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. regarding the use of 'Alumbro' for thermostat bellows and measurement discrepancies.
| Identifier | ExFiles\Box 156\2\ scan0051 | |
| Date | 30th March 1938 | |
| 1328 March 30th.1938 RM{William Robotham - Chief Engineer}/Std.11/AP. The British Thermostat Co.Ltd., Teddington Works, Windmill Road, Sunbury-on-Thames, MIDDLESEX. For the attention of Mr.Martin-Hurst. Dear Sirs, Referring to our telephone conversation of today, you will make the first 30-40 production thermostats to EB.3509 with bellows in 'Alumbro' instead of 80/20 brass as previously used, without any alteration to the quotation figure. We will test the first 'Alumbro' bellows which are you sending us, to determine whether any reduction of free length occurs after running - in any case since you state that this material is superior to 80/20 brass, it will be advisable to use it. Will you please be good enough to let us know what effect the change of material has on the temperature control range of the thermostat, and also the precise specification of 'Alumbro' material. We cannot understand the discrepancy between your measurements and our own since according to your figures even with the .038" reduction in free length which you state, the opening of the valve with the bellows punctured would be 1.657 (free length after running measured by yourselves) - 1.259 (cold length on internal stop) - .156 (initial pull up on bellows in casing - measured by us) = .252. Actually the opening of the valve under these conditions was definitely only .167 i.e. .085 less than your figures indicate. However, we are going to recheck on the second thermostat unit which we have. We are returning to you two of the three car heater switches which you sent us recently - these have been used singly continued | ||