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).
Stabiliser tests, comparing Wilmot and Rover models and their effects on frame frequency and vibration damping.
| Identifier | ExFiles\Box 3\6\ 06-page270 | |
| Date | 20th October 1934 | |
| -2- RE/PJH.4/KW.20.10.34. The frequencies were later determined by eye approximately by running the engine light with cylinders Nos. 3 and 4 only firing. The results were - (1) Wilmot Stabiliser 690/Min. (2) Rover Stabiliser, full weights 680/Min. (3) " " half " " 680/Min. The results of the tests on the chassis are shown on the attached Rs.{Sir Henry Royce's Secretary}1562. The frequency scale is reliable to ± 5% only as the speed had to be measured at the countershaft on the machine and corrected for the ratio of the belt drive. From the curves the frame frequency appears to be approx. 670/min. (± 5%). This frequency is increased slightly to 700/min. by fitting the lamp stiffening cross member, and the peak of the amplitude curve is flattened. With the Wilmot Stabiliser fitted there is no noticeable higher period but the lower period is rather large. This suggests too much damping in the stabiliser. With the Rover Stabiliser with full weights fitted both the higher and lower periods are present but there is again a little too much damping to obtain the minimum amplitude of frame vibration. With half weights in the Rover Stabiliser the only difference appears to be that there was more damping in the stabiliser. This may easily be so as in changing the weights the nut holding the weights to the spring may have been made tighter. The tightness of this nut must have a large effect upon the damping as it tends to prevent the leaves of the stabiliser spring from sliding as they must do when deflected. The tightness of this nut also affects the natural frequency of the stabiliser. With the nut tight the spring tends to deflect as a beam with restrained ends while with the nuts free the ends are free. This naturally alters the stiffness of the spring and consequently the frequency of the Stabiliser. | ||