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 Messrs. North & Sons Ltd. regarding the incorrect calibration of a Watford Speedometer.
| Identifier | ExFiles\Box 165\4\ img193 | |
| Date | 1st July 1933 | |
| x6129. Ha/Wst.3/MA. July 1st., 1933. Messrs. North & Sons Ltd., Whipperdell Road, Watford. Watford Speedometer. Dear Sir, We do not seem to be getting much satisfaction with regard to the correct calibration of the model speedometer we are now testing. When it was first sent to us the revs per mile figure was 755 and we returned it to you for this figure to be altered to 797. We received this speedometer back again calibrated to 790 revs per mile. We should not mind this slight discrepancy of the rev per mile figure but we find that the speedometer reads as high as 12% fast at 90 miles per hour, whereas we only required it to be 6% fast. Also when we are driving it at our correct speed of 797 miles per hour the speedometer will read even slightly faster. We are afraid we must return this speedometer again to you for more correct calibration and we shall be glad if you will execute this work for us with the minimum possible delay. We require the instrument when driven at 797 revs per mile, i.e. 797 RPM. at 60 miles per hour to be 5 per cent fast rising to 6½% fast at 100 miles per hour. Yours faithfully, FOR ROLLS-ROYCE LIMITED. | ||