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).
Vibrations in a 20 HP disc crankshaft compared to a standard crankshaft.
| Identifier | ExFiles\Box 74\4\ scan0114 | |
| Date | 26th September 1924 | |
| R.R. 496A (20H) (D.A. 652 20-3-24) J.H.D. Handwritten: X4604 EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}2/LG26.9.24. 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 EP.{G. Eric Platford - Chief Quality Engineer} Handwritten: X4221 X4601 20 HP. DISC CRANKSHAFT. We have a 20 HP. engine arranged so that we can change [strikethrough]xxxxxxxxxx[/strikethrough] over from the standard crankshaft to the disc type crankshaft using all other parts the same. Without the friction damper fitted, we still get definite crankshaft periods with the disc crankshaft. We will send a further report giving a comparison of the exact speeds at which they come on, with the standard and disc crankshafts. With the friction damper fitted, we can eliminate the usual torsional vibrations but with the disc crank, we get a very bad period from 2750 to 3000 revs. You will remember that considerable investigation was carried out in connection with this high speed vibration on the 20 HP. and although a number of experiments were made, no definite conclusions were arrived at as to the cause of it. On the standard 20 HP. cars, we now seldom hear of it. During some investigations we ran a standard 20 HP. engine which was particularly free from this fault. The engine was dismantled and overhauled and the bearings re-fitted; the high speed vibration was then pronounced. It is our intention to confirm this test at the next opportunity. Hs.{Lord Ernest Hives - Chair} | ||