Gas turbine gearbox

Abstract

A method of manufacturing and/or providing a gearbox for rotating a propeller in a selected single one of a first and second direction is disclosed. The gearbox includes a many common components, selected irrespective of desired propeller direction, and a few unique components selected based on desired propeller direction. In one aspect the method includes casting a casing of the gearbox and machining the casing according to a selected configuration of the gear stages of the gearbox used to achieve direction of the propeller in the selected direction.

1 . A method of manufacturing a gearbox for rotating a propeller of a gas turbine engine in a selected single one of a first and second direction opposite each other, the method comprising the steps of: 
 casting a casing;    selecting single one of a first and second configuration corresponding to the selected single one of the first and second direction;    machining the casing according to the selected one of the first and second configuration;    partially inserting an input shaft and an output shaft within the casing;    providing in the casing a gear train adapted to drive the output shaft, a mating gear meshed with the gear train, an input pinion coupled to the input shaft, a multiple member gear, and a plurality of accessory drive gears each adapted to drive one accessory, at least one accessory drive gear being meshed with each member of the multiple member gear;    providing in the casing at least one element corresponding to the selected single one of the first and second configuration, the at least one element of the first configuration consisting in a first idler gear and an accessory pinion, and the at least one element of the second configuration consisting of a second idler gear; and    arranging an interaction between the input pinion, the mating gear, the multiple member gear and the at least one element according to the selected single one of the first and second configuration, the interaction of the first configuration consisting in meshing the input pinion with the mating gear, meshing the multiple member gear with the first idler gear, meshing the first idler gear with the accessory pinion, and coupling the accessory pinion with the input pinion, the interaction of the second configuration consisting in meshing the input pinion with the second idler gear, meshing the second idler gear with the mating gear, and coupling the multiple member gear with the mating gear.    
   
   
       2 . A method of providing a single-propeller turboprop engine, the method comprising: 
 providing a gas turbine; and    providing a reduction gearbox, the gearbox mounted to an output shaft of the gas turbine, the gearbox having an output propeller shaft and at least first and second gear stages coupled to one another, the first gear stage adjacent and coupled to the output shaft of the turbine, the second gear stage adjacent and coupled to the output propeller shaft, wherein the step of providing the reduction gearbox includes the steps of: 
 selecting a first gear stage configuration from a group consisting of a first gear set adapted to permit clockwise propeller operation and a second gear set adapted to permit counter-clockwise propeller operation;  
 providing a second gear stage configuration operable with both the first and second gear sets of the first gear stage;  
 selecting a desired direction of rotation for the propeller; and  
 selecting the first gear stage configuration corresponding to said desired direction of rotation.  
   
   
   
       3 . The method according to  claim 2 , wherein the method further comprises providing a casing for the reduction gearbox, including the steps of: 
 providing at least one casting; and    machining the casting to have a shape selected from the group consisting of a shape adapted to house the first gear set and a shape adapted to house the second gear set.