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).
Details on a proposed larger internal gear assembly, selector shift, axle ratios, and torque-equalized brakes.
| Identifier | ExFiles\Box 137\5\ scan0099 | |
| Date | 6th September 1930 guessed | |
| Oy-l - 2 - (3) Send you drawings of a larger internal gear assembly suitable for 350 lbs. feet torque with their suggestions (which may not interest you) for the use of improved materials as compared with their present practice on the "Imperial Eight" which has only about 300 lbs. feet. All this will be sent "on consignment". i.e. if the box doesn't interest you, or you get finished with it, send it back - no charge. Both schemes and the actual box will be fitted with the new "selector" shift which is a development of the Maybach clutch, similar to the Salerin coupling, but simpler in application. This means, that the dogs are backed off in a direction to prevent engagement until the speeds are synchronized and the shifting means is provided with a spring device which will prevent the non-engagement of the dogs from vibrating the hand of the driver. This appears to be the final answer to the objection of "thumping" engagements, particularly when shifting down on the internal gear box. It is similar to a free wheel in some respects, but much simpler. (See sketch). In applying this box to say the 25 HP, their recommendation for "ideal" results is as follows:- Raise the axle ratio from say 1 to 5 to 1 to 4 choosing the new ratio so that, when the engine power-curve is "written down" 10% to allow for average "lack of tune" after a year's use, the peak of the power curve lies on the curve of power required with a body of average wind-resistance. Supposing this "ideal" axle ratio turns out to be 1 to 4. Third gear will be .7 of this giving a virtual ratio of about 1 to 5.6 which is ideal for (American) city driving. Second gear is used for starting. Brakes The following will interest you. A brake has long been under development which is "torque equalized". I wrote you about this some years ago. The brakes on either end of the axle are so arranged, the anchorage pins being interconnected, so that neither of them can deliver more torque than the other. Hence, equal braking-lack of skidding, etc. This is developed for four-wheel applications. Now it is further developed as an automatic brake adjustment, so that the same mechanism which balances the torque also keeps the two brakes set up "on a torque-basis" (just as they would be adjusted by say a garage with a four-wheel Bendisc-Cowdray brake tester.) (Continued) | ||