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 to a speedometer company requesting a calibration update for new tyre specifications.
| Identifier | ExFiles\Box 50\4\ Scan117 | |
| Date | 18th May 1927 | |
| EFC {E. Fowler Clarke - Electrical Engineer} COPY. C. Mailing Dept. BY {R.W. Bailey - Chief Engineer} /Cgh {W Clough} 18/H. 18.5.27. May 18th, 1927. Wednesday. The A. {Mr Adams} T. Speedometer Company, Ltd., 20, Avonmore Road, West Kensington, London. W.14. Dear Sirs, We are in receipt of your letter of the 17th inst. reference COB/H, and we wish to confirm the statement made by our Lillie Hall Depot that our 40/50 HP. chassis are now equipped with 33 x 6.75 balloon tyres, and apparently there has been some mistake that you have not been informed previously in regard to modifying the calibration of the speedometers. These instruments should now be calibrated for a speed of 745 revolutions per mile instead of 720 as previously, therefore will you please arrange to supply instruments suitable for this speed in future for our Phantom chassis when equipped with 33 x 6.75 balloon tyres. The speed quoted in the second paragraph of your letter is apparently wrong, and according to our information should read "739". Yours faithfully, [Handwritten calculation] Miles per hour at- standard speed of 600 R.P.M. = 36000 / revs per mile. 36000 / 745 = 48.3 TECHNICAL PRODUCTION ENGINEER. FOR ROLLS-ROYCE LIMITED. | ||