprising an eccentric crank and an arm part extending radially from the driving shaft, the arm part of the driving shaft comprising a piston housing; a piston in the piston housing; an eccentric lever bushing comprising an arm part extending radially therefrom, a cylindrical outer surface and a cylindrical hole, wherein the cylindrical hole is rotatably attached to the eccentric crank, wherein an axis of the cylindrical hole and an axis of the cylindrical outer surface are parallel and offset; wherein the piston is configured to apply a torque on the eccentric lever bushing by pushing the arm part of the eccentric lever bushing. The driving shaft may further comprise a channel configured to apply fluid pressure on the piston. This mechanism may be used in a device such as a star scroll compressor.

A fuel pump assembly for a gas turbine engine includes a shaft for transmitting motion, a gear connected to and coaxial with the shaft with the gear having a first wear surface, a first bearing coaxial with the shaft with the first bearing being configured to support the gear and having a second wear surface positioned to interact with the first wear surface, and a plurality of indents. The indents are distributed in the first wear surface or the second wear surface and at least two of the plurality of indents are partially aligned in a radial direction.

A fuel pump assembly for a gas turbine engine includes a shaft for transmitting motion, a gear connected to and coaxial with the shaft with the gear having a first wear surface, a first bearing coaxial with the shaft with the first bearing being configured to support the gear and having a second wear surface positioned to interact with the first wear surface, and a plurality of indents. The indents are distributed in the first wear surface or the second wear surface and at least two of the plurality of indents are partially aligned in a radial direction.

A controlled variable delivery external gear machine (VD-EGM). The VD-EGM includes a housing, an inlet, a drive gear, a driven gear, the drive gear configured to engage the driven gear in an angular mesh zone, an outlet, a first slider comprising a first longitudinal portion connected to a second longitudinal portion such that longitudinal forces applied to the first and second longitudinal portions substantially cancel each other thereby requiring between about 0 N to about 20 N to longitudinally moving the first slider, selective positioning of the first slider configured to vary net operational volumes of fluid communication between the inlet and the outlet, for a given rotational speed of the drive gear, and a first drive mechanism coupled to the first slider and configured to cause the first slider to slide in a longitudinal direction.

A pump housing structure of a three-axis multi-stage Roots pump is provided, comprising a first-stage pump housing, a second-stage pump housing and a third-stage pump housing, wherein the first-stage pump housing is provided with a first center axial hole, a first left axial hole and a first right axial hole; a fixed bearing end cover is mounted on the side of the first-stage pump housing, three fixed bearing chambers are provided on the surface of the fixed bearing end cover; the second-stage pump housing is provided with a second center axial hole, a second left axial hole and a second right axial hole, the third-stage pump housing is provided with a third center axial hole, a third left axial hole and a third right axial hole, and the end surface at the outer side of the third-stage pump housing is fixedly mounted with a non-driving end bearing end cover. The present invention can accommodate and fix three axes through three fixed bearing chambers, respectively. Moreover, since the sum of the axial lengths of the second-stage pump housing and the third-stage pump housing is equal to the axial length of the first-stage pump housing, it not only can strengthen the center stiffness of the three axes of the Roots pump, but also can ensure that the total axial expansion is evenly divided, reducing the cumulated amount of thermal expansion at the end of the axis.