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A planet gear for use in an air turbine starter is formed of a first part having a set of gear teeth at a first axial location. A shaft extends axially away from the first set of gear teeth. A second part is interference fit on the first part, with the second part having a second set of gear teeth.

A planet gear for use in an air turbine starter is formed of a first part having a set of gear teeth at a first axial location. A shaft extends axially away from the first set of gear teeth. A second part is interference fit on the first part, with the second part having a second set of gear teeth. The second part is mounted on the shaft of the first part. An outer diameter of the shaft is selected to be significantly larger than an inner diameter of a cylindrical portion of the second part which is interference fit on the shaft. A ratio of the outer diameter to the inner diameter is between 1.0005 and 1.0100. A planetary gear system, an air turbine starter and a method of installing a planet gear are also disclosed.

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1. A planet gear for use in an air turbine starter comprising: a first part having a first set of gear teeth at a first axial location, and having a shaft extending axially away from said first set of gear teeth;a second part interference fit on said first part, said second part having a second set

1. A planet gear for use in an air turbine starter comprising: a first part having a first set of gear teeth at a first axial location, and having a shaft extending axially away from said first set of gear teeth;a second part interference fit on said first part, said second part having a second set of gear teeth, and said second part being mounted on said shaft of said first part;an outer diameter of said first part at said shaft being selected to be significantly larger than an inner diameter of a cylindrical portion of said second part which is interference fit on said shaft, with a ratio of said outer periphery diameter of said first part to said inner diameter of said second part being between 1.0005 and 1.0100,wherein said second part has a chamber on inner end of said cylindrical portion that is adjacent to said first of gear teeth;wherein a cutout portion is provided on said first gear part between said outer diameter and said first set of gear teeth;wherein said output portion has a chamber formed between said outer diameter, and said first set of gear teeth, andwherein said inner end of said second part abuts an end face of said first part. 2. A planetary gear system for use in an air turbine starter comprising: a sun gear;a plurality of planet gears driven by said sun gear;said plurality of planet gears engaged to drive a ring gear;said planet gears, including a bearing within an inner peripheral bore in said planet gears, and a planet shaft in each said planet gear supported within said bearing, said planet shaft extending along a central axis;said planet gears being formed with a surface hardened treatment at said inner peripheral bore which runs on said bearing;each said planet gear including a first part having a first set of gear teeth at a first axial location, and having a gear shaft extending axially away from said first set of gear teeth, a second part interference fit on said first part, said second part having a second set of gear teeth, and said second part being mounted on said gear shaft of said first part, and an outer diameter of said first part at said gear shaft being selected to be significantly larger than an inner diameter of a cylindrical portion of said second part which is interference fit on said gear shaft, with a ratio of said outer diameter of said first part to said inner diameter of said second part being between 1.0005 and 1.0100;wherein said second part has a chamber on an inner end of said cylindrical portion which is adjacent to said first set of gear teeth;wherein a cutout portion is provided on said first gear part between said outer diameter and said first set of gear teeth;wherein said cutout portion has a chamber formed between said outer diameter, and said first set of gear teeth; andwherein said inner end of said second part abuts an end face of said first part. 3. An air turbine starter comprising: an air inlet for directing air across a turbine rotor, said turbine rotor being driven to rotate by the air, and drive a turbine shaft, said turbine shaft driving a sun gear;a plurality of planet gears driven by said sun gear;said plurality of planet gears engaged to drive a ring gear;said planet gears including a bearing within an inner peripheral bore in said planet gears, and a planet shaft in each said planet gear supported within said bearing, said planet shaft extending along a central axis;said planet gears including a surface hardened treatment at an inner peripheral bore which rides on said bearing, and said planet gear including a first part having a first set of gear teeth at a first axial location, and having a gear shaft extending axially away from said first set of gear teeth, a second part interference fit on said first part, said second part having a second set of gear teeth, and said second part being mounted on said gear shaft of said first part, and an outer diameter of said first part at said gear shaft being selected to be significantly larger than an inner diameter of a cylindrical portion of said second part which is interference fit on said gear shaft, with a ratio of said outer diameter of said first part to said inner diameter of said second part being between 1.0005 and 1.0100;wherein said second part has a chamber on an inner end of said cylindrical portion which is adjacent to said first set of gear teeth;wherein a cutout portion is provided on said first gear part between said outer diameter and said first set of gear teeth;wherein said cutout portion has a chamber formed between said outer diameter and said gear teeth; andwherein said inner end of said second part abuts a root of said first set of gear teeth. 4. A method of installing a planet gear within an air turbine starter comprising the steps of: inserting a planet gear onto mounting bearings on an outer periphery of a support portion of a planet shaft;wherein said planet gear includes a first part having a first set of gear teeth at a first axial location, and having a gear shaft extending axially away from said first set of gear teeth, a second part interference fit on said first part, said second part having a second set of gear teeth, and said second part being mounted on said gear shaft of said first part, and an outer diameter of said first part at said gear shaft being selected to be significantly larger than an inner diameter of a cylindrical portion of said first part which is interference fit on said gear shaft, with a ratio of said outer diameter of said first part to said inner diameter of said second part being between 1.0005 and 1.0100;wherein said second part has a chamber on an inner end of said cylindrical portion which is adjacent to said first set of gear teeth;wherein a cutout portion is provided on said first gear part between said outer diameter and said first set of gear teeth;wherein said cutout portion has a chamber formed between said outer diameter and said gear teeth; andwherein said inner end of said second part abuts an end face of said first part.