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 wheel wobble, or 'shimmy', as conducted by the Michelin Tyre Company.
| Identifier | ExFiles\Box 29\1\ Scan098 | |
| Date | 8th October 1925 | |
| X457 8.10.25. ANALYSIS OF WHEEL WOBBLE BY THE MICHELIN TYRE COMPANY. CONTENTS OF THE PAPER :- 1. Definition. 2. Object of the tests. 3. Nomenclature of the parts concerned. 4. Method of measuring high speed wobbles. 5. Interpretation of results. 6. Classification of tests :- * The road. * tyre. * wheel. * steering. * springs. * chassis. * unsymmetrical disposition of tyre pressure and weight (over front axle). * Out of balance. 7. Conclusions drawn from these tests. (1) DEFINITION. We have taken the term 'shimmy' invented by the Americans to indicate the often violent oscillation of the wheels on the front axle with deformation of the tyres which affects the steering of certain pleasure cars to a disagreeable extent when they are fitted with low pressure tyres (known as 'comfort' or 'balloon' tyres.) This phenomenon of which we show analysing details is distinct from the waddling or joggling wobble which was discovered before the War, and which is a sort of 'shimmy' at low speeds prompted by various causes - out of balance of the wheels etc. It should further not be confused with the phenomenon of steering shocks which are produced by contd :- | ||