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).
Evaluation of different gearbox and transmission designs, including competitor analysis and historical development attempts.
| Identifier | ExFiles\Box 6\4\ 04-page290 | |
| Date | 3rd November 1930 guessed | |
| (2) applied to a 3 speed box, which is not ideal for present driving conditions which ask for a fairly low top and high third. This gear change is not available to us and I should not recommend its use if it were. Maybach, Voisin, Mercedes-Benz, and perhaps a few more, seem to be using an overspeed gear like our early indirect 4th, though by a more silent gear, but with the present very high engine speeds we do not wish the transmission to run faster than the engine (usually 1.3 times at least) and we consider this scheme defective although the details adopted by some makers have virtues. Then there is the older Panhard scheme which has not attracted much attention until lately, but is very safe and practical. This is the use of single helical side shaft and 3rd. speed gears always in mesh, and operated by jaw clutches. If skilfully made this makes a nearly silent 3rd., which, with a small ratio (as used in the spool gear) is not hard to change, and we are quite in agreement what this should be used unless we think better that will include another gear, or be more easily obtainable (i.e. steering column control.) Of our own attempts we have made several which are nearly good enough. Historically, we schemed about 1908, the freewheel type (our specimen was side shaft only) and this was greatly appreciated by the late Mr. E.A.Claremont and a few others, but we did not think it safe enough to adopt, and in reviewing the subject with even modern improvements we still think so - (originally only for ease of change, not for silence of gears.) Another still earlier attempt at something unorthodox was our indirect 4th. overspeed gear which we used for some time, but experience proved of insufficient value. After many attempts during the past 10 yrs. for complete epicyclic gears (which were shelved through other work and no scheme was forthcoming of sufficient merit to fix our attention) we patented a double top scheme of a single epicyclic for 3rd. (in front of an ordinary box) operated either by friction or positively. This scheme is our greatest hope, and after designing 2 other arrangements of complete epicyclic gears, (one partly by brakes and the other all positive by synchronising brakes and pawls or jaw clutches,) we are pushing forward our double top with 3 speed box/all possible despatch, and hope to complete with | ||