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 special springs with increased deflection for a 20 HP Chassis, detailing changes to mainplate thickness and resulting stress.
| Identifier | ExFiles\Box 52\2\ Scan264 | |
| Date | 18th December 1930 | |
| Y4429. ALL COMMUNICATIONS TO BE ADDRESSED TO THE COMPANY. Telegraphic Address: 'FIRTH SHEFFIELD' Telephones: NORFOLK WORKS SHEFFIELD 23031 TINSLEY WORKS ATTERCLIFFE 41193 Codes PRIVATE, A.B.C. 6TH EDITION, BENTLEYS 1912 & 1929 LIEBERS, LOMBARD, MARCONI, WESTERN UNION, 5 LETTERS 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 OUR REFERENCE: HWP/AR/748. DEPARTMENT: SPRING DEPT. PHONE EXTN: T:33. RECEIVED 19 DEC 1930 December 18th. 1930. Messrs. Rolls-Royce, Ltd., Nightingale Road, DERBY. Special Springs with increased deflection Your Order 10525 of 13/12/30. Dear Sirs, The 4 Front and 4 Rear Springs as called for on above order for your 20 HP. Chassis 18.G.4, have been designed and the work placed in hand in the shop. In the front spring we are making the mainplate the minimum of .34" thick as against .25" thick in the standard spring, thus raising the range of stress in the mainplate from 18 to 29.2 Tons per square inch, caused by your demand for a little over 50% increase in deflection. In the rear spring we are making the mainplate thickness .25" as against .281" in your standard spring, thus raising the range of stress from 23.8 to 26.5 Tons per square inch, caused by your demand for 25% increase in deflection. In both front and rear springs the plate lengths and clip centres are as per standard. You will observe that the increase of range of stress in the front spring is very considerable, but these new design of springs are the best we can recommend subject to test by you. Yours faithfully, THOS. FIRTH & SONS, LIMITED. B.C. Muckleshwaite for Director. By HJS/AW | ||