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).
The testing of a Hobson remote acting thermostat, noting issues with sticking and comparing it to standard calorstats.
| Identifier | ExFiles\Box 156\1\ scan0108 | |
| Date | 7th June 1935 | |
| To E. {Mr Elliott - Chief Engineer} c. to By. {R.W. Bailey - Chief Engineer} X1328 Hs {Lord Ernest Hives - Chair} /Std.7/KW.7.6.35. Report on Hobson Remote Acting Thermostat. We have tested this thermostat in the usual manner by measuring the necessary push or pull to hold the top plate (a) .010" from cold position, (b) .375" from cold position - corresponds to practically full movement. We have also taken a curve of free movement (no external load) against temperature. During the last test some rather peculiar sticking was experienced. On two occasions, temperatures of 92 and 96oC. were registered before any movement was registered and when movement did take place it did so very rapidly, this in spite of the fact that the bellows were expanded mechanically to a small extent to overcome any friction. As we are not aware of the internal construction of this thermostat, we are unable to account for this sticking. The thermostat did not seem to have any internal guide. The results obtained are attached in graphical form. Summary. It appears that the only advantage over our standard calorstats possessed by this thermostat is that of being remote reading, and capable of use where high temperatures are likely to occur, e.g., in exhaust system. The thermostat as it stands at present will not develop the forces which our standard calorstats do, and even if its bellows were equal in size to our standard ones, we do not think it would give as good results. However, given the correct filling, there seems to be no reason why it should not give reasonably good results. Hs {Lord Ernest Hives - Chair} /C.S.Steadman. | ||