| 摘要 |
An aircraft (10) having turboprop propulsion has a plurality of gas turbine engines (11), each with a two stage reduction gearbox (30,41) with the engine output shaft (17,17A) inline with the propeller drive output shaft (19,51) to drive a propeller (12) in front of the engine in a tractor mode of propulsion. The input gear reduction stage (20) and output gear reduction stage (21) share a plurality layshafts (22,38) mounted in fixed circularly-spaced relation to each other about the axis of the output shafts in the mechanical housing in the aircraft. Each layshaft of said plurality of layshafts has a layshaft first end toward the rear, input end of the gearbox, and a layshaft second end toward the output, front end of the gearbox. The layshaft gears are arranged to avoid any net thrust loading of the layshafts. Spur (26) and double helical (27) are used in FIG. 4, while spur gears 37 and 48 are used in FIG. 6 with suitable helix settings to neutralize end thrust on layshaft 38. Cantilever layshaft input gear (37) mounting in rear bearings (39) enables it to share some layshaft output gear 48 load sharing with the front bearing (40). A torquemeter (61) is conveniently situated at the gearbox input end. The engine output gear (25,36) and gearbox output gear (28,49), and propeller (12) all have colinear rotational axes.
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