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).
The correct speedometer calibration for a 20 HP chassis owned by a Mr. Minchin.
| Identifier | ExFiles\Box 50\4\ Scan322 | |
| Date | 1st November 1929 | |
| X4208. EFC. BY/Cgh{W Clough}11/G.1.11.29. SPEEDOMETERS. With reference to EFC4/AD.31.10.29. and copies of your letters to Mr. Minchin in connection with the speedometer fitted to his last 20 HP. chassis, so far as we can make out the last chassis supplied to him was GFN.8 and was fitted with 5¼" section medium pressure tyres and a rear axle having a ratio of 12/50. Speedometers for similar chassis when fitted with 11/50 ratio axles were all calibrated for 740 revs. per mile, therefore the correct figure for Mr. Minchin's speedometer is 680. We cannot find from our records that we supplied the speedometer, therefore it would appear that Mr. Minchin obtained this himself. BY/Cgh.{W Clough} [STAMP: RECEIVED 1 NOV 1929] | ||