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 detailing the results of testing new thermostat units and their bellows measurements after 450 miles of running.
| Identifier | ExFiles\Box 156\2\ scan0036 | |
| Date | 11th March 1938 | |
| 1328. March 11th.1938 Rm {William Robotham - Chief Engineer} /Std.7/AP. The British Thermostat Co.Ltd., Teddington Works, Windmill Road, Sunbury-on-Thames, MIDDLESEX. For the attention of Mr.Martin-Hurst. Dear Sirs, We have now completed approximately 450 miles running on one of the new thermostat units EB.3509 which you sent us recently, and which you ensured were correctly set and manufactured etc. As received, the thermostat bellows was labelled 1.437" on your own label which presumably referred to the free length of the bellows before sealing. The compressed length of the bellows as received was 1.280". After 450 miles running, the charge was released and the mean bellows length was approximately 1.530". This indicates no loss of free length due to water pressure but rather the reverse, and satisfies us, taken in conjunction with your own pressure tests that the free lengths of these units are unaffected by external pressure. We also measured the valve lift with the charge released after 450 miles running. This was 0.137" and not .300" as it should be. Accordingly we measured on the second new unit (which was identical with the first one the amount of initial extension of the bellows unit when fitted up with valve in its casing. This was found to be 0.125". Hence starting from the fully compressed state before bellows is fitted in casing, the total movement to the free position would be 1.530 - 1.280 = .250. Of this 0.125" is lost in fitting valve and pulling bellows up into position in the casing. Hence from cold position in casing to free length or punctured position, there can only be .250 - .125 = .125 valve opening. This approximately checks continued | ||