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).
The objectives and probable causes of wheel shimmy, based on tests conducted on a Renault L.S. 1923.
| Identifier | ExFiles\Box 29\1\ Scan099 | |
| Date | 8th October 1925 guessed | |
| Contd :- -2- blows due to the inequalities of the ground on the steering and which are all the more accentuated when the steering is very light and tyre approaches low pressure proportions. (2) OBJECT OF THE TESTS. Numerous factors exercise influence on the start, the sustaining and the elimination of the phenomenon. We do not know them all - we will consider as important: Road, tyre, springs and steering. The object of our tests is to study the part played by each of these items. In order to do this we have sometimes altered one of the factors and left the others constant, some-times, on the other hand, we have altered several items at once. The majority of the tests have been carried out on a single type of car - the 12-HP. Renault L.S.1923, whose characteristics are as follows :- RENAULT DETAILS OMITTED. The tests have not allowed us, up to the present moment, to give satisfactory explanation of the phenomenon in question, or to suppress by simple and rational means wheel shimmy on every type of car. They have thrown light however on the probable causes of shimmy and we enumerate them in their order of importance :- 1. The lateral instability of the low pressure tyre which facilitates rolling movement and promotes the start of a shimmy. 2. The faculty of storing up and giving out energy is greater for a low pressure tyre than that for a high pressure tyre. 3. The steering reversibility and its connection with the front wheels by an elastic system of levers and steering rods which help to maintain and build up wobbles. contd :- | ||