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).
Crankshaft design, bearing wear, and vibration issues in 20 HP cars.
| Identifier | ExFiles\Box 74\3\ scan0297 | |
| Date | 26th November 1924 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} 4221 20 HP. 4634 Hs{Lord Ernest Hives - Chair}6/LG26.11.24. We propose bringing to WW. (with 93-NK car), 7-G-11. The unit in this car is fitted with the disc crankshaft. We think it would be interesting for you to compare 4-G-11 car fitted with the stiffer crankshaft of standard design, and 7-G-11 with the disc crankshaft which has the same dimension journals and crankpins. Since our last visit to WW. we have dismantled an experimental unit fitted with a larger dia. crankshaft which has run approx. 9,000 miles on the road and 300 hrs. on the bench test. We found that the journal bearings, especially the intermediates, were in poor condition. We will bring these to WW. This is the third occasion when we have had trouble with bearings on an engine fitted with a stiffer crankshaft. We had thought that these troubles would have been overcome by the disc crankshaft because on there we have considerable increase in the length of the bearings, still retaining the larger journals. The disc crank however is very poor for vibrations. 4-G-11 car which is at present at WW. is, we consider, the best 20 HP. we have tried for absence of crankshaft vibrations at high speeds. We were able to run that car up to 50 m.p.h. on second speed, before it left, without contd :- | ||