GB831661A - Epicyclic power transmission mechanisms - Google Patents

Abstract

831,661. Variable-speed gear. WICKMAN, A. C. April 29, 1958 [May 10, 1957; May 20, 1957], Nos. 14888/57 and 15892/57. Class 80 (2). [Also in Group XXXIV] The reaction sun-gear 4, Fig. 1, of a changeratio planetary gear is either held stationary by supplying liquid under pressure to servomotor means 16 to engage a brake disc 12 having a frusto - conical friction surface 13 with a surrounding casing 15, or is alternatively clutched to a driving-shaft 3 by supplying liquid under pressure to more powerful servomotor means 24 which slide a clutch disc 21 having a frusto-conical friction surface 22 axially into engagement with the inner rim of the brake disc 12, continued rightward movement of the clutch disc 21 then disengaging the brake 12 so that the sun gear rotates with the driving shaft. In the form shown, the brake-engaging servomotor comprises pistons 16 in cylinders 17 in the casing 15, acting through a thrust-plate 18 connected to the brake disc by a bearing 19, and the clutch-engaging brake-disengaging servomotor comprises similar, but larger, pistons 24 in cylinders 25 acting through a thrust-plate 26 and a bearing 27. The servomotors work against the bias of springs 20, 28. Alternatively, the servo pistons 16, 24 can be of the same size, the pressure of the liquid supplied to the clutch engaging servo being greater than the pressure of the liquid supplied to the brake engaging servo. The planetary gear comprises a sun-gear 2 integral with the driving-shaft 3 and meshing stepped planet pinions 6 in turn meshing planet pinions 7 meshing the reaction sun-gear 4, a carrier 8 supporting the planet pinions and being fast with a driven shaft 9. A ring gear 10 meshed by the planet pinions 7 can be stationed by a band brake 11. In one modification, Fig. 2 (not shown), the clutchbrake combination controls a simple sun gearplanet pinion-ring gear two-ratio gear, the brake disc 12 sliding upon a sleeve fast with the sun gear and the clutch disc 21 sliding upon a sleeve fast with the ring gear, while in another, similar modification. Fig. 3 (not shown), the clutch disc 21 slides upon the driven shaft. In another form, the brake disc 12, Fig. 4, is moved to engage the casing 15 when liquid under pressure is admitted to a ring-shaped cylinder 31 containing a ring piston 32 acting through a roller thrust-bearing 35, and the clutch disc 21 is engaged with the brake disc 12 when liquid under pressure is admitted to a similar ring- shaped cylinder 36 containing a piston 37.