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).
Relative merits of synchromesh and epicyclic gear systems.
| Identifier | ExFiles\Box 15\5\ Scan266 | |
| Date | 26th February 1932 | |
| HS.{Lord Ernest Hives - Chair} DA{Bernard Day - Chassis Design}/HDY.{William Hardy} } FROM R.{Sir Henry Royce} (At Le CanadelHenry Royce's French residence). X7310 C. to SG.{Arthur F. Sidgreaves - MD} MOR. BY.{R.W. Bailey - Chief Engineer} C. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} C. to Mr. CLAREMONT. CHANGE GEAR. I thank HS.{Lord Ernest Hives - Chair} for his memo. on the above. I quite agree that synchro mesh as being made is better than our epicyclic double top. For some time I have not intended to recommend making the epicyclic gear as drawn, but thought it worth while to finish it to the testing state. Our experience is shewing us a feature that we did not fully realise - i.e. the difficulty of avoiding jerking passengers by the car over-running the engine with all easy change gears. I do not think that the extra acceleration would worry us - i.e. as changing up, but when changing down the car is very likely to be running too fast for the engine, and one can get violent retarding, followed by vigourour low gear acceleration. The practice of double clutching, and also the Salerni coupling, seems to avoid this, and one thinks all other schemes would, with careless or poor drivers, occasionally give this effect. Two or three schemes have passed through my mind to make this less; (it would seem to be very much less with free-wheeling cars.) Some long time ago I concluded that if the synchro mesh did not fill the requirements then there seems nothing less than full epicyclic 4 speed and reverse. I have a very good gear train for either 3 or 4 speed and reverse which has not many wheels, and has the minimum of stress and brake requirements for the HP. (torque). We shall try to get a provisional patent for this scheme, and perhaps keep it moving in case synchro mesh is not good enough. When we started on double top there seemed several specimens that were thought to be good even by ourselves, but I am quite content for my own use with synchro mesh, and outside the Lanchester/Wilson gear there seems nothing better, and we had thought that this latter was not practical for big HPs.{Horace Percy Smith - Experimental Factory Mgr} and over seas work, but it may prove to be unfounded. Sent from WW. X.7310 X.7360 | ||