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).
Fitting a harmonic bumper to the Phantom III to control frame oscillation and shimmy.
| Identifier | ExFiles\Box 96\1\ scan0377 | |
| Date | 15th March 1939 | |
| 2. BY/SB.{Mr Bull/Mr Bannister}1/MG.15.3.39 (continued) (7) We have fitted a harmonic bumper specially designed for the Phantom III. This is a most marked improvement in controlling the torsional oscillation of the front end of the frame. It is to Drawing PD. 383, except that we have used only three horizontal spring blades, instead of four as drawn. The periodicity with four blades is much too high to have any appreciable effect. Whilst we do not think that all the foregoing is essential, we propose to leave the car alone now as we shall not be able to improve upon it. So far as other similar cases are concerned, the most important feature is undoubtedly the fitting of the harmonic bumper, which we think should be made standard on any future Coupe or Sedanca bodies. The question of the weight distribution will of course have to be treated individually. We think a harmonic bumper, in conjunction with solid mounting of the six forward body brackets and the scuttle fixing, will deal effectively with the Coupe shimmy on any other Phantom IIIs. BY/SB.{Mr Bull/Mr Bannister}B | ||