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 nature of 'Frame Jellying', its frequency, and its relation to high-speed wobble.
| Identifier | ExFiles\Box 28\5\ Scan009 | |
| Date | 19th February 1930 guessed | |
| -2- and frequency of the mascot movement. NATURE OF FRAME JELLYING. By means of the apparatus above described, we obtained the following information :- (1) Frame Jellying is an embryo high speed wobble. (2) In consequence of this, the axle is primarily responsible for the trouble occurring. (3) Frequency of Oscillation. The maximum amplitude of oscillation, or critical period, occurs between 60 m.p.h. and 65 m.p.h. on the road which corresponds to between 10 and 11 wheel revs/sec. On the stationary test, the maximum amplitude also occurs when the impulses given to the axle by the cams on the drum are between 10 and 11 revs/sec. The actual frequency of the radiator cap movement as shewn by the records obtained is between 10 and 11 complete oscillations/sec. These three facts confirm that radiator "jellying" and "high speed wobble" are two varieties of the same disease. The front axle tries to vibrate in a criss-cross manner as in a shimmy. The shock absorbers tend to prevent this and would succeed in doing so were they attached to a rigid structure. They are not however, and the frame to which they are attached has not enough rigidity to support the dampers when they are "attacked" by the axle. Hence the frame follows the axle movement and the radiator "jellies". (4) Amplitude of Oscillation. The maximum movement of the radiator cap on 1-WJ when complained of was about .375" | ||