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).
Letter discussing the correct calibration for a speedometer on a 20 HP chassis.
| Identifier | ExFiles\Box 50\4\ Scan324 | |
| Date | 4th November 1929 | |
| X4308. EFC1/AD. 4th November, 1929. Mr. Minchin, Messrs. Peto & Radford, 50, Grosvenor Gardens, London, S.W.1. Dear Mr. Minchin, Speedometer. I have received your further letter of the 1st inst. I shall be interested to hear if you are pleased with the new reading. My enquiry to the Drawing Office has been answered as follows :- "With reference to EFC4/AD31.10.29. 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." You will see that we have no record of having supplied this instrument so that there will have been no check on its accuracy by our Test Dept. The instrument was as sealed by the makers but now the seals are broken. It will be useful to us if | ||