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).
Vibration, whirling, and balancing issues with the Peregrine intermediate transmission shaft.
| Identifier | ExFiles\Box 179b\3\ img368 | |
| Date | 27th March 1933 | |
| To R.{Sir Henry Royce} from Ha/Gry.{Shadwell Grylls} c. Ag. Hsr. c. S. Sy. c. Da.{Bernard Day - Chassis Design} Ha/Gry.{Shadwell Grylls}15/KT.27.3.33. XJ427 PEREGRINE TRANSMISSION SHAFT. R4/M10.3.33. Perhaps we have not made it clear that the trouble with the early Peregrine intermediate transmission shafts was not whirling of the main propeller shaft, but a vibration of the cross member supporting the spherical bearing, due to unbalance of the propeller shaft. Rough periods were experienced at about 45 and 65 m.p.h. due we considered to the out of balance force synchronising with the natural frequency of the cross member in a vertical plane. Dynamic balancing has overcome this but has not raised the speed at which the centre of the propeller shaft begins to run out of truth due to incipient whirling. With the present short shaft of 2.25" diameter, this speed is above 5000 r.p.m., higher than which we are not able to run. If we have to correct unbalance of a shaft, caused by the tube being eccentric with the coupling flanges, this shaft will probably whirl at a lower speed than a good one in spite of being dynamically balanced. All we claim for dynamic balancing is that the bearings supporting the propeller shaft are relieved of any centrifugal loading. Ha/Gry.{Shadwell Grylls} | ||