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 from a supplier discussing the design and testing of alternative flexible road springs for a 20 HP car.
| Identifier | ExFiles\Box 52\2\ Scan281 | |
| Date | 27th May 1931 | |
| THOS. FIRTH & JOHN BROWN LIMITED. ALL COMMUNICATIONS TO BE ADDRESSED TO THE COMPANY. ATLAS AND NORFOLK WORKS. Codes: PRIVATE A.B.C. 6TH EDITION. BENTLEYS 1912 & 1929. LIEBERS. LOMBARD. MARCONI. WESTERN UNION, 5 LETTERS FORMERLY THOS FIRTH & SONS, LIMITED NORFOLK WORKS SHEFFIELD Telegraphic Address: 'FIRTH SHEFFIELD' Telephones: NORFOLK WORKS SHEFFIELD 23031 TINSLEY WORKS ATTERCLIFFE 41193 London Office: 8 THE SANCTUARY, WESTMINSTER, S.W.1. Telegraphic Address: 'MESMERIC PAR, LONDON' Telephone Number: 8310 VICTORIA. OUR REFERENCE DEPARTMENT: SPRING DEPT. REFERENCE: HWP/AR/836/2. PHONE EXTN.: T.33. May 27th. 1931. Messrs. Rolls-Royce, Ltd., Nightingale Road, DERBY. 1 Pair 20 HP. Flexible Road Springs. For the attention of Mr. W.A.Robotham. Dear Sirs, We have carefully studied your letter of 21st inst. In view of the fact that you wish us to design these springs for test to a stress slightly lower than those you have tested, we submit on attached sheet three alternative springs for your consideration. You will observe that in no case are the mainplates .30" thick for the reason that were they so, whilst attempting to maintain the spring deflection at 4" due to load with 38" span, they would be very considerably over stressed to 43 Tons per square inch. You will readily agree that this figure is much too high for front springs. You will also note that we have kept the same span 38", and fixed slightly reduced the deflection below those you have tested, as will give you increased flexibility over your old standard (2" deflection). Moreover, their range of stress is slightly lower than the high deflection springs which you have tested. We believe that these alternatives represent the best compromise under the circumstances, and should you approve of any one of them, and let us know the maximum and minimum dimensions for clip centres, we shall be pleased to prepare the necessary drawing forthwith for you to submit to Sir Henry Royce. Yours faithfully, THOS. FIRTH & JOHN BROWN LIMITED, Director. | ||