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 detailing the specifications for 20/25 HP Front Flexible Road Springs.
| Identifier | ExFiles\Box 52\2\ Scan285 | |
| Date | 29th May 1931 | |
| THOS. FIRTH & JOHN BROWN, LIMITED. Please note our Telephone Numbers now are :- ATLAS & NORFOLK WORKS - 20081 (11 Lines). TINSLEY WORKS - 41193 (4 Lines). N.95. 27th April, 1931. SHEFFIELD London Office: 8 THE SANCTUARY, WESTMINSTER, S.W.1. Telegraphic Address: "MESMERISM, PARL, LONDON" Telephone Number: 8310 VICTORIA YOUR REFERENCE Hs {Lord Ernest Hives - Chair} /Rm. {William Robotham - Chief Engineer} 8/KT. OUR REFERENCE HWP/AR/838. DEPARTMENT SPRING DEPT. PHONE EXTN T.33. May 29th. 1931. Messrs. Rolls-Royce, Ltd., Nightingale Road, DERBY. 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 Nos. | Thickness Inches. Finished | Lengths Inches. | Ecc. Dist. Ins. | Trial Radii Ins. To Template | Remarks. | |---|---|---|---|---|---| | 1 | .30 | 38+2eyes. | 1.0 | 180 | Span -38 Inches. | | 2. | .16 | 36.0 | .95 | 20 | Width of plate = 1.3/4 Inches. | | 3.X. | .16 | 31.7/8 | .84 | 20 | Load. =700 lbs. | | 4. | .16 | 27.3/4 | .74 | 20 | Free Camber =4.5" positive. | | 5. | .16 | 23.3/4 | .64 | 20 | Loaded " =.5" " | | 6. | .16 | 19.7/8 | .54 | 20 | Deflection due to load = 4 Inches. | | 7.X. | .16 | 16.0 | .44 | 20 | Clip plates marked X. | | 8. | .16 | 12.1/4 | .35 | 20 | | | 9. | .16 | 8.1/2 | .25 | 20 | | | 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. Yours faithfully, THOS. FIRTH & JOHN BROWN, LIMITED. Director. P.S. Above mainplate thickness is ground flat. Other plate thicknesses are concave buffed. | ||