GB871399A - Improvements in or relating to speed changing mechanisms - Google Patents

Abstract

871,399. Variable-speed gear. SACCHI, G. Jan. 24, 1958 [Jan. 24, 1957], No. 2465/58. Class 80 (2). A steplessly variable ratio gear for motor vehicles comprises two wheels 20, 22 in peripheral frictional engagement at least one, e.g. 20 of the wheels being radially deformable to vary its effective diameter by varying the radial eccentricity of either wheel to vary the speed ratio between the wheels. Radial deformation is permitted by an external or internal pneumatic tyre, e.g. 21 in the wheel 20. In Fig. 4 (not shown), the wheels 20, 22 form final driving and driven members, eccentric movement of the wheel 22 being permitted by a double universal joint connecting it to the output shaft. In Fig. 5 (not shown), the wheel 22, similarly jointed to the output shaft, is a planet carried on a variable eccentric on the input shaft, and the wheel 20 is fixed. In Fig. 1 the variable gear is planetary and is connected with an invariable torque splitting- toothed planet gear. The variable gear comprises an outer drum 20 which may be held by a brake 30 releasable for use as a starting control and carries internally a pneumatic tyre 21, a coaxial input (or output) shaft 16 has a ratio selecting variable eccentric 17 (of the compound type, Fig. 2 (not shown)), freely carrying a planetary drum 22 engaging frictionally the tyre 21 and carrying internally a tyre 23, which frictionally engages an inner drum 24 free on the shaft 16. The shaft 16 and the drum 24 comprise two input (or output) members of the invariable epicyclic gear comprising an internal and external planet 35 carried eccentrically by the shaft 16, a sun 31 fast to the drum 24 and a ring gear 32 fast on the output (or input) shaft 33. In Fig. 3 (not shown, the invariable epicyclic gear comprises a sun fast on the input shaft, an output ring gear and a simple planet carrier connected through an invariable reversing gear to the friction drum 24 (Fig. 1). In Fig. 7 (not shown) the input shaft is connected to one side wheel of a bevel differential gear, the other side wheel being connected to the output shaft which carries the variable eccentric of the friction gear, whilst the planet carrier is connected through a two-stage reduction gear to the inner drum 24 (Fig. 1) of the friction gear. In Fig. 8, an input shaft 16 drives a sungear 70 which meshes a planet pinion 71 of stepped planets 71, 72, the planet carrier 74 of which is connected to the inner drum 24 of the friction gearing. A ring gear 73 is fixed to an output shaft 33 which carries fixed thereto the outer drum 20 of the friction gear. The intermediate drum 22 is freely rotatable on a stationary variable eccentric 75. Formulµ for the gear ratios are stated. Specifications 158,429 and 501,758 are referred to.