GB870863A - Improvements relating to motor vehicle power transmissions - Google Patents

Abstract

870,863. Hydraulic transmission of power. FERGUSON RESEARCH Ltd., HARRY. June 3, 1959 [March 11, 1958], No. 7764/58. Class 69 (2). [Also in Group XXIV] An hydraulic variable-speed transmission for a motor vehicle comprises a torque converter having a casing 10 connected to the engine to rotate therewith, a turbine 12 connected to the driven parts of the transmission, and an impeller 11 releasably connected to the casing, means under the control of the driver being applicable to restrain the impeller against rotation whereby a braking effect is applied to the transmission. The turbine 12 is keyed to the output shaft 14 which extends through a sleeve 16 secured to a stationary gear-case 15 and connected to a reaction member 13 through a oneway free-wheel device 17. The impeller 11 is secured to the planet carrier 25 of an epicyclic gear having a sun-wheel 21 secured to a sleeve 26 and an annulus 22 secured to the casing 10. The gear is controlled by three clutches 31, 32, 33, clutch 31 connecting the impeller and planet carrier to the sun-wheel sleeve 26, clutch 32 connecting the sun-wheel sleeve to the stationary gear-case 15, and clutch 33 connecting the impeller and planet carrier to the gear-case. The clutches 31, 32 and 33 are operated by fluid presure supplied from a pump 34, 35 to an annular piston and cylinder 38, 39, an annular piston and cylinder 43, 44, and an annular piston and cylinder 47, 48 respectively, clutch 31 being engaged by springs 41, and clutches 32, 33 by the fluid pressure. The supply to the cylinders is controlled by a valve 102 having a spool 105 controlled by a solenoid operated by a switch on the steering column, and a spool 100 operated by a lever 86, 87 and a rod 76 controlled by a hand lever 60 which also serves to move a fork 60A to axially move a member 63 of a reversing gear to provide forward, neutral or reverse rotation of a final output shaft 56, notches 72, 73, 74 determining the lever positions. During normal drive, fluid from the pump 34, 35 to the inlet 106 of the valve is cut off from the. cylinders so that only clutch 31 is engaged by its springs and the impeller is connected to the sun-wheel sleeve 26 and rotates at the same speed as the casing 10 driven by the engine. Movement of the spool 105 from the position shown in Fig. 3 connects the supply to the cylinders 39, 44 to disengage the clutch 31 and engage clutch 32; the sun-wheel sleeve is thus freed from the planet carrier and impeller and locked to the stationary gear case, the ratio of the speed between the casing 10 and impeller being determined by the ratio of the gearing. A slight braking effect may be provided by this arrangement. When the valve spool 100 is moved inwardly by the control lever being moved into a guideway 71 or a notch 75, the fluid supply is connected to the cylinders 39 and 48 and clutches 31 and 32 are disengaged and clutch 33 engaged, the planet carrier and impeller being held against rotation so that the impeller acts as a brake. Specification 601,303 is referred to.