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).
Vehicle suspension, tyre performance, and handling characteristics for various models.
| Identifier | ExFiles\Box 71\2\ scan0077 | |
| Date | 31th March 1926 guessed | |
| contd :- -2- (c) Such shock dampers as we tried to fit to the 20 HP. i.e. progressively increasing, small movement with no damping, and larger movement with increased effect. (6) One wonders whether the rate of vibration is the same as the wheel revolution, and therefore generated by the slightly natural eccentricity or otherwise out of truth of the tyre. This would be equally bad on a perfect road. My own observations are that with damping friction we can reduce speed until the car actually follows exactly the road surface, then it is very uncomfortable because the friction cancels the road springs entirely and the car behaves like one without road springs. This is what I believe you have to some extent at least, and what I am catering for in (5). (7) Naturally I cannot judge exactly but the 20 HP. which came here was particularly well sprung, (it had our new hydraulic shock dampers on the front) and particularly steady and free from pitching. It had however medium pressure tyres which here help materially to give a good impression. If this 20 HP. is good, the rating of the front springs is particularly high, much higher than any 40/50 four wheel brake car, or Phantom. (8) I understand that high and low speed wobbles can be avoided or rendered harmless by damping, and that our hydraulic dampers provide the most effective, reliable, and harmless way of obtaining the damping, therefore we ought to be making chassis with no wheels and dampers so that these can be fitted if proved correct, before the delivery. (9) From my experience here a car is very unsafe with tyres at 80 lbs. pressure, will not hold the road, and the shocks to the steering etc. are dangerous. The brakes are unreliable because the back wheels hop on the road. (10) Regarding different sized wheels this was never intended. The two sizes of tyres suggested for max. comfort and reputation fit the same wheels. The spares could be the smaller tyres. All I ever asked for has been agreed for the 20 HP. and I ask for a similar decision for the 40/50 as soon as the shock dampers are ready, and to be in a position to do so promptly. (11) As a means of obtaining better results in the future one thinks that in addition to (5) - (a) One might connect up the hydraulic shock dampers by a certain amount of frictionless elasticity (spring pads each side of the balls.) (b) Part of the damping can be in the steering gear - i.e. the damped pendulum lever, or an hydraulic damper on the axle with spring loaded valves (lightly contd :- | ||