GB901314A - Improvements in or relating to variable-ratio gear transmissions - Google Patents

Abstract

901,314. Variable-speed gear. ROLLSROYCE Ltd. May 28, 1959 [July 25, 1958], No. 24108/58. Class 80 (2). A combined hydraulic and epicyclic variablespeed gear provides two reduced ratios, direct drive, over-drive and reverse, all the drive being transmitted through a fluid coupling for the reduced drives and reverse, and the torque being split for direct drive and overdrive. The planet carrier 20 of an input epicyclic train is directly driven by an input shaft 10, its ring gear 17 is fast with the pump 12 of an hydraulic coupling, and its sun gear 23 is selectively stationed by a band brake 27 and clutched to the planet carrier by a clutch 25. The turbine 13 of the coupling is fast with a sun gear 35 of an output epicyclic train having a planet carrier 32 fast with an output shaft 34 and a ring gear 28 selectively stationed by a brake 30 and clutched to the ring gear 17 of the input train by a clutch 31. A reverse train comprises a planet carrier 38 fast with the output shaft, a sun 37 fast with the ring gear 28 and a ring gear 40 stationable by a brake 42. For first gear, brake 30 and clutch 25 are applied, so that the input train is locked and drives the coupling 12, 13 which drives the output shaft at a reduced ratio through the output train. For second gear, brakes 27, 30 are applied, and the input train drives the coupling at a step-up ratio. For direct drive clutches 25, 31 are engaged and the drive is divided and then re-combined in the train 15. For over-drive brake 27 and clutch 31 are applied. For reverse brakes 27, 42 are applied. Neutral is obtainable by releasing all the brakes and disengaging both clutches.