Gear ratio selection for the Goshawk back axle, concerning the crown wheel and pinion teeth count.
| Identifier | WestWitteringFiles\H\February1922\ Scan24 | |
| Date | 15th February 1922 | |
| To Ry. from R. {Sir Henry Royce} ORIGINAL c. to W. c. to H.S. c. to Mr. c. to H.S. ✓ c. to W. RECEIVED RE GOSHAWK(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) BACK AXLE. X4256 Referring to the back axle for the Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)), we notice a 60 tooth crown wheel has been adopted, which is rather a pity as it might have been 59 or 61, or some other prime number, which must be adopted if 12 or 15 tooth pinions are ever used. It will however be right for 13 teeth and 14 teeth in the pinion. The 13 tooth pinion is thought right for the covered cars such as limousines, etc. and "B" steering, and the 14 tooth pinion for open cars, and speed bodies, and "D" steering. I am very anxious not to under-gear this car as in any case the engine will run very fast, and we may be disappointed in the wearing qualities, and the difficulty of keeping parts such as ignition, etc, in a state of such exact condition, as to always act faultlessly at such high speeds. R. {Sir Henry Royce} | ||
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).