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 stiffness, weight, and features for a new S.S. crankshaft with large pins against standard shafts.
Identifier | ExFiles\Box 31\1\ Scan011 | |
Date | 29th August 1929 | |
[Handwritten top center] X1418. [Top right, typed] Hs{Lord Ernest Hives - Chair}/Tsn.1/MJ.29.8.29. [Top right, handwritten] X7010 X8010 X1418. S.S. CRANKSHAFT WITH LARGE PINS ------------------------------- We have twisted this shaft in its piads [handwritten above: case], and find it to be 17% stiffer torsionally than the standard S. S. shaft and 40% stiffer than the original standard Phantom shaft. The figures are :- Original Std. Phantom E.{Mr Elliott - Chief Engineer} 75216 - 45,000 lbs. ft/rad. Std. S.S. (unchamfered) - 52,700 " " " Large Pin S.S. E.{Mr Elliott - Chief Engineer} 79531 - 62,800 " " " The latter shaft incorporates the following features:- Pin dia. increased from 2.125 to 2.375". Pin bore reduced from 1.125 to 1.00". Journal bore reduced from 1.500 to 1.00". Web width 4.000" as before. The webs are unchamfered, as this feature has now been adopted on production. The reasons being that it gives a significant increase in stiffness, and very considerably simplifies the production. The weights of the above shafts are :- Original Std. Phantom 75 lbs. 12ozs. Std. S.S. (unchamfered) 79lbs. 8ozs. Large pin S.S. 90 lbs. 14ozs. We cannot get big-end weights yet for the new shaft. The stiffness of a single crank comes out at 6.2 x 10^6 lbs.ins/radian, as against a calculated figure using Carter's formula of 7.03 x 10^6 lbs. ins/radian. The formula is thus 13% too high. [Bottom right] Hs{Lord Ernest Hives - Chair}/Tsn. | ||