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 The A.T. Speedometer Co. regarding temperature variation issues with their large dial speedometer fitted to a Bentley chassis.
| Identifier | ExFiles\Box 59\2\ Scan223 | |
| Date | 10th August 1933 | |
| c. to E.{Mr Elliott - Chief Engineer} c. to C. c. to By.{R.W. Bailey - Chief Engineer} γ 6051 Expl. Dept. Hs{Lord Ernest Hives - Chair}/Wst.S/HJ. 10th. August 1933. The A.T. Speedometer Co. Ltd., Chronos Works, North Circular Road, LONDON. N.W.2. Dear Sirs, Re. A.T. Speedometers for Bentley Chassis. We have been carrying out further tests in connection with the fitting of the large dial A.T. speedometer to the Bentley chassis. A number of points have arisen which we propose to deal with as hereunder :- (1) Variation of reading with temperature. On the Continent with the prevailing Torrid heat we inevitably attain high dashboard temperatures. We are endeavouring to obtain actual measurements in France during this hot summer on a Bentley chassis now running tests in that country and we confidently expect to register temperatures of the order of 45 to 55°C. Contrasting this with the other extreme of temperature in the winter it means that we shall possibly be faced with a variation of 5% in the readings. We consider this on a high priced instrument such as the A.T. to be excessive. A large dial Smith "Nemag" instrument was also tested for temperature variation and we only obtained a variation of 3.0% over the same temperature range as the A.T. which gave 4.0%. In order to satisfactorily compete with this much cheaper "Nemag" instrument, with which we are considerably impressed, we feel we must insist on a smaller temperature variation. We attach our test figures for your examination. Cont'd........ | ||