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).
Letter to H.M. Crane discussing the working principle of a torsional vibration damper.
| Identifier | ExFiles\Box 25\3\ Scan214 | |
| Date | 25th November 1926 | |
| COPY. CWB2/GM/251126. 25th November, 1926. H.M. Crane, Esq., 40 East Fifty-fourth Street, New York, N.Y. U.S.A. Dear Crane, I am very interested from the technical point of view in the torsional vibration damper which has been adopted by you on some of your chassis, e.g. the Buick, because it would appear that this device operates upon a slightly different principle to the more conventional type of added fly wheel, such as we ourselves use and also Messrs Lanchester. I have never been quite clear in my own mind as to the real working of this device. From one point of view it may be regarded as an inertia frictionally held fixed, relative to the crank shaft, under normal conditions, but which owing to the rapid oscillation of the crank shaft when tending to vibrate torsionally moves relatively to it and so opposes an actual frictional force to these vibrations which tends to supress them and in any case prevents their building up to any amplitude. On the other hand it may be considered as a rotating mass which with the crank shaft has a definite period of torsional vibration, but that when this period is reached the frictional connecting device slips owing to the rapidity of the vibrations, thus separating the mass of the flywheel from the shaft and causing the latter to have a different period of torsional vibration which would tend to supress the vibrations already set up under the original circumstances, so that whenever the shaft tends to vibrate torsionally its natural period is changed owing to the slipping of the fly wheel and the vibrations die out. In thinking of the device I have mostly thought of it in terms of the latter explanation. As regards your new vibration damper, two types have been illustrated over here, one controlled by laminated and the other | ||