GB614402A - Improvements in or relating to power transmitting systems, particularly for aircraft - Google Patents

Abstract

614,402. Change-speed gearing; clutches. UNITED AIRCRAFT CORPORATION. Aug. 22 1945, No. 21539. Convention date, Nov. 3, 1944. [Class 80 (ii)] [Also in Group XXXIII] In a change-speed gear comprising a sun gear connected to the driving or driven member, a planet carrier connected to the other member and an annulus gear selectively connectable to the sun gear, a coupling having resiliently connected members is included, such coupling being operable upon a predetermined reduction of torque to release the connection between the sun and ring gears. In an all-wing, low aspect ratio aeroplane, the engines 38, 40, which have the same direction of rotation, are mounted inboard of the propellers 30, 32 having opposite directions of rotation and drive the latter through a system of transverse shafts 58, 60, 64 and bevel gears. The drive from the engines to the bevel gears 50, 52 is transmitted through resilient couplings 46, 48 and two-speed gears 42, 44. Torque reversal responsive relay mechanism is provided to disconnect the drive in the event of failure of one engine. Engine shaft 70 has splined to its forward end a disc 72, connected by resilient material 78, 80 and the plate 82 to a disc 76 splined at its centre to a planet carrier 94 freely rotatable about the hub 108 of a sun gear 106 splined at 109 to the driven shaft 90. Planet gears 100 mesh with the teeth 116 of an annulus gear 112 which is also freely rotatable about the hub 108. Annular clutch plates 124, 126 of a hydraulically-actuated friction clutch A engage with the extended teeth 106, 116 so that pressure in the cylinder 128 moves a piston 130 to engage the clutch and so lock the annulus 112 to the sun gear 106, the torque being shared between the clutch A and the planets 100. A second similar clutch B brakes the annulus 112 to the casing 151 to provide increased speed of the shaft 90. The shaft 90 provides a drive for a bevel gear 50 driving the transverse shafts 58, 64 which rotate in opposite directions. In the event of failure of one engine, the reversed torque on the resilient coupling 46 causes tooth 182 to be engaged by the recess 184 to rock the shaft 178 which, by rack and pinion 204, 202 and screw and nut 190, 194, move the bolt 192 longitudinally to operate a switch 198 which causes the release of both clutches A and B to free the shaft 70 from the shaft 90. This reversed torque mechanism is described and claimed in Specification 614,403.