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 discussing the design and merits of a double top gear system.
| Identifier | ExFiles\Box 6\2\ 02-page161 | |
| Date | 17th April 1931 | |
| DA.{Bernard Day - Chassis Design} FROM R.{Sir Henry Royce} HS.{Lord Ernest Hives - Chair} (I HAD TO BUNDLE.) 1. to W. RCR. 2. to E.{Mr Elliott - Chief Engineer} HY.{Tom Haldenby - Plant Engineer} X523 RLW/17.4.31. DOUBLE TOP GEAR. X.523. X.7310. Mr. Lidsay's opinions and criticisms are premature. Our scheme of control will be sound as simple as anything and should be easier to work than Wilson because we do not have to work a heavy long stroke pedal. There should be no confusion in mix. It is only like many other double tops - Maybach, Mercedes, Voith. That the epicyclic is not silent need not worry us for the moment. It can be made so by correct teeth, by finer pitch, by making these finer pitch helical to a small degree, and if still not silent equal to an increased angle and perhaps wider. DA.{Bernard Day - Chassis Design} is quite right when he suggests much less angle down from original 6° to 3° with 8 teeth instead of 5. This should be put in hand. Clearances are usual etc. we seem much too small and springs unnecessarily stiff - good points easily altered. Naturally must be controls on steering column etc etc. should not be criticised for untidiness. The standard type of gearbox can be made to idle satisfactorily so that the same thing belonging to this combination should not give any greater trouble. A Salerni ring might be preferable to Maybach jaws. He promised me we could use these without paying any royalty.- i.e for the reputation. I do not think synchro-mesh suitable for anything but hand controlled gears. Our complete epicyclic gear should be quieter than any known gears because the rate of engagement is extremely low. There is a division to synchro-mesh and is meant for aids lever engagement. It may be thought that our double top might be carried in one in other gears than the purely simple double balanced helical as used by some German designers on electrical motor work, but so I think that we are doing is best. When idling we ought to be quite good when we have gears which have correct teeth that are not too tight. When on top we ought to be rather better than an ordinary box with 2 single helicals because the gears in our box idle, are always running relative to its. and running more slowly. We may find we have other disadvantages but as far as I know there is no reason why tests should give the results arrived at with less disadvantages. | ||