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 British Thermostat Co. Ltd. discussing the testing and performance of their corrected thermostats.
| Identifier | ExFiles\Box 156\1\ scan0072 | |
| Date | 15th April 1935 | |
| +4508 Exptl. Dept. Hs {Lord Ernest Hives - Chair} /Std.19/KW. 15th April, 1935. Your Ref: WMH/GN.10.4.35. The British Thermostat Co.Ltd., Windmill Road, Sunbury, Middlesex. For the attention of Mr. W. Martin-Hurst. Dear Sirs, We have received your letter of the 10th inst., for which we thank you, together with the six corrected thermostats. We have tested these and find that they correspond approximately to the figures you quote. With regard to the question of limits and manufacturing problems with these thermostats, we realise your difficulties and should like to draw your attention to the following points. The thermostat as assembled by us has an external stop limiting its movement to .250. This movement has not been exceeded by any of other thermostats which we have tested. The range of operation which we selected for these thermostats (7° i.e., 75°C. - 82°C.) was decided on from experience with thermostats supplied to us by yourselves, to drawing EB.667 attached. Four such thermostats when tested by us commenced to open at 76.5, 78, 79 & 80°C. respectively and were fully open (.300 lift) at 83.5, 84, 84 & 84°C. respectively. This corresponds to a maximum variation in opening temperature of 3.5°C. These thermostats in operation on the road were satisfactory, giving our required minimum variation of temperature, hence we naturally decided to use the same temperature range, and specify an opening temperature of 75°C. | ||