Patent GB-757511-A (GB)
Title: Improvements in or relating to branched drives
IPC: F16H3/66
Filed: 1953-09-02
Abstract: 757,511. Variable-speed gear. REICHENBAECHER, H. Sept. 2, 1953, No. 24259/53. Class 80(2). A split-torque drive for vehicles, lathes and cranes, comprises a planet gear having five or more elements, an input shaft 99, connected to one element. e.g. a planetcarrier 108, a variable-speed gear 109 between two of the other elements, e.g. suns 104, 117, and a clutch 111 for selectively connecting any one of the two or more remaining elements, e.g. a ring 103 and sun 105 to an output shaft 112, the arrangement being such that the entire control range of the variable gear 109 is passed over in alternately different directions for each position of the selector clutch 111 to vary the output speed in either one direction. The selector clutch 111 is selfsynchronized by the gear and hence allows shifts without interruption of power, as by positive clutches with no neutral, or cone or disc friction clutches mechanically, hydraulically, or electrically operated or electromagnetic or magnetic powder clutches. In the simplest form, Figs. 3 and 4, not shown, the planetary gear has four suns and no rings; a friction variable gear of the tilting-ball idler type directly connects one sun and the planet-carrier, whilst a double dog-clutch selectively connects the output shaft to either of the remaining suns, one directly, the other through a sun-ring fixed reducing train, the reaction brake of which slips on overload. The speed-range of the variable gear is 5 to 1, to 1 to 5, giving an overall ratio range, for specified wheel sizes, of 6 to 1. 1 to 1.5. in two stages of 6 to 1, to 2 to 1, using one clutch setting, and 2 to 1, to 1 to 1.5 using the other, the variable-gear being adjusted throughout its range in opposite directions for the two clutch settings, whereby at the shift point the changed elements are automatically synchronized and shift may be sudden with no neutral. Balk-rings may be used. Fig. 5 provides four definite dog-clutched speed steps, each covering the range of the variable gear 109 which is driven through a step-up gear to reduce its torque-share and hence its size. Double stepped planets on a carrier 108 on the input shaft 99, mesh suns 104, 105, and rings 101, 102. The sun 104 is connected to one element of the variable gear 109, the other element of which is driven by the ring 101 through a step-up gear comprising a fixed ring 119, input planet-carrier 107 and output sun 117. The sun 105 and ring 102 form alternative takeoff members clutchable selectively to a final output shaft 112 through two-ratio reducing gear-pairs 115, 113 and 116, 114, as follows. Splined to the two pinions 115, 116, and connected together for axial but not rotary movement, are two clutch dogs 115a, 116a, for mesh with dogs 111 on the sun 105 and ring 102 in four positions (no neutral). Position I clutches together the ring 102 and pinion 116 of lowest speed range; position II, shown, sun 105 and pinion 116 for second; position III, ring 102 and pinion 115 for third; and position IV, sun 105 and pinion 115 for fourth. The arrangement is such that, by the time the variable gear has been taken to its extreme positions in opposite directions for alternate steps, the clutches to be meshed for the next step are automatically synchronized, rendering further synchronizing devices unnecessary, although balk-rings are fitted. Bevel planetary gearing may alternatively be used, and input and output, shafts may be interchanged.