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).
Specification document detailing the transmission, clutch, gearbox, propeller shaft, and rear axle components.
| Identifier | ExFiles\Box 14\5\ Scan132 | |
| Date | 16th September 1929 guessed | |
| (3) The specification is much the same as at present. The engine sizes and description are the same, except the gearbox unit construction with engine, open propeller shaft, and rear axle carried by semi elliptic instead of cantilever springs. TRANSMISSION. This is the same as the 20HP. - by a single plate clutch to the 4 speed gearbox, through an open propeller shaft with two universal joints to the rear axle, of the hypoid type, the torque reaction of the latter being taken by the long rear springs. The whole is much lighter than the torque tube system. This keeps angular velocity of the shafts and wheels constant and independent of the vertical motion of the back axle. CLUTCH. The clutch includes our patented damper plate: the whole has been lightened and there have been some detail improvements. These include a more effective clutch stop, which, while being capable of a wider range of adjustment, is so improved in wearing area as to require little or no attention. GEARBOX. The 4 speed gearbox is part of a unit comprising also the engine and clutch. This has the advantage of saving weight and also of improving the weight distribution and as explained under the para. on suspension. The gearbox itself is lighter, smaller, and more compact, thus by the increased stiffness of its shaft facilitating silence. The reverse is now a sliding unit entirely out of gear when at rest. PROPELLER SHAFT. This is tubular and of very large diameter for lightness, and to avoid whirling. There is at each end a universal joint which has been specially designed to retain its oil for very long periods thus requiring the minimum of attention. Sliding is by an enclosed oil retaining joint at the forward end, where it is well protected from water and dirt. REAR AXLE. This is of the hypoid type, the advantages of which are :- extreme silence, great strength with low surface loading of the teeth, ensuring long life without attention, while the characteristic of the type, viz: the pinion offset below the crown wheel enables the floor of the body to be lowered, (impossible until the introduction of this gear). | ||