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).
Bentley chassis vibration tests concerning the torsional vibration of the frame forward of the dash.
| Identifier | ExFiles\Box 3\6\ 06-page269 | |
| Date | 20th October 1934 | |
| To E.{Mr Elliott - Chief Engineer} c. to Nor. c. to By.{R.W. Bailey - Chief Engineer} Re/FJH.{Fred J. Hardy - Chief Dev. Engineer}4/KW.20.10.34. BENTLEY CHASSIS VIBRATION TESTS. This report is additional to Re/Wym.{G. Harold Whyman - Experimental Manager}16/KW. 11.10.34. and concerns the torsional vibration of the Bentley frame forward of the dash. The tests were carried out with chassis 1-B-IV on a vibrating machine loaned to us for one day through the courtesy of Capt. Wilks, Managing Director of the Rover Co., Coventry. This machine was capable of giving impulses in a vertical direction at frequencies adjustable from 400/min. to 850/min. to each of the front wheels. The impulses were produced by out of balance weights mounted on short lengths of shaft under each front wheel. These shafts were driven by belts from a common shaft running across the machine. This method of driving the shafts was a disadvantage for torsional vibration tests because the two shafts did not keep perfectly in step, one gaining a revolution on the other approximately every 5 secs. The result was that any torsional vibration set up was damped out every 5 secs. and resonant vibrations did not have time to build up to their maximum. This made it impossible to detect accurately by eye the natural frequency of the frame etc., and it was decided to record the amplitude of the vibrations for a series of applied frequencies and to plot amplitude against frequency. The natural frequency would be shown by a peak on the curve so obtained. The method of recording the amplitude was as described in Re/Wym.{G. Harold Whyman - Experimental Manager}16/KW.11.10.34. except that the bonnet was removed. This was done as it was found that the radiator was not stationary with the bonnet fitted but was very nearly so with it removed. Attempts were made to determine the natural frequency of the Stabilisers on the vibrating machine but were unsuccessful. | ||