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).
Investigation into flywheel vibrations by systematically isolating components to determine the source.
| Identifier | WestWitteringFiles\U\August1930-November1930\ Scan129 | |
| Date | 20th October 1931 | |
| (1) Having previously found that the flywheel vibrations could be eliminated by a straight through drive from crankshaft to gearbox we tried to remove its constraining influence by inserting rubber bushes between it and the flywheel. The normal period could again be felt beginning at 2900 R.P.M. Retaining this rubber drive we removed the clutch parts to reduce the overhang of the flywheel. The maximum of the period was raised to 3375 R.P.M. but when the engine got really warm the period commenced at 2900. Running on top gear under these conditions a faint sharply defined period could be felt at 3200 R.P.M. This we think is the 2/3 torsional period due to the slipper wheels being out of adjustment. We then decided to find out whether these vibrations are due to the reciprocating masses (pistons and connecting rods), or due to the crankshaft itself. The car was therefore towed with the pistons and connecting rods absent and this was found to make no difference to the period which must therefore be caused by the crankshaft alone. Having found a small benefit (i.e. raising of the period) to be caused by less overhang, we packed out the flywheel and gearbox 1/2" from the crankshaft flange and ran the engine under its own power. The period still began at 2900 R.P.M. but was of greater duration still, being present when the valves bounced; hence we do not consider over-hang a controlling factor. | ||