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 analysis, observing crankcase movement and the effects of balance weights.
| Identifier | ExFiles\Box 14\2\ Scan054 | |
| Date | 1st November 1929 | |
| Hs{Lord Ernest Hives - Chair}/Tem5/ADS.11.29 contd. -3- bubbles of air and oil, and could be seen slowly and clearly with the Ashdown Rotoscope. The two blocks were rising and falling on the crankcase at crankshaft frequency (as shown by the Rotoscope). No movement could be detected at the outer ends of the Blocks. We are satisfied that this movement was hogging and sagging of the crankcase produced by rotation of the shaft, and due to the fact that the two centre cranks are balanced by the cranks at either end of the shaft. We found on previous tests, that fitting the cylinder head will cure the rising and falling of the blocks, and reduce the vibration detectable at the crankcase top face, but not along the lower horizontal web. (4) Balance weights fitted. Everything else as before, i.e. bare crankshaft and flywheel back plate only. These entirely eliminated the crankcase vibration as we expected, but produced hardly any noticeable reduction in the noise inside the car, which surprised us. By feel, the engine itself was dead smooth up to the highest R.P.M. From this result that we could have very bad crankcase vibration and suppress it or not at will, and not notice much difference inside the car, we conclude that the inside of the car is most sensitive to conditions at the rear feet, which were quite smooth all the time. Hence the comparative importance of any vibration of the flywheel. | ||