Patent GB-1228749-A (GB)
IPC: F16H61/662
Filed: 1967-10-10
Abstract: 1,228,749. Variable - ratio gearing. ENGLISH ELECTRIC CO. Ltd. 9 Oct., 1968 [10 Oct., 1967], No. 46319/67. Heading F2D. In a variable speed transmission comprising series-connected continuously - variable - speed and planetary gear units, two rotary elements of the latter being arranged to condition the transmission for first low speed and second high speed regimes, as described in Specification 1,078,791, the two elements normally rotate in opposite directions, slowing down and reversal of either element operating a change-over device for initiating the introduction of the other regime. Transmission details (Fig. 1).-As shown the transmission consists of an engine drive shaft 7, planetary coupling 5, continuously variable friction gear unit 4, planetary gear unit 6 and output shaft 9. The friction gear unit is of the toric disc and roller type as described in Specification 1,133,265, consisting of two sets of rollers 18 mounted between toric discs 12, 14, 16, the angular setting of the rollers and axial pressure loading of the discs being controlled by an hydraulic servo unit 40. The planetary unit 6 consists of three interconnected threeelement trains, of which the sun pinion 10 of the first train is integral with the friction gear output casing 8, the sun pinion 56 of the second train is integral with the friction unit input shaft 2, while the planet carrier 50 of the third train is coupled to the output shaft 9. The first planet carrier 44 and final sun pinion 72 are controllable by brakes BH, BL operated by hydraulic servo units 66, 70 through a changeover mechanism 100 and rod 106. Control system (Fig. 2).-Pressure liquid for the system is supplied by input and output driven pumps 86, 88. The selector valve 84 is operated by a hand lever 80, the regime control valve 98 is connected to change-over rod 106 by a bell crank 108, while the governor valve 112 is jointly controlled by a centrifugal governor 126 and the throttle pedal 148. Pipelines 123, 160 are connected to the friction gear servo 40 and further connections are made to the brake servos 66, 70. A connection 184 is made to a ratio limiting valve 180 for the friction gear unit 4. Regime change-over mechanism (Fig. 7).-The change-over rod 106 is connected by a rod 300 and bell crank 301 to a toggle link 304 loaded by a spring 308 and operated by one or more abutments 314 pivotally mounted on the peripheries of rotary discs of brakes BL and BH. Each member 314 is spring loaded and so arranged that when disc BL or BH is rotating normally (arrow 302) it does not contact a rotary latch 316 loaded by a spring 320, but when the disc slows down and begins to reverse the nose portion 336 of member 314 is moved outwardly to engage the latch 316 which operates to reverse the setting of toggle link 304, so that change-over rod 106 is moved to reverse the setting of regime control valve 98. Operation.-For the forward low speed regime (Fig. 2) pressure liquid to friction servo 40 is supplied through line 123, servo 70 of brake BL being rendered effective to lock the final planet carrier 50 of planet gear 6, while servo 66 of brake BH is inoperative. Operation of governor valve 112 modulates the pressure in line 123 to vary the ratio setting of friction gear unit 4. For the high speed regime (Fig. 3, not shown), change-over rod 106 is operated to reverse the setting of valve 98 and thus reverse the pressure supply to brake servos 66, 70, to engage brake BH and thus lock the first sun pinion 10 of gear unit 6. The pressure supply to friction servo 40 is also reversed from line 126 to line 160. In this setting pressure liquid is fed to a servo piston 170 positioning a bell crank 164 which with links 174, 176 may be operated by the selector valve rod 194 to set the friction gear unit at a low ratio for engine braking. For reverse drive (Fig. 4, not shown), valve 98 and brakes BL, BH are set as for the forward low speed regime and pressure liquid to friction servo 40 is supplied through pipeline 160 by changing the setting of selector valve 84.