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 regarding the design and manufacturing of five-leaf light springs following a test failure.
| Identifier | ExFiles\Box 52\2\ Scan216 | |
| Date | 19th March 1930 | |
| 14429 ALL COMMUNICATIONS TO BE ADDRESSED TO THE COMPANY. Telegraphic Address: 'FIRTH SHEFFIELD' Telephones: NORFOLK WORKS SHEFFIELD 23031 TINSLEY WORKS ATTERCLIFFE 41193 Codes: ABC WESTERN UNION AI BENTLEYS LIEBERS ETC THOS. FIRTH & SONS, LIMITED NORFOLK WORKS SHEFFIELD London Office: 8 THE SANCTUARY, WESTMINSTER, S.W.1. Telegraphic Address: 'MESMERIC PARL LONDON.' Telephone Number: 8510 VICTORIA. YOUR REFERENCE: Hs {Lord Ernest Hives - Chair} /Rm. {William Robotham - Chief Engineer} 2/MJ. OUR REFERENCE: HWP/AR/528/1. DEPARTMENT: SPRING DEPT. PHONE EXTN.: T.30. March 19th. 1930. Messrs. Rolls-Royce, Ltd., Nightingale Road, D E R B Y. For the attention of Mr. Robotham. Sports type Five Leaf Light Springs for 23.E.X. Dear Sirs, We thank you for your letter of March 14th. together with the tip which was broken off the 4th leaf of one front spring during test. You will recollect that these springs were not put forward as a recommended design, but were offered in order to comply with the requirements of a spring to come within a specified maximum light weight. The chief difficulty with such a design is that with the small number of leaves necessary, the overlaps of the plate ends are necessarily very long. The tapering of the plate tips should theoretically be carried right up to the next plate end. When the plates were being tapered we gave them the maximum possible on our Snow Grinder, but we will now endeavour to increase the taper to your requirements either through making a temporary adjustment on the machine or by machining or hand grinding as we find most suitable. This explains why the plate tips as supplied, were not as flexible as desirable to give the best results. In addition to this the holes drilled for fixing the clips came close up to the position of full stress on the plates and had a considerable weakening effect. We presume the modified drawing you are sending to us will incorporate the longer tapered end, which, considered as an experimental job, we should agree with, but not for bulk quantities. We recommend also that the clip centres which no doubt will be shown on your drawing should be fixed on the taper of the plate, closer to the plate ends, preferably with smaller rivet holes than our standard 1/4" dia. P.S. We find today that with a temporary adjustment to our Snow Grinder, we can for a few plates obtain a maximum taper of 4.1/2". Yours faithfully, THOS. FIRTH & SONS, LIMITED. [Signature] Director. | ||