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).
Notes on steering, detailing the analysis of two types of wheel fight observed during testing.
| Identifier | ExFiles\Box 170\3\ img013 | |
| Date | 25th February 1936 | |
| C O P Y. NOTES - STEERING. Feb. 25th/1936. Wheel Fight on rough roads. Experience in testing wheel fight on T.W. Chevrolet using road test and cams on the bump rig. Cams used: 4" x 3/4" 9" x 1" 18" x 1" ("Washboard" cams). 9" x 1" appear best - not quite so violent as the washboard cams. An attempt to interpret our results would be as follows :- (1) Two types of wheel fight. Under suitable conditions one gets on the cams two distinct wheel fights at 400 cycles/min. and 550 cycles/min. respectively. The first type is essentially wobble of the wheels with shake of the car and engine; in other words, it is close to a low speed wobble. The second is essentially hopping of the wheels with an excitation of wheel fight which is almost certainly gyroscopic; i.e., it is closely related to shimmy. (Note: these are not actually pure wobble or shimmy which are produced on smooth surfaces. They should rather be regarded as a tendency to wobble or shimmy which may not show up on the road. See my notes of June 5, 1935). These two varieties of wheel fight have been seen so often on all types of suspension and occurring always at very nearly the same two frequencies, that we are forced to conclude that they are basic tendencies on all cars. | ||