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).
Engine vibration periods and the effectiveness of modifications such as dampers and additional weights.
| Identifier | WestWitteringFiles\K\October1923\ Scan2 | |
| Date | 12th July 1923 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H.D. EXPERIMENTAL REPORT. Expl. No 634 REF. Hs{Lord Ernest Hives - Chair}7/LGL.10.23. are hardly discernible under any conditions, whereas, the other extreme is to be found on the 10,000 miles production car 79-AO which has a very bad period indeed ranging from 18 to 23 M.P.H. On other cars the period is to be found at its maximum at any speed from 12 to 23 M.P.H. with varying intensity. Experiments show that the only manner in which this vibration could be effected was by making modifications to the mounting of the engine. There is no difference in engines having larger dia. crankshafts. The period is not affected in any way by friction dampers on the front end of the crankshaft. By inserting friction damping devices between the front of the engine and the frame, we were able to, on 2 or 3 cars which we have tried, to effect considerable improvement, not however to entirely eliminate it but reducing it to such an extent that we should not expect complaints from customers on this score. Another experiment was tried which consisted of adding a weight fixed to the bottom of the engine so that the engine was balanced by the centre of gyration. It was found that the addition of this weight was an improvement under all conditions but that the addition of the weight only did not eliminate all vibration periods. The following is a list of experiments carried out on one of the cars :- contd:- | ||