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).
Experiments comparing crankshaft vibrations between the Phantom and 20 HP engines.
| Identifier | ExFiles\Box 25\3\ Scan139 | |
| Date | 20th September 1926 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. 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} c. to OY. X634 Hs{Lord Ernest Hives - Chair}/ACL1/LG20.9.26. PHANTOM AND 20 HP. CRANKSHAFT VIBRATIONS. X8010 Y5010 We have carried out further experiments in connection with crankshaft vibrations and have made tests on the Phantom engine to determine if the crankshaft possessed similar characteristics as the 20 HP. By running the engine without slipper wheels we experienced a severe vibration at a speed of 3150 r.p.m. similar to the one at approximately the same speed on the 20 HP. Although this vibration seemed of considerable magnitude judging by the feel and sound of the engine, we do not think it was quite so intense as the 20 HP. under the same conditions and estimated in the same manner. From the nature of it we should imagine this to be the condition of 'resonance' or the case of three oscillations per revolution which would coincide with the three inertia torque impulses per revolution. We have not yet completed our instrument for rendering graphical records of the vibrations similar to that used on the 20 HP., therefore at present have no accurate comparison except such as estimated above. Exploring the speed range we were able to detect slight vibrations at speeds of approx. 1585 and 1105 r.p.m. at full load and these seem to correspond to the half and third of the critical speed as observed in our previous experiments. contd :- | ||