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 low-frequency engine vibration, its potential causes, and recommendations for further investigation using different instruments.
| Identifier | ExFiles\Box 124\1\ scan0268 | |
| Date | 27th November 1939 | |
| -2- RM{William Robotham - Chief Engineer}/JRS.12/JH.27.11.39. but this is not marked on the curves. This might either be due to some effect of the stroboscope or to a vibration of the engine and the brake at a frequency at which the responce of our instrument is low. This low frequency vibration has been noticed previously and has a harmonic in the vacinity of this speed and in order to investigate it further in the future it would be advisable to either design a new Summer's type torsiograph with a low natural frequency and to make use of an electrical type of pick up in conjunction with the Cathode Ray oscillograph. In the latter case it would have the added advantage of being applicable to use on the road and so eliminating the complication of studying a mixture of two modes of vibration of which only one is of interest to us. The breakage of clutch centre plates during the endurance run of B.60 No.1 may have been caused by this low frequency oscillation also, but on the other hand it may have been due to misalignment of the bed. From a study of the torsiograms, I see no reason why this engine should have any trouble due to torsional oscillation on the road especially if the maximum r.p.m. are limited to 4,000. RM{William Robotham - Chief Engineer}/JRS. | ||