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 from a supplier discussing the long-term accuracy and stability of speedometer instruments.
| Identifier | ExFiles\Box 50\4\ Scan136 | |
| Date | 18th August 1927 | |
| CONTRACTORS TO THE WAR OFFICE THE ROYAL AIR FORCE AND LEADING MANUFACTURERS. V4308 A.T. SPEEDOMETER Co. LTD. Trade Mark. DIRECTORS: F. {Mr Friese} T. FISHER, H. {Arthur M. Hanbury - Head Complaints} O. {Mr Oldham} BOOTH, S. D. {John DeLooze - Company Secretary} McKELLEN, Telephone: Western 1422. Telegrams: Aytespeedo-Hammer, London. Your Ref. GFC5/T. Our Ref. GOB/W... [Left Column Text] PATENTEES & MAKERS OF MAGNETIC SPEEDOMETERS FOR MOTOR CARS AND MOTOR CYCLES. A.T. ELECTRIC SCREEN WIPERS AND PETROL LEVEL GAUGES. MOTOR CLOCKS, TACHOMETERS, MILEAGE RECORDERS. REVOLUTION COUNTERS AND INDICATORS FOR MOTOR CARS, MOTOR BOATS, ENGINES, ETC. ALL CLASSES OF SCIENTIFIC INSTRUMENTS. REPAIRS A SPECIALITY. [Main Document Body] 20, Avonmore Road, West Kensington, London, W.14. 18th August, 1927 Messrs. Rolls-Royce Ltd., Nightingale Road, D e r b y. Dear Sirs, We are in receipt of your favour of the 15th instant and have carefully investigated the matter mentioned in your letter and we feel from our wide experience we are justified in stating that providing the instruments which we supply to you are tested at the same temperature at which they were originally calibrated, they will not show any appreciable change for a period of at least five to seven years. We substantiate this by the fact that many instruments with which we originally supplied you, something like five to six years ago have been received back by us for adjustment to the mileage recorder etc. and we have taken special care to test the speed indication on these particular in:struments and we have found that in nearly every instance the instruments had neither gained or lost when tested in normal temperatures. We are also of the opinion that the new modifications which we are fitting into your in:struments will even tend to stabilize the perman:ency of the magnets. We have taken this matter up with the actual manufacturers of the magnets and they confirm our statement most emphatically | ||