From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Description of the advantages of a new epicyclic gear and clutch arrangement over prior designs.
| Identifier | ExFiles\Box 147\4\ scan0201 | |
| Date | 15th May 1941 guessed | |
| selected direction. In prior gears of this type, the planet carrier of the differential gear corresponding to the gear 76 in Figure 3 is not locked when the vehicle is travelling straight so that this gear can act as a differential gear to permit the shafts driving the sprockets to turn at different speeds. The present arrangement has the following advantages over the known controlled-differential or controlled- epicyclic gears employing two slipping clutches, one for each direction of rotation :- a) Only one slipping clutch is employed and it is constantly driven from the engine at high speed so that the conditions are favourable for the dissipation of the heat generated by it slipping during a prolonged gradual turn. The difficulty of heat dissipation in this clutch will not be substantially greater than with either clutch of the prior arrangements since each must be designed to slip for long periods. b) The cone clutches which determine the direction of a turn are not required to slip so that the problem of heat dissipation will not normally arise with them. They can be lighter and cheaper than the second slipping clutch they replace. c) The cone clutches normally lock the shafts 27a and 27b so that these shafts and the bevel gearing 45, 47, 48 and 49 cannot act as a differential, as they would otherwise do, to permit one track to run faster than the other. An uncontrolled differential drive to the tracks permits either track to move at high speed if it loses its adhesion on the ground and this is undesirable in itself and because it results in parts of the driving 12. | ||