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).
Failure of a bellows unit in an M.Series thermostat system.
| Identifier | ExFiles\Box 156\2\ scan0027 | |
| Date | 17th February 1938 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Std. c. HS.{Lord Ernest Hives - Chair} c. Ds. c. RHC.{R. H. Coverley - Production Engineer} 1328 B.II. THERMOSTAT SYSTEM - M.SERIES. We have had a failure of a bellows unit to EB.3509 on B.23.AE. car after 2200 miles running - this is the scheme which is standardised for M.series Bentley. The failure consisted of a crack at the outside edge of the lowest bellows convolution, allowing the charge to escape. The trouble was detected by the water temperature running at approx 90°C. instead of its customary 75 - 80°C. We have been in communication with the makers on the subject of- (a) Bellows failure. (b) The fact that after failure bellows unit did not run in full open position. Attached is a copy of their reply together with sketch mentioned therein. This system ran 15,000 miles satisfactorily on 3.B.1V. car in France and a similar unit is now running satisfactorily on 3.B.1V. car here. Further, the system was used on the first 15 Bentley cars built, for same period without any trouble of this nature being experienced. We are somewhat sceptical about the British Thermostats Co's explanation of the failure but feel that it would be a wise precautionary measure to use a baffle plate of the type they suggest (held between the thermostat casing and cylinder head flange). Will you please detail the necessary piece and instruct accordingly. The chattering between the bellows top plate and the by-pass seating mentioned in their letter could only have occurred after the unit had failed, since under normal running conditions the bellows top plate never reached the bypass seating. With regard to the failure of the bellows unit to move to the full open position after failure, we have previously tested punctured bellows and it did this quite satisfactorily. We have unsealed the bellows of a comparatively new unit which continued | ||