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 a supplier regarding the failure of a thermostat unit used on production Bentley cars.
| Identifier | ExFiles\Box 137\2\ scan0030 | |
| Date | 11th February 1938 | |
| Rm{William Robotham - Chief Engineer}/Std.4/MH.{M. Huckerby} 11th. February 1938. The British Thermostat Co. Ltd., Teddington Works, Windmill Road, Sunbury-on-Thames, MIDDSX. For the attention of Mr. Martin-Hurst. Dear Sirs, We have received your letter of 10th. inst., for which we thank you and also the three heater switches mentioned therein. Our official order for same will follow. We are to-day returning to you one of the thermostat units to EB.3509 which you have supplied to us, this has failed after 2200 miles running, having cracked at the outer edge of the lowest convolution. We are extremely concerned about this failure since as you know, this unit has been standardised on production Bentley cars. We would like you to examine this unit and let us have your remarks on same by return if possible. Also let us know whether there are any steps which you can take to prevent recurrence of this trouble. In connection with this failure, a further defect has arisen - the failure was noticed since the water temperature ran at 85-90°C instead of its customary 75°-85°C. Our previous tests with older units of similar type have shown that with a punctured bellows the water temperature has run low instead of high. The reason for this difference appears to be that the free position of this bellows, i.e. punctured, with atmospheric pressure inside and outside it, is such that the valve head is only .060 approximately off its seat. The question of free length | ||