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).
Table comparing various specifications for different normal spring loads.
| Identifier | ExFiles\Box 154a\4\ scan0133 | |
| Date | 12th March 1940 | |
| Ev {Ivan Evernden - coachwork} /DB. {Donald Bastow - Suspensions} 10/JH.12.3.40. Normal Spring load. 700 lb. 750 lbs. 800 lb. Wire diameter. 0.610" 0.619" 0.635 Mean diameter of coils. 5.285" 5.294" 5.310" Number of effective coils. 6½ 6¼ 6¼ Normal load. 1230 lbs. 1320 lbs. 1408 lbs. Normal deflection. 5.925" 5.785" 5.665" Normal stress, incorrected. 73,100 lbs/in.sq. 75,100 lbs./in.sq. 74,600 lbs/in.sq. Maximum load. 1547 lbs. 1669 lbs. 1788 lbs. Maximum deflection. 7.455" 7.315" 7.195" Maximum stress, uncorrected. 92,00 lbs/in.sq. 94,800 lbs/in.sq. 94,700 lbs/in.sq. Maximum stress, corrected. 107,000 lbs/in.sq. 110,500 lbs/sq.in. 110,700 lbs/in.sq. Rate. 207.5 lbs/in. 228 lbs/in. 248.5 lb/in. Rate at wheel due to spring alone. 64.4 lbs/in. 70.7 lbs/in. 77.1 lbs/in. Total rate at wheel, including rubber bushes. 87.4 lbs/in. 93.7 lbs/in. 100.1 lb/in. Corresponding static deflection. 8.01" 8" 7.99" Room for packing. 0.42" 0.55" 0.46" | ||