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).
Comparison of specifications, plate dimensions, and stresses for three different spring designs.
| Identifier | ExFiles\Box 52\2\ Scan274 | |
| Date | 8th April 1931 guessed | |
| Existing Springs (A) Load: 2150 lbs (plus) Deflection .5 1/2" Free Camber: 3.75" + Loaded Camber: 1.5" Neg. Suggested Spring (B) Revised Specification:- Load. 2720 lbs. Deflection .5 1/2". Free or unloaded Camber 3.75". + Loaded Camber 1.5" Neg. Alternative Spring (C) Revised Specification:- Load. 2720 lbs. Deflection .5 1/2". Free or unloaded Camber 3.75". + Loaded Camber 1.5" Neg. Table 1: Plate Details Existing Spring (A) - 11 PLATES Plate Nos. | Finished Thick/ss {S. Smith} Inches | Lgths of Plates Inches 1. | .29 | 53+Eyes. 2. | .29 | 53.1/2 3. | .29 | 48.1/2 4.X. | .29 | 43.1/2 5. | .28 | 38.1/2 6. | .28 | 33.0 7.X. | .28 | 28.3/4 8. | .28 | 24.0 9. | .28 | 19.1/4 10. | .28 | 14.1/2 11. | .28 | 9.3/4 Totals. 3.12 Suggested Spring (B) - 12 PLATES Plate Nos. | Finished Thick/ss {S. Smith} Inches | Lgths of Plates Inches 1. | .30 | 53+Eyes. 2. | .30 | 53.1/2 3. | .30 | 49.0 4.X. | .30 | 44.1/2 5. | .30 | 40.0 6. | .30 | 35.1/4 7. | .30 | 31.0 8.X. | .30 | 26.5/8 9. | .30 | 22.1/4 10. | .30 | 17.7/8 11. | .29 | 13.1/2 12. | .29 | 9.1/8 Totals. 3.58 Alternative Spring (C) - 14 PLATES Plate Nos. | Finished Thick/ss {S. Smith} Inches | Lgths of Plates Inches 1. | .29 | Note:- 2. | .29 | Lgths of 3. | .29 | Plates, 4. | .29 | Clip 5. | .28 | Plates & 6. | .28 | Clip 7. | .28 | Cnts to 8. | .28 | be deter 9. | .28 | mined by 10. | .28 | you if 11. | .28 | you 12. | .28 | prefer 13. | .28 | this 14. | .28 | Spring Totals 3.97 NOTE:- Where clip plates are marked X for clip centres see your blue print F.10612. Table of stresses for Springs A, B & C. Existing Spring (A) 11 Plates - Tons per sq. in. Range of stress in Mainplate to loaded position. | 38.3 Ditto to Max Bump Position. | 41.6 Stress in static Position (Bending) | 34.5 Suggested Spring (B) 12 Plates - Tons per sq. in. Range of stress in Mainplate to loaded position. | 29.1 Ditto to Max Bump Position. | 43.0 Stress in static Position (Bending) | 36.1 Alternative Spring (C) 14 Plates - Tons per sq. in. Range of stress in Mainplate to loaded position. | 28.8 Ditto to Max Bump Position. | 41.6 Stress in static Position (Bending) | 34.3 | ||