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).
Comparison of the merits of an epicyclic third gearbox versus a synchro-mesh gearbox.
| Identifier | ExFiles\Box 179\2\ img243 | |
| Date | 11th February 1932 guessed | |
| ORIGINAL To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Dor.{Mr Dorey} c. to Hr. Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} Hs.{Lord Ernest Hives - Chair}2/WJ.11.232. K7310 P.2 GEARBOX WITH EPICYCLIC THIRD. We have now got this gearbox working satisfactorily. It works as well as one can anticipate. We have overcome the slipping on third gear by increasing the strength of the spring. Now that we have arranged to brake so that it will stand up and not slip excessively, there is of course more jerking of the passengers if the change is made without consideration to the relative engine speeds and car speeds. Now that we have a successful synchro-mesh box we are in a position to compare the merits of these two schemes. The advantage of the Epicyclic box is the ease of operation, but we still feel the fact that it is so easy to operate will leave it open to abuse which will effect its reliability. The disadvantages of the Epicyclic third over the synchro-mesh, as we see them are :- (1) Considerable increase in cost. (2) Increase in weight. (3) Many more parts to wear and go wrong. As regards silence, the synchro-mesh box is more silent than the third speed epicyclic but we think it is possible with the same care and perhaps the use of Helical gears the Epicyclic could be made as quiet as the synchro mesh. This point, however, still remains to be proved. We have lately tried other cars fitted with the Wilson gearbox and fluid flywheel, and it is no use shutting our eyes to the fact that the combination of the Wilson gearbox with the fluid flywheel is by far the best solution of the easy change gear in use today. We believe the fluid flywheel adds tremendously to the reliability of the Wilson gearbox and makes the scheme very different to the original scheme when the orthodox clutch was in use. There are an increasing number of cars on the road with this scheme fitted, and it is also now being fitted to a lot of the London 'buses. In the past I have been rather dubious as regards the value to the customer of the complete easy change gearbox but I think the success of the Wilson gearbox and clutch should make us look ahead to what we shall have to offer to follow on the synchro-mesh box. An owner who has driven cars with a Wilson gearbox for a number of years would find it very difficult to adapt himself to the normal gearbox, because it would mean learning how to change gear. | ||