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).
The merits of three-speed versus four-speed semi-epicyclic gear arrangements.
| Identifier | ExFiles\Box 49\1\ Scan225 | |
| Date | 12th October 1920 | |
| Contd. -5- H18/C21 12.10.20. In my simple semi-epicyclic arrangement I get four speeds because I cannot help it. In this case the dis-advantages are nil, and the third speed will naturally be, and can be nearer to the top speed for reasons which are difficult to explain, but with the usualy change speed gear unless one has a fairly good drop in speed the change to the third would not give sufficient advantages. You will remember that your old "Mystery" with its three speed was better on the Dover Castle Hill than the four speed boxes, because the second on the "Mystery" was a slightly greater drop than the second to the third on other cars. For the time being I am proceeding with the schemes we have in hand, as I still consider they are the best we know at present, and I am sure buyers will be most pleased with the results obtained. R.{Sir Henry Royce} | ||