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).
Torsion tests for the India 3 crankshaft, comparing its stiffness against the standard 20 HP shaft.
| Identifier | WestWitteringFiles\S\March1928-May1928\ Scan056 | |
| Date | 23th March 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Tsn. c.c. to BJ. Wor.{Arthur Wormald - General Works Manager} c.c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c.c. to BY.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Tsn2/LG23.3.28. [STAMP] ORIGINAL INDIA 3 CRANKSHAFT - TORSION TESTS. [Handwritten] X5010 X418 This shaft is E.54640 (Lec.2480) - it is the intermediate stiffer shaft - the later shaft with larger dia. pins will be on test shortly. It has the oval webs and 2.125 journals. When twisted in all seven bearings its stiffness is 26,100 lbs.ft./radian, or 37.5% stiffer than the standard 20 HP. shaft. When twisted in either three or two bearings, the stiffness drops to 21,050 lbs.ft/radian, - A fall of 19%. This is interesting, as it tends to bear out our experience that when the weakest part of the shaft is the crankpin, the presence of the bearings makes a considerable difference. We should expect from this that when running on a torsional period, the main bearings would receive considerable hammering. Also that the degree of fit or amount of wear in the bearings will produce noticeable alterations in the severity of the periods. It can be seen by twisting wire crankshafts that the cranks tend to unwind themselves by the process of twisting the crankpins. The crankpin term in Major Carter's formula is 3/4 a (d1^4 - J1^4) / (d2^4 - J2^4) This represents the equivalent length of one pin. The following table gives the percentage that the crankpin term contributes to the total equivalent length of one crank, together with the | ||