# US 2015/0176484 A1 · Geared turbofan with a gearbox aft of a fan drive turbine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0176484 A1 - Document ID: US20150176484A1 - Status: Published application - Kind: A1 - Application number: 14/162,810 - Filed: 2014-01-24 - Published: 2015-06-25 - Earliest claimed: 2013-12-23 - Assignees: United Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Frederick M. SCHWARZ; Gabriel L. SUCIU - Web page: https://patentgrep.com/patent/US20150176484A1 ## CPC - F02C 3/107: with two or more rotors connected by power transmission - 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) - F02K 3/06: with front fan - F05D 2260/4031: as in toothed 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) - F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A gas turbine engine according to an example of the present disclosure includes a drive turbine configured to drive a fan section, a speed change mechanism connected to the drive turbine and located aft of the drive turbine and aft of the fan. An output of the speed change mechanism connects to the fan. ## Claims ### Claim 1 A gas turbine engine comprising: a drive turbine configured to drive a fan section; and a speed change mechanism connected to the drive turbine and located aft of the drive turbine and aft of the fan, an output of the speed change mechanism connected to the fan, wherein the drive turbine is a fixed stator turbine and the fixed stator is located axially between a pair of turbine stages. ### Claim 2 (depends on 1) The gas turbine engine of claim 1 wherein the speed change mechanism is an epicyclical gearbox. ### Claim 3 (depends on 2) The gas turbine engine of claim 2 wherein a turbine drive shaft connects the drive turbine to a sun gear of the epicyclical gearbox. ### Claim 4 (depends on 3) The gas turbine engine of claim 3 including a connector attaching an output of the epicyclic gearbox to an inner shaft. ### Claim 5 (depends on 4) The gas turbine engine of claim 4, wherein the output of the epicyclic gearbox is a ring gear. ### Claim 6 (depends on 4) The gas turbine engine of claim 4, wherein the output of the epicyclic gearbox is a planetary carrier. ### Claim 7 (depends on 4) The gas turbine engine of claim 4 wherein the inner shaft extends through the sun gear. ### Claim 8 (depends on 1) The gas turbine engine of claim 1 wherein the speed change mechanism is a planetary gear system. ### Claim 9 (depends on 1) The gas turbine engine of claim 1 wherein the speed change mechanism is a star gear system. ### Claim 10 (depends on 1) The gas turbine engine of claim 1 wherein the speed change mechanism is located immediately aft of the drive turbine. ### Claim 11 (depends on 1) The gas turbine engine of claim 1 wherein the fan section and a low pressure compressor are attached to an inner shaft. ### Claim 12 (depends on 1) The gas turbine engine of claim 1 including a first compressor immediately aft of the fan section and immediately upstream of the combustor section. ### Claim 13 (depends on 1) The gas turbine engine of claim 1 includes a high pressure turbine and an intermediate turbine. ### Claim 14 (depends on 13) The gas turbine engine of claim 13 wherein the high pressure turbine is axially upstream of the intermediate turbine. ### Claim 15 (depends on 13) The gas turbine engine of claim 13 including a low pressure compressor and a high pressure compressor, wherein the low pressure compressor is connected with the intermediate turbine and the high pressure compressor is connected with the high pressure turbine. ### Claim 16 (depends on 13) The gas turbine engine of claim 13 wherein the gas turbine engine is a three spool gas turbine engine. ### Claim 17 (canceled) ### Claim 18 A method of operating a gas turbine engine comprising: rotating a fan drive turbine at a first rotational speed, wherein the fan drive turbine is a fixed stator turbine and the fixed stator is located axially between a pair of turbine stages; reducing the first rotational speed to a second rotational speed using a speed change mechanism positioned axially downstream of the fan drive turbine; and rotating a fan positioned upstream of the fan drive turbine and the speed change mechanism at the second rotational speed. ### Claim 19 (depends on 18) The method of claim 18 wherein the speed change mechanism is an epicyclical gearbox. ### Claim 20 (depends on 18) The method of claim 18 including rotating a compressor at the second rotational speed output. ### Claim 21 (depends on 18) The method of claim 18 including rotating only the fan at the second rotational speed. ### Claim 22 (depends on 18) The method of claim 18 wherein the gas turbine engine is a three spool gas turbine engine. ### Claim 23 (canceled) ### Claim 24 (depends on 18) The method of claim 18 wherein the speed change mechanism is a star gear system. ### Claim 25 A gas turbine engine comprising: a drive turbine configured to drive a fan section; and a speed change mechanism connected to the drive turbine and located aft of the drive turbine and aft of the fan, an output of the speed change mechanism connected to the fan wherein the speed change mechanism is a star gear system. ### Claim 26 (depends on 25) The gas turbine engine of claim 25, wherein the fan drive turbine is a fixed stator turbine and the fixed stator is located axially between a pair of turbine stages.