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).
Technical memorandum comparing the standard Phantom II crankshaft with a stiffer version (E.79351) with large pins.
| Identifier | ExFiles\Box 14\2\ Scan074 | |
| Date | 14th November 1929 | |
| X7010 To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Tsn. c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} c. Rs.{Sir Henry Royce's Secretary} c. E.{Mr Elliott - Chief Engineer} By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Tsn/H.14.11.29. Re : PHANTOM II CRANKSHAFT WITH LARGE PINS E.79351. The torsional period of a standard Phantom II car is 3600 R.P.M. and this stiffer Shaft E.79351 raises it to 3800 R.P.M. or by 5½%. We find the inertia of this shaft is appreciably greater than that of the standard shaft, due to the increase in weight of the pins and webs. The increased stiffness alone should raise the period by 8%, but if we take into account the increase in inertia (which we have measured) the period should only be raised 5%, which is an agreement with practice. The big ends for the large pins do not weight more. Std. Phantom II. Large Pins. Small end. .793 .812 Big end. 2.586 2.450 Total weight: 3.379 lbs. 3.262 lbs. With regard to high speed vibrations generally, a slight improvement is noticeable below the top period. This is always a difficult matter to assess, due to variations in engine feet and body mountings, etc. on Experimental Dept. cars. We shall have the shaft in some more cars shortly. Hs{Lord Ernest Hives - Chair}/Tsn. | ||