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).
Copy of a letter from The British Thermostat Co. Ltd to John Marston Ltd regarding a 12-volt plain bearing motor.
| Identifier | ExFiles\Box 135\1\ scan0116 | |
| Date | 28th January 1938 | |
| COPY of letter from :- THE BRITISH THERMOSTAT CO. LIMITED, Windmill Road, Sunbury-on-Thames, Middlesex. WHM/GN 28th January, 1938 Messrs. John Marston Limited, WOLVERHAMPTON. Dear Sirs, For the attention of Mr. Dunn We thank you for your letter of January 27th. We are sending you a 12 volt plain bearing motor with a fixing bracket, as shown on our drawing, for trial purposes. Do you wish us to supply a fan or will you make your own arrangements, we have a few 6" diameter fans and can let you have one if you wish, although if you intend to compare the running noise of this motor with another, it would, of course, be desirable to use the same fan on both motors. The motor runs at approximately 2300 revs. on a 6" diameter fan at a consumption of 12.6 watts, giving an efficiency of 30.08% or 1700 revs. on a 9 1/2" diameter fan, at a consumption of 16.8 watts, giving an efficiency of 32.8% While these efficiencies are low compared with those obtained with larger machines, they appear to be as good as the best fan motors at present on the market and very much better than the majority. We can of course rewind the motor to increase the speed should this be necessary. We regret that it will be a few days before we are able to quote you as our costs are not yet finalised. The matter will, however, have attention as soon as possible. Yours truly, THE BRITISH THERMOSTAT CO. LIMITED. | ||