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).
Technical memorandum detailing modifications to a gearbox design, including pinions, clutches, and servo placement.
| Identifier | ExFiles\Box 104\4\ scan0202 | |
| Date | 4th September 1933 | |
| - 2 - HDY.{William Hardy}2/HP. 4.9.33. In order to save length in the box, the tops of the teeth of the 1st speed pinion are used to assist in the control of the sleeve for the 2nd speed S.M. clutch. As the pinion slides entirely out of the sleeve in 1st speed it is necessary to provide a slight lead in for the return of the pinion. When changing into first speed there will be resistance from the plungers and the relay cam which is unavoidable. We have reduced this to an amount that we consider to be unimportant by reducing the inclination of the plunger groove to 15º on the first speed side. We think that a smaller angle than 15º will give insufficient locational force in neutral on the sleeve. We have reduced the width of the S.M. cones from .625 to .500 as there appears never to be any appreciable wear on these. Roller bearings are used for the centre bearings and these, together with the rearmost bearing of the layshaft are of the Hoffmann F.{Mr Friese} type which require no retaining devices for their outer races. We suggest that the bushes for the reverse shaft should not be secured in place except by the press fit used. Provision has been made for a 20/25 servo. This is placed on the offside to avoid the long countershaft which was necessary.with unit construction. The servo bridge is turned end for end. This arrangement facilitates the provision of faces on the gearbox for the bridge brackets and will, we think, suit the brake rod layout. It will be noticed that the bridge brackets are on different halves of the box. Some provision may have to be made for variation of the centre distance of the bridge supports due to the gearbox casing jointing washers. HDY.{William Hardy} | ||