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).
Engine dampers, harmonics, and the consideration of a pendulum-type damper for a 6-cylinder engine.
| Identifier | ExFiles\Box 132\1\ scan0159 | |
| Date | 29th April 1940 | |
| -2- Rm{William Robotham - Chief Engineer}/JRS.3/JS.{Mr Johnson's Secretary}29.4.40. of an engine is a direct multiple of the engine speed and, therefore, the restoring force of the mass 'm' must vary with the square of the engine speed and this is done by making the restoring force depend upon centrifugal force instead of springs. The main disadvantage of this type of damper is that it will only handle one harmonic and the number of harmonics causing trouble require an equal number of dampers. However, in our 6-cylinder engine our main worry is the third harmonic which a Lanchester or damped harmonic type of damper of reasonable size will not handle very satisfactorily, and the pendulum type is worthy of further consideration for this purpose. Rm{William Robotham - Chief Engineer}/JRS. FIG 1 DISTURBING FORCE M FIG 2 DYNAMIC MAGNIFIER RATIO DISTURBING FREQ. / DAMPER FREQ. WITH DAMPER WITHOUT Rm{William Robotham - Chief Engineer}/JRS. | ||