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).
Flywheel vibrations in the 20 HP car model at different speeds and gears.
| Identifier | ExFiles\Box 137\4\ scan0069 | |
| Date | 20th December 1929 | |
| X634. To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Tsn. C. to Sg.{Arthur F. Sidgreaves - MD} MGT. C. to Rg.{Mr Rowledge} K.{Mr Kilner} C. By.{R.W. Bailey - Chief Engineer} HS{Lord Ernest Hives - Chair}/Tsn.1/MJ. 20.12.29. X4499 X634 FLYWHEEL VIBRATIONS. We are concentrating on this particular vibration at present, as we find in the case of the 20 HP. that it is the dominant engine vibration. In all our expl. 20 HP. cars it occurs at approx. 45 m.p.h. in third gear (3500 r.p.m.) and is the principle reason why the driver would not continue up to 50, where the valves bounce. The engine is not exactly smooth at 50, but is better than it is at 45 m.p.h. In top gear the vibration is coming on at about 57 m.p.h. It appears to be almost as obtrusive a period as the old torsional period at 3300 r.p.m., but not so noisy. Actually, with the latest stiff 20 HP. crankshaft E.55127 the top torsional period would be at 64 in third gear and 95 m.p.h. in top, much the same road speeds as in Phantom II. This of course is estimated from the half-speed periods with the slipper wheels removed, and corresponds to an engine speed of 4,400 r.p.m. With the slipper wheels removed on a 20 HP. car we could pick out all the lower periods in their correct spacing, and the flywheel period at 45 m.p.h. came just above the 2/3 rds. speed torsional period at 43 m.p.h. If the clutch inspection plate be removed, the vibration period of the flywheel can be picked out quite distinctly by eye. We have discovered that very few 20 HP. flywheels run | ||