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).
Tests for a 20 HP crankshaft, detailing findings and proposed modifications to increase stiffness.
| Identifier | ExFiles\Box 25\3\ Scan292 | |
| Date | 12th December 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} X634 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG6.12.27. CRANKSHAFT TESTS. (underlined) X634 (written over crossed-out X5010) We have carried out tests on a 20 HP. crankshaft in various stages from the rough forging to the finished article. Throughout the test the shaft was only supported at the two end bearings, hence when approaching the finished condition its stiffness suffers somewhat from this fact. On the whole the results bear a very reasonable proportionality to the R.A.E. formula. The conclusions that we have come to as a result of these tests are :- (a) Possible modifications to present 20 HP. shaft as shown on Lec.2480. (underlined) (1) Reduce bore of hole through journal to .5" - Anticipated increase in stiffness 8%. (2) Increase breadth of web to 3.5" to compare with the Stutz. Anticipated increase in stiffness 15-20%. For future modifications the factor that strikes one at once is the relative weakness of the pins. (b) Future modifications necessitating re-designed crankcase. (underlined) (1) Increase in dia. of pins to 2.00" and reduction in width of webs from .8" to .6". Additional bearing length available in consequence to be shared between big ends and main bearings. Estimated increase in stiffness 30-35%. From our test we confirm that the new 20 HP. shaft to Lec.2480 would appear to be about 30% stiffer than std. We have not measured an actual shaft yet. Superficially, therefore it would appear that the stiffness of the 20 HP. shaft can contd :- | ||