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 steering geometry, including wheel cant and pivot inclination, in relation to vehicle stability and shimmy.
| Identifier | ExFiles\Box 29\1\ Scan109 | |
| Date | 8th October 1925 guessed | |
| contd :- -12- angle so that the tendency to shimmy will not be increased. It is not much use aiming at anti-castoring which increases the tendency of the steering to take charge and renders a hair-pin bend and ruts dangerous on the road. Angle between wheel and vertical. The angle between the wheel and vertical increases the stability of the car, reduces the wear of tyres on bends, and gives sweet steering. In this particular it favours shimmy. In reducing the angle of the wheel cant, other things being equal, one increases the re-action in the pivot arises, and therefore makes the steering heavy. It follows that one reduces shimmy but the result is only a simple verification. Therefore, it is better, being given actual speeds, to maintain a certain wheel cant on the car say 2º to 4º. Inclination of the pivots. This made its appearance with front wheel brakes. It reduces the disturbing effect which these may in certain cases convey to the steering. It gives sweetness to the steering and greater stability after a bend. The pivot axis generally meets the ground on the inside of the car, with reference to the plane of the wheel, at 20 to 30 mm. from the centre of the elliptical tyre pad of contact. In altering the inclination of the pivots to zero we have reduced shimmy. This is not astonishing seeing that we have at the same time increased the stationary resistance and made the steering heavier. However, we have not proved that more or less inclination of the pivots plays an important part. We consider that in the ordinary way the pivot axis contd :- | ||