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).
Analysis of various gearbox and clutch systems, comparing Armstrong-Siddeley, a proposed Epicyclic design, and a Chrysler spool gear.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan074 | |
| Date | 14th April 1930 | |
| 2. DALL/N.14.4.30 Cont'd.{John DeLooze - Company Secretary} This is one more position than provided by Messrs. Armstrong-Siddeley viz "Coast". In this position the dog clutch is not withdrawn, so that the engine can be restarted without difficulty on moving into one of the gear positions, and operating the main clutch. At "stop" the relay withdraws the dog clutch into neutral, and at "reverse" puts it into the "reverse" jaws. In all the forward speeds the dog clutch remains in the forward jaws. The exact relay device is not specified, but the one in mind is an oil pressure arrangement operated by a special pump driven both by the engine and the car, probably with an accumulator to provide quick action. (3) is a suggested modification of the "Epicyclic 3rd. speed" box recently designed. The advantages claimed are that the engine can be restarted at any time by moving into Top or 3rd. speed, and therefore a salerni coupling of the simplest type i.e. merely a baulk ring without re-engaging devices, can be used on the 2nd. and 1st.speed. The objection hitherto has been that the sun wheel is revolved at a high speed when idling. It is now suggested that this can be overcome by holding out the main clutch when in neutral, either by a mechanical stop, or by the relay. The epicyclic clutch and brake are of the simple and light type already designed, and the two lower gears are obtained by conventional means with an easy change. Last week we tried a new Chrysler with a spool gear and stepped dog clutches for Top and 3rd. The gear could be changed with certainty at any speed, by simply withdrawing the main clutch and pushing straight in without double-clutching, or any art. The result was a curious "tinkle" much less than the noise which would have resulted from such a change with an ordinary gear box, and not we should think at all objectionable; but of course there must be mechanical shock increasing with the inertia of the parts. The spool gears were not quiet, not so quiet as our spur gears. (Incidentally the engine had bad torque reaction at low speeds, and brakes and steering were poor). We think it is a definite objection that the 2nd. and 1st. speeds are an ordinary change. Continued. | ||