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).
Various change-speed gearbox schemes, categorized by their effect on ease of gear change and operational silence.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan048 | |
| Date | 25th March 1929 | |
| FROM DA.{Bernard Day - Chassis Design} Copy to HS.{Lord Ernest Hives - Chair} DA{Bernard Day - Chassis Design}1/M25.3.29. CHANGE SPEED GEARBOXES: Handwritten notes: X.523 / X2061 Mr. Hardy and I have gone through the gearbox situation, and report as follows: Two objects are being sought, viz: ease of change, and silence in operation. Very few schemes being tried give both, though we think both are necessary, because if the gear is easy to get into it will be used, and silence will be needed. The following is a list of the devices being adopted or tried by different people, or which seem to be possible: (A) THOSE FACILITATING CHANGING ONLY. (1) Various freewheel devices at the back of gearbox. (2) Freewheel in the sideshaft (RR. only.) (3) A coupling such as the Salerni coupling which is released for purposes of changing only, and locked up when synchronised. (4) The synchro-mesh - (Cadillac.) (B) THOSE GIVING SILENCE ONLY. (5) Internal mesh 3rd. speed with dogs - (Graham Paige: several alternative arrangements.) (6) Helical 3rd. speed with dogs - (Panhard: used as a separate unit by Mercedes & Voisin.) (7) Epicyclic 3rd. with dogs. (C) THOSE GIVING EASE OF CHANGE WITH A CHANCE OF INCREASED SILENCE. (8) Epicyclic 3rd. with brake operation (RR. proposal.) (9) The synchro-mesh with helical 3rd. speed. } This proposal (10) Internal mesh 3rd. with synchro-mesh attachment. } is not being used anywhere we believe. (11) Epicyclic 3rd. with synchro-mesh attachment. } (12) Complete epicylic box - (Armstrong-Whitworth.) Of those in Class C, only (12) is being used. Some of the others appear to present possibilities of an original arrangement being arrived at. (1) | ||