Patent GB-1241758-A (GB)
Title: Improvements in or relating to power transmission systems providing changes of gear ratio
Inventor: ELLIS FREDERICK EDWARD
IPC: F16H61/02
Filed: 1969-04-24
Abstract: 1,241,758. Holding-means for gear-train elements; change-speed gear. AUTOMOTIVE PRODUCTS CO. Ltd. 9 April, 1970 [24 April, 1969], No. 20958/69. Heading F2D. The invention relates to a speed reduction gear train of the kind comprising bevel gear clusters 12, Fig. 1, mounted on a carrier 11, the axes of the clusters lying in planes radiating from an axis about which the carrier is rotatable, and each of the clusters comprising two bevel pinions 13, 14, rotatable together as one, the bevel pinions meshing with other bevel gears 17, 25 and 18, 26 respectively, rotatable about the same axis as is the carrier, and two, namely 17, 18, of the "other bevel gears" being selectively drivable by the engine of the vehicle in which the gear train is mounted to act as input members. The invention provides holding means for use in association with an element, e.g. 26, 31, of a gear train of the above kind, comprising a toothed ring 32 (see also Fig. 2) constrained at all times against rotational movement in at least one direction relative to the element 26, 31 of the gear train, and a radially-slidable toothed element 36 capable of being selectively positioned so as to engage, or to be out of engagement with, the teeth of the toothed ring 32. Preferably the toothed element 36 is urged by a spring 39, Fig. 2, in the engaging direction, and by fluid pressure applied to the annular area 41 of the element head 42 in the disengaging direction. Preferably the toothed ring 32 is coupled to the gear element 26, 31, through a one-way clutch 33, comprising members 34 in a cage 35, so that gear element 26, 31, is rotatable in one direction when toothed ring 32 is held against rotation. As shown, the gear train includes an output shaft 10 on which is fixedly mounted the carrier 11, Fig. 1, and around which are located sleeves 15, 16 carrying respectively the driving bevel gears 17, 18. An input sleeve 19 also surrounding the shaft 10 is integral with the driving member of plate-type friction clutch 21, and has mounted for rotation therewith the driving member of friction clutch 22. These clutches, when engaged, drive respectively the bevel gears 17, 18, the driven member of clutch 22 having a drum surface 23 co-operating with a brake band 24 for holding it, and consequently bevel gear 18, against rotation. Bevel gear 25 is rotatable on shaft 10 and is integral with a sleeve 29 keyed to a drum 28 co-operating with a brake band 27; bevel gear 26, integral with ring 31, is rotatable on sleeve 29. The gear train provides four forward speeds and a reverse drive. The first forward speed is obtained by engaging clutch 21 while plunger 36 is inward, so bevel gear 17 causes clusters 12 to roll around bevel gear 26, causing carrier 11 and hence output shaft 10 to rotate. Reaction on bevel gear 26 is taken by one-way clutch 33 and plunger 36. The next higher forward speed is obtained by engaging brake band 27, keeping clutch 21 engaged and plunger 36 inward. The pinion clusters then roll around bevel gear 25, causing bevel gear 26 to rotate in the same direction as carrier 11, such rotation of gear 26 being permitted by one-way clutch 33, although ring 32 is held against rotation. The next higher forward speed is obtained by releasing clutch 21 and engaging clutch 22, keeping brake 27 engaged. Direct drive is obtained by engaging both clutches 21, 22, so that the carrier and the bevel pinion clusters rotate bodily, bevel gear 26 being allowed to rotate as before by oneway clutch 33 while plunger 36 remains inward. For reverse drive, bevel gear 17 is driven through clutch 21 and bevel gear 18 is held against rotation by brake 24, so that the bevel pinion clusters 12 roll around bevel gear 18, causing carrier 11 to rotate in the direction opposite to that for forward drive. Since rotation of carrier 11 in this direction is accompanied by rotation of bevel gear 26 in the same direction, plunger 36 must be moved outward to allow ring 32 to rotate. As an alternative, bevel gear 26 may be the output member of the gear train, bevel gears 17 and 25 being the driving gears. In that case toothed ring 32 would be formed on or fixed to carrier 11, and would be engageable with a plunger, as previously described, the positions of the plunger for the various speeds not being necessarily the same as described above.