US 11,852,081 B2
Gearboxes for aircraft gas turbine engines
Mark Spruce, Derby (GB)
Assigned to ROLLS-ROYCE plc, London (GB)
Filed by ROLLS-ROYCE PLC, London (GB)
Filed on Nov. 15, 2022, as Appl. No. 17/987,338.
Application 17/987,338 is a continuation of application No. 17/827,214, filed on May 27, 2022, granted, now 11,542,873.
Application 17/827,214 is a continuation of application No. 17/197,311, filed on Mar. 10, 2021, granted, now 11,371,440, issued on Jun. 28, 2022.
Claims priority of application No. 2005033 (GB), filed on Apr. 6, 2020.
Prior Publication US 2023/0075036 A1, Mar. 9, 2023
Int. Cl. F02C 7/36 (2006.01); F02C 7/06 (2006.01)
CPC F02C 7/36 (2013.01) [F02C 7/06 (2013.01); F05D 2220/36 (2013.01); F05D 2260/40311 (2013.01); F05D 2260/98 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A gearbox for an aircraft gas turbine engine, the gearbox comprising:
a sun gear;
a plurality of planet gears surrounding and engaged with the sun gear; and
a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin,
wherein a ratio of a length, L, of the internal and external sliding surfaces to a diameter, D, of the journal bearing is between around 1.1 and 1.4 and,
wherein the journal bearing has a diametral clearance that is between 0.1% and 0.3%.