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 characteristics and issues with thermostat-controlled radiator shutters.
| Identifier | WestWitteringFiles\U\August1930-November1930\ Scan060 | |
| Date | 12th September 1930 | |
| To R.{Sir Henry Royce} From Mm/ C. S. S. HS.{Lord Ernest Hives - Chair} C. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} V.{VIENNA} COR. C. W P. To E.{Mr Elliott - Chief Engineer} AV. DR. ORIGINAL Mm/RM.{William Robotham - Chief Engineer}1/HM.{Capt. W. Hallam - Head Repairs}12.9.30. X3499. THERMOSTAT CONTROLLED SHUTTERS. We have received the modification to reduce the friction in the shutters and expect to have a radiator fitted with these completed in a few days. In the mean-time we have taken the characteristics of the Calorstat with and without the spring fitted (curve attached). The main complaint about the existing arrangement without a return spring is that when coasting down a long hill, or after the car has been left standing, the shutters do not close until below 50°C. which is a temperature at which the carburation is unsatisfactory. Furthermore, they open fully at 65°C. which, with the heat we are able to get to the hot spot is too low a temperature for best acceleration especially with poor fuel. (See GWI. 10,000 miles report). If we fill the thermostat with a less volatile liquid, we can increase the temperature at which the shutters open but in doing so we unavoidably increase the slope of the curve on the 'closing' side, in other words the lag in closing will go up more rapidly than it does at present. By a return spring we balance out the power of the thermostat more evenly so that if necessary it can produce almost the same power to close the shutters as it can to open them, instead of the ratio of push to pull being 3-1 as it is at present. | ||