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 Thos Firth & Sons detailing an alternative design for 20/25 HP front flexible road springs.
| Identifier | ExFiles\Box 106\1\ scan0268 | |
| Date | 29th May 1931 | |
| COPY. THOS FIRTH & SONS LIMITED NORFOLK WORKS SHEFFIELD. Messrs. Rolls-Royce Ltd., Nightingale Road, D E R B Y ? May 29th, 1931. 20/25 HP. Front Flexible Road Springs. For the attention of Mr. Harvey Bailey. Dear Sirs, We give below particulars of the further alternative design of these springs to your ideas contained in your letter of 21st inst., signed by Mr. Robotham. These springs are referred to in Mr. Stanfield's letter of even date. Plate Thickness Lengths Ecc. Trial Nos. Inches Inches Dist. Radii Remarks. Finished. Ins. Ins. To Template 1. .30 38+2eyes 1.0 180 Span 38 ins. 2. .16 36.0 .95 20 Width plate 1 3/4 ins 3.X. .16 31.7/8 .84 20 Load 700 lbs 4. .16 27.3/4 .74 20 Free camber 4.5 pos. 5. .16 23.3/4 .64 20 Loaded " .5 pos. 6. .16 19.7/8 .54 20 Deflection due 7.X. .16 16.0 .44 20 to load 4 ins. 8. .16 12.1/4 .35 20 9. .16 8.1/2 .25 20 Clip plates marked X. Totals 1.58 Please note that :- (1) Range of stress in Mainplate to the loaded position. = 43 Tons per sq.inch. (2) Range of stress in Mainplate to the maximum bump position = 69 Tons per sq.inch. P.S. Above mainplate thickness is ground flat. Other plate thicknesses are concave buffed. Yours faithfully, THOS. FIRTH & JOHN BROWN LTD. | ||