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).
Tests to eliminate engine vibrations and booms in the 20/25 HP car model.
| Identifier | ExFiles\Box 137\4\ scan0117 | |
| Date | 21th November 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/AJL. c. to SS.{S. Smith} BOT. c. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to Hy.{Tom Haldenby - Plant Engineer} 20/25 HP. CAR ENGINE VIBRATIONS. we have carried out tests to try to eliminate the engine booms which are apparent on most 20/25 HP. cars. We find that by disconnecting the torque reaction dampers we can frequently eliminate the boom which is otherwise apparent both on forward and over-run conditions between 48 and 53 M.P.H. We have found that cars which suffer badly from this one particular period have either excessively loaded torque reaction dampers or else the Ferodo friction discs have got into a very gummy state and require a much bigger load to start them slipping than the load required to keep them slipping. Torque reaction vibrations are very bad if no dampers are used at all. Various friction disc materials have been tried with a view to finding one that will damp out the large amplitude low frequency torque reaction vibrations and yet not transmit the high frequency vibrations at this high speed. The material which gave the best results was the Cotton 'A' fabric that we use for servo linings. The best results were obtained from this after it had been soaked in engine oil for twelve hours; the | ||