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).
Gearbox technology, comparing dog-clutch shifts to synchromesh, discussing lubricants, and market adoption.
| Identifier | ExFiles\Box 19\3\ Scan137 | |
| Date | 11th January 1930 guessed | |
| - 7 - Shifting - On the subject of ease of shift, Neracher contends that a dog clutch shift with interrupted teeth using substantial clutches as shown is the most satisfactory device so far for an average driver. The General Motors "synchromesh" demands a certain hesitation in operation for satisfactory results, and in modern traffic there is no time for this hesitation. On the other hand the dog-clutches shift best "in a hurry", and are often used without declutching. With increase in speed and with increased size of the box there is audible shock (above say 40 mph. and especially in shifting down) but in practice there has been no damage. These boxes are being developed for city busses where they have been proved to save time enormously under heavy traffic conditions and have given no trouble from breakage so far. A clutch brake is not desirable with this box, for one reason that double-clutching down is not used, and extra oil-friction in the spools in shifting up gives some braking action. The efficiency of the box was not stated. No trouble occurs from oil heating, and a considerable fuel-saving is given by the higher axle ratio (which we can confirm from our own experience). Oil - Originally Mobiloil B was used, but slightly better results are given by Whitmores 70, containing lead-oleate. This was expected to cause lapping of the balls and rollers, but within 25,000 miles does not do so. It can be used safely in cold weather only by reason of the forcible feeding of oil to the inside of the spools. Availability for Test - If we should care to develop a box containing the general features either of the large or the small box shown in prints, all necessary information, tools for roller bearings, Fellows cutters, etc., are already in existence and an experimental box would therefore be inexpensive. Acceptance - Cannot give definite figures at the moment for cars in production on internal gear boxes. With Chrysler, Graham-Paige, Franklin, Stutz, etc. already producing these boxes, at least 50% of the industry are well ahead with experiments contemplating production. This list has recently come to include Packard (who have recently standardised a conventional 4 speed box of their own) and some of the General Motors companies. - continued - | ||