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).
Comparing a standard Phantom II crankshaft with a new, stiffer version (E.79351) with large pins, analysing changes in torsional period, inertia, weight, and high-speed vibrations.
| Identifier | WestWitteringFiles\T\2July1929-December1929\ Scan156 | |
| Date | 14th November 1929 | |
| To R.{Sir Henry Royce} c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} c. Rg.{Mr Rowledge} c. E.{Mr Elliott - Chief Engineer} c. BY.{R.W. Bailey - Chief Engineer} ORIGINAL file K7010 Hs{Lord Ernest Hives - Chair}/Ten/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 in agreement with practice. The big ends for the large pins do not weigh 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} | ||