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 regarding pressure testing of a Bentley thermostat unit and performance of heater motor rheostats.
| Identifier | ExFiles\Box 156\2\ scan0104 | |
| Date | 25th April 1938 | |
| 1328 Telephone: SUNBURY-ON-THAMES 456 (6 LINES) THE BRITISH THERMOSTAT CO., LTD. Makers of Scientific Instruments. Telegrams & Cables: THERMOSTAT, SUNBURY-ON-THAMES. CODE: BENTLEY'S DIRECTORS: COL. N. HUDSON. J.{Mr Johnson W.M.} E.{Mr Elliott - Chief Engineer} SHERLOCK } MANAGING. W.F.P. MARTIN-HURST } L.S. SWINNERTON DYER. F.G. POPLETT. TEDDINGTON WORKS. Windmill Road, Sunbury-on-Thames, Middlesex. WMH/GN: April 25th, 1938. Your Ref: Messrs. Rolls-Royce Ltd. DERBY. [Illegible handwriting] Dear Sirs, For the attention of Mr.C.Steadman. Confirming our telephone conversation this morning, we are pressure testing the Bentley Thermostat unit to-day and we will fit progressively smaller bellows until the sudden closing of the valve due to lack of pressure balance is eliminated. When we hear from you regarding the maximum size to which the seating can be increased, we will let you know the size of bellows which gives the best results. With regard to Heater Motor Rheostats, we have been carrying out some tests, and find that the maximum temperature rise when a standard rheostat is used in series with a motor consuming 22 watts is only 161°F.{Mr Friese} The corresponding figure for a motor using 17½ watts is 107°F.{Mr Friese} It seems improbable, therefore, that the burn-outs can have occurred while the motor was running normally, and we can only assume that the motor must have stuck in each case, thus causing current increase. The writer does not very clearly understand whether it is your wish that we should do anything further with these rheostats, or whether you would obtain them from Joseph Lucas. If you would like us to send you further samples for trial we will willingly do so. Yours truly, THE BRITISH THERMOSTAT CO., LTD. [Signature] W.Martin-Hurst. | ||