# US 2018/0320758 A1 · Gears having reduced roller element stresses and methods of manufacturing such gears > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0320758 A1 - Document ID: US20180320758A1 - Status: Published application - Kind: A1 - Application number: 15/426,130 - Filed: 2017-02-07 - Published: 2018-11-08 - Earliest claimed: 2017-02-07 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Darren Lee Hallman - Web page: https://patentgrep.com/patent/US20180320758A1 ## CPC - F16H 1/2836: {by allowing limited movement of the planet gears relative to the planet carrier or by using free floating planet gears} - F02C 7/36: Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H) - F03D 80/70: Bearing or lubricating arrangements - F16C 19/26: with a single row of rollers - F16C 33/34: Rollers; Needles - F16H 55/17: Toothed wheels (worm wheels F16H55/22; chain wheels F16H55/30) - F16H 57/08: of gearings with members having orbital motion - F05B 2240/50: Bearings - F05B 2260/40311: of the epicyclic, planetary or differential type - F05D 2260/40311: of the epicyclical, planetary or differential type - F16C 19/28: with two or more rows of rollers - F16C 2360/23: Gas turbine engines - F16C 2360/31: Wind motors - F16C 2361/61: Toothed gear systems, e.g. support of pinion shafts - F16H 2057/085: {Bearings for orbital gears} - Y02E 10/72: Wind turbines with rotation axis in wind direction - F16H: GEARING - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F03D: WIND MOTORS - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A gear having an axis of rotation includes a gear rim, with at least a portion of the gear rim configured to receive a load and define a loaded gear rim arc corresponding to the portion of the gear rim. A bearing pin extends axially through the gear rim, the gear rim and the bearing pin defining a roller element gap therebetween. The gear rim is configured to define a loaded roller element gap arc substantially concentric with the loaded gear rim arc, the loaded element gap arc having a loaded roller element gap arc length. The gear rim is further configured to retain a loaded bearing portion of the bearing within the portion of the roller element gap such that a loaded bearing portion length is in a range from and including about 75% to and including about 125% of the loaded roller element gap arc length. ## Claims ### Claim 1 A gear having an axis of rotation, said gear comprising: a gear rim, wherein at least a portion of said gear rim is configured to: receive a load; define a loaded gear rim arc corresponding to said at least a portion of said gear rim; and a bearing pin extending axially through said gear rim, said gear rim and said bearing pin defining a roller element gap therebetween; and a bearing disposed within said roller element gap, said bearing comprising a plurality of roller elements circumferentially disposed about said bearing pin, wherein said gear rim is configured to: define a loaded roller element gap arc substantially concentric with the loaded gear rim arc, the loaded roller element gap arc extending through a portion of the roller element gap and having a loaded roller element gap arc length; and retain a loaded bearing portion of said bearing within the portion of the roller element gap such that a loaded bearing portion length is in a first range from and including about 75% to and including about 125% of the loaded roller element gap arc length. ### Claim 2 (depends on 1) The gear in accordance with claim 1, wherein: each roller of said plurality of roller elements has a roller element diameter; and the loaded bearing portion length is defined as a sum of the roller element diameters of roller elements within the loaded bearing portion. ### Claim 3 (depends on 1) The gear in accordance with claim 1, wherein: each roller element of said plurality of roller elements has a roller element diameter; said bearing further comprises a bearing cage comprising a plurality of cage fingers, each cage finger of said plurality of cage fingers having a cage finger width and extending between adjacent roller elements of said plurality of roller elements; and the loaded bearing portion length is defined as a sum of the roller element diameters of roller elements retained within the loaded bearing portion plus the finger widths of cage fingers retained within the loaded bearing portion. ### Claim 4 (depends on 1) The gear in accordance with claim 1, wherein said each roller element of said plurality of roller elements has a roller element diameter and a roller element length, the roller element diameter and the roller element length defining a ratio in a second range from and including about 0.75 to and including about 2.0. ### Claim 5 (depends on 1) The gear in accordance with claim 1, wherein said plurality of roller elements is arranged in axially aligned roller element pairs. ### Claim 6 (depends on 5) The gear in accordance with claim 5, wherein: said each roller element of said plurality of roller elements has a roller element length; said gear rim has a gear rim length; and each axially aligned roller element pair of said plurality of axially aligned roller element pairs has a total roller pair length, the total roller pair length equal to a total length of roller elements in the axially aligned roller element pair, the gear rim length and the total roller pair length defining a ratio in a second range from and including about 0.5 to and including about 1.0. ### Claim 7 (depends on 1) The gear in accordance with claim 1, wherein said each roller element of said plurality of roller elements has a roller element length and said gear rim has a gear rim length, the roller element length and the gear rim length defining a ratio in a second range from and including about 0.5 to and including about 1.0. ### Claim 8 (depends on 1) The gear in accordance with claim 1, wherein said gear rim has a gear rim length and a gear pitch diameter defining a ratio in a second range from and including about 0.75 to and including about 2.0. ### Claim 9 (depends on 1) The gear in accordance with claim 1 further comprising a bearing comprising said plurality of roller elements, said bearing having a bearing pitch diameter, wherein said roller element diameter and said bearing pitch diameter define a ratio in a second range from and including about 0.08 to and including about 0.3. ### Claim 10 A gear assembly comprising: a sun gear; a ring gear; and a plurality of planet gears coupled to said ring gear and said sun gear, each planet gear of said plurality of planet gears having an axis of rotation, said gears comprising: a gear rim, wherein at least a portion of said gear rim is configured to: receive a load; and define a loaded gear rim arc corresponding to said at least a portion of said gear rim; and a bearing pin extending axially through said gear rim, said gear rim and said bearing pin defining a roller element gap therebetween; and a bearing disposed within said roller element gap, said bearing comprising a plurality of roller elements circumferentially disposed about said bearing pin, wherein said gear rim is configured to: define a loaded roller element gap arc substantially concentric with the loaded gear rim arc, the loaded roller element gap arc extending through a portion of the roller element gap and having a loaded roller element gap arc length; and retain a loaded bearing portion of said bearing within the portion of the roller element gap such that a loaded bearing portion length is in a first range from and including about 75% to and including about 125% of the loaded roller element gap arc length. ### Claim 11 (depends on 10) The gear assembly in accordance with claim 10, wherein: each roller of the plurality of roller elements has a roller element diameter; and the loaded bearing portion length is defined as a sum of the roller element diameters of roller elements within the loaded bearing portion. ### Claim 12 (depends on 10) The gear assembly in accordance with claim 10, wherein: each roller element of said plurality of roller elements has a roller element diameter; said bearing further comprises a bearing cage comprising a plurality of cage fingers, each cage finger of said plurality of cage fingers having a cage finger width and extending between adjacent roller elements of said plurality of roller elements; and the loaded bearing portion length is defined as a sum of the roller element diameters of roller elements retained within the loaded bearing portion plus the finger widths of cage fingers retained within the loaded bearing portion. ### Claim 13 (depends on 10) The gear assembly in accordance with claim 10, wherein said each roller element of said plurality of roller elements has a roller element diameter and a roller element length, the roller element diameter and the roller element length defining a ratio in a second range from and including about 0.75 to and including about 2.0. ### Claim 14 (depends on 10) The gear assembly in accordance with claim 10, wherein: said plurality of roller elements is arranged in axially aligned roller element pairs; said each roller element of said plurality of roller elements has a roller element length; said gear rim has a gear rim length; and each axially aligned roller element pair of said plurality of axially aligned roller element pairs has a total roller pair length, the total roller pair length equal to a total length of roller elements in the axially aligned roller element pair, the gear rim length and the total roller pair length defining a ratio in a second range from and including about 0.5 to and including about 1.0. ### Claim 15 (depends on 10) The gear assembly in accordance with claim 10, wherein said each roller element of said plurality of roller elements has a roller element length and said gear rim has a gear rim length, the roller element length and the gear rim length defining a ratio in a second range from and including about 0.5 to and including about 1.0. ### Claim 16 (depends on 10) The gear assembly in accordance with claim 10, wherein said gear rim has a gear rim length and a gear pitch diameter defining a ratio in a second range from and including about 0.75 to and including about 2.0. ### Claim 17 (depends on 10) The gear assembly in accordance with claim 10 further comprising a bearing comprising said plurality of roller elements, a bearing cage, and a plurality of cage spacers, said bearing having a bearing pitch diameter, wherein said roller element diameter and said bearing pitch diameter define a ratio in a second range from and including about 0.08 to and including about 0.3, and wherein said roller element diameter and said cage spacer width define a ration in a rage from and including about 0.01 to and including about 0.50. ### Claim 18 A method of manufacturing a gear having an axis of rotation, the gear including a bearing pin extending axially through the gear rim, the gear rim and the bearing pin defining a roller element gap therebetween, and a bearing disposed within the roller element gap, said method comprising: applying at least some load to the gear rim; identifying a loaded gear rim arc corresponding to a loaded portion of the gear rim when the load is applied to the gear rim; determining a loaded roller element gap arc extending through the roller element gap substantially concentric with the loaded gear rim arc, the loaded roller element gap arc having a roller element gap arc length; selecting the bearing such that, a loaded bearing portion of the bearing having a loaded bearing portion length is retained within the portion of the roller element gap, the loaded bearing portion length in a range from and including about 75% to and including about 125% of the loaded roller element gap arc length; and inserting the bearing into the roller element gap. ### Claim 19 (depends on 18) The method in accordance with claim 18, wherein: the bearing includes a plurality of roller elements, each roller element of the plurality of roller elements having a roller element diameter; and the loaded bearing portion length is defined as a sum of the roller element diameters of roller elements within the loaded bearing portion. ### Claim 20 (depends on 18) The method in accordance with claim 18, wherein: the bearing includes: a plurality of roller elements, each roller element of the plurality of roller elements having a roller element diameter; and a bearing cage including a plurality of cage fingers, each cage finger of the plurality of cage fingers having a cage finger width and extending between adjacent roller elements of the plurality of roller elements; and the loaded bearing portion length is defined as a sum of the roller element diameters of roller elements retained within the loaded bearing portion plus the finger widths of cage fingers retained within the loaded bearing portion.