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).
Hypothesis on flywheel vibration frequency and crankshaft smoothness, with proposed experiments.
| Identifier | ExFiles\Box 14\2\ Scan066 | |
| Date | 1st November 1939 | |
| -15- Hs{Lord Ernest Hives - Chair}/Tan5/DB.{Donald Bastow - Suspensions}11.39.contd. a lot of facts in to be sure of our theory. From the above hypothesis we would expect to gain an improvement from either raising or lowering the frequency of vibration of the flywheel, since in the former case the vibration speed might be outside our range of R.P.M. while in the latter case it would be at a low R.P.M. where the crankshaft rotates fairly steadily. In any case it is a strong argument for improving the smoothness of operation of the crankshaft. We propose to do some experiments on a rig to try amongst other things the effect of a steady bearing on the rear projecting spigot, and also of weakening off the supporting plate (bolted to the crankshaft) to about .050" thick. A flywheel has no tendency to vibrate on its own, even if out of dynamic balance, in which respect it differs from a long shaft. If mounted out of truth on a flange, but otherwise in static balance then the centrifugal forces due to the dynamic out-of-balance merely tend to reduce the out of truth. This may be demonstrated mathematically, and is a consequence of its polar inertia being greater than the inertia about a diameter, which is why it differs for instance from a long cylinder rotating about an axis inclined to its own axis. Here the centrifugal forces would tend to increase the out-of-truth. | ||