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).
Analysis of the factors causing steering wheel movements at high speeds on rough roads.
| Identifier | ExFiles\Box 38\1\ Scan138 | |
| Date | 26th March 1924 | |
| X3465 C.F.S. C. Hs.{Lord Ernest Hives - Chair} C. Hor. BY1-P26.3.24. STEERING WHEEL MOVEMENTS AT HIGH SPEEDS. I am of the opinion that the steering wheel movements set up when the car is driven at high speeds over rough roads are due to two distinct factors;- a/- Assuming one wheel strikes a pot hole square in centre the effect is that the axle is driven up at one side and therefore lateral movement is set up between the axle and frame - the effect on this on the castered road wheel is to turn it on its pivot to permit the lateral movement to take place, and since the arm of the moment, measured at right angles to the arm of the pivot to the point of contact of wheel with road is small, an apparently slight lateral motion between the frame and the axle turns the road wheel on its pivot through a relatively considerable angle, the forces setting up the lateral motion are very high and therefore able to easily turn the road wheel and give the effects on the steering we experience. b/- When we anchor the front axle from the rear the effect of the fore shortening action of the spring when it deflects from its normal flat portion is to try and drag back the road wheel on that side, but the inertia of the wheel prevents the wheel being pulled back. Now since the axle has to go back, but the wheel objects, the nett result is the wheel stays where it was relative to the frame longitudinally and the stub axle revolves on its pivot to accommodate the new state of affairs. c/- If we consider action a/- with near side front wheel driven up to buffer and look on chassis in plan the result is that wheels would turn so as to make a right hand turn, it is also clear that inertia effect of the wheel in b/- will result again in a right hand turn and therefore these two effects are cumulative. contd. | ||