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).
Continued memo on the investigation into the causes and remedies of steering wobble, termed 'pit-pat', in the Phantom model.
| Identifier | ExFiles\Box 28\4\ Scan311 | |
| Date | 21th August 1925 guessed | |
| contd : -2- the steering being sufficiently quickly deflected. We are now fairly satisfied that we know the nature of the phenomenon sufficiently well for us to try the remedies suggested. It will be seen that it is difficult for us to do anything in the way of altering the periodicity of the axle what may be known as the 'criss cross' period between the axle and the road surface. So far as we know also gyroscopic forces do transfer the rise and fall cross-ways of the axle - termed 'pit-pat' into the wobble. We do not know if this gyroscopic action is the real and only connection between the vertical and horizontal movement of the wheels. It was suggested by E.{Mr Elliott - Chief Engineer} that the car could be run on bumps on the dynamometer, but it has since occurred to me that we might run on absolutely smooth dynamometer wheels and produce the tendency of wobble without-of-balance wheels, and controlling the chassis with suitable wire ropes and possibly tension springs. We might be able to watch the phenomenon quite closely and very conveniently get a cinematograph upon it. At the moment we have no reason to believe that the lateral flexibility of the high centre of gravity, or extra weight of the 'V' series (Phantom) have any bearing on the matter, but this we hope will be definitely proved within the next few days. The extra speed of the Phantom has caused it to be more often found. At the moment we understand the trouble can be definitely avoided by balance kept within 1/4 lb., tyre pressure of 50 lbs. per sq.in. or over, and front shock absorbers effectively tightened (within limits this latter is definitely an advantage for other reasons, especially on Goshawks.) R.{Sir Henry Royce} | ||