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).
Experiments with different flywheel designs and extra bearings to reduce engine roughness and vibrations.
| Identifier | ExFiles\Box 182\M19\ img024 | |
| Date | 17th February 1931 | |
| -2- Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}2/W.W.17.2.31.Cont. The other light flywheel designed by W.W. (LEC.2830) is a great improvement by raising the period 300 r.p.m. (both on the road and on the test bed). This flywheel has less inertia than standard, less weight, and its centre of gravity nearer the engine. Also the disc in front to which is attached the crankshaft is considerably stiffened. On Phantom II we have tried a flywheel with an aluminium cover plate on the road. This, if anything, made the booms worse and the engine was rougher than standard. (These results were confirmed on the test bed). The fact that this flywheel of less overhang weight makes no difference, whereas a similar type on the 25HP. effects an improvement, we put down to the flywheel on Phantom II having in no way been stiffened at the crankshaft attachment. We have also tried experiments on a Phantom I engine on the test bed to find a reason for Phantom I cars booming less than Phantom II. We find the flywheel vibrates at 2200 r.p.m., runs smoothly at 2600, and again vibrates at 2800; ineach case the vibrations are small compared to those of a P.II flywheel. We again put this down to the P.I flywheel being stiffer than that on P.II. To confirm this idea we are trying a flywheel on P.II greatly stiffened at its crankshaft attachment. Extra Bearings. On the 25HP. we have tried a white metal bearing between the clutch trunnion guide and the first motion shaft. For several days this effected a complete cure of the flywheel period. The white metal soon became worn and less effective. Later a roller bearing in a similar position effected very little improvement. On the test bed a tail bearing prevented flywheel disturbance up to 3000 r.p.m. from which speed upwards vibration was present. A double bearing in front of the flywheel has been tried on the test bed and raises the flywheel period approximately 1000 r.p.m. with either a standard or lightened flywheel. We hope to cure roughness due to flywheels by use of flywheels stiffer in bending, and moved further from the crankshaft or disturbing influence. The former we are trying on Phantom II and the latter on IVG6. (Japan Unit) in 12.G.IV. Hs{Lord Ernest Hives - Chair}/H.Grylls. | ||