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 outlining the technical requirements for a thermostat bellows to operate bonnet shutters.
| Identifier | ExFiles\Box 156\1\ scan0115 | |
| Date | 23th October 1935 | |
| X1328 Exptl. Dept. Hs {Lord Ernest Hives - Chair} /Std.20/KW. 23rd October,1935. The British Thermostat Co.Ltd., Windmill Road, Sunbury, Middlesex. For the attention of Mr. Martin-Hurst. Dear Sirs, We shall shortly be requiring a thermostat bellows to operate a set of bonnet shutters which we wish to test. The requirements for the thermostat (which should be of the shutter operating type, i.e., have the operating fluid in an annular space surrounding the bellows) are as follows. Travel of operating lever attached to bellows - 0.5". Load against which bellows has to work - 7 lbs. Maximum temperature at which bellows reaches full travel (0.5") against 7 lbs. resistance - 48°C. Minimum temperature at which bellows fully close against resistance of 7 lbs. - 28°C. NOTE: The resistance in question is a frictional one and the temperatures are approximate. We have made some preliminary calculations, from which it appears that the smallest suitable thermostat is one having a bellows mean area of 1.6", with a rating (spring) of 21.2 lbs/in., using ether (B.P. 35°C.) for a filling, and making the closed length of bellows equal to the free length of same. | ||