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 concerning corrections to calculations on a drawing for thermostat bellows.
| Identifier | ExFiles\Box 156\1\ scan0137 | |
| Date | 5th December 1935 | |
| Telephone: SUNBURY 456 (4 LINES). Codes: BENTLEY'S, WESTERN UNION. Telegrams & Cables: THERMOSTAT, SUNBURY COMMON. Steadman THE BRITISH THERMOSTAT CO., LTD. Makers of Scientific Instruments. DIRECTORS: M.{Mr Moon / Mr Moore} PAYNE. W. A.{Mr Adams} PAYNE. J.{Mr Johnson W.M.} E.{Mr Elliott - Chief Engineer} SHERLOCK. L. S. SWINNERTON-DYER. TEDDINGTON WORKS. Windmill Road, Sunbury, Middlesex. Your Ref: Hs{Lord Ernest Hives - Chair}/Std.2/KW: W.M.H/GN: December 5th, 1935. Messrs. Rolls-Royce Limited, DERBY. Dear Sirs, For the attention of Mr. Steadman. We must apologise for the delay in replying to your letter of November 19th. We are obliged to you for correcting the two errors which we made in the calculations shown on our Drawing No. BGA. 3201 enclosed with our letter of November 12th. These we regret to say were made very hurriedly and were not checked. We agree with your figure as far as the calculations are concerned, although the rate of a 5" bellows is 22½ lbs. for 1/8", not 12 lbs. as you have assumed. We have looked into the possibility of using a smaller thermostat acting direct, and having a travel of ½", and the smallest diameter which would meet the case is a bellows 2.3/8" o/d, 19 convolutions, measuring about 2¾" overall when free. For this thermostat the calculations are shown on the enclosed page. You will notice that it is only just possible to get the required results when using a spring having a rate of 2.32 lbs. per inch travel. Unfortunately the next size of bellows, 2.7/8" o/d, | ||