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 balance weights and flywheel vibrations on a 25 HP engine.
| Identifier | ExFiles\Box 181\M13\M13.2\ img073 | |
| Date | 22th July 1931 | |
| X.5010. X.634. ORIGINAL To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to SS.{S. Smith} Wor.{Arthur Wormald - General Works Manager} c. to EA. E.{Mr Elliott - Chief Engineer} c. to Hy.{Tom Haldenby - Plant Engineer} Ha/Gry.{Shadwell Grylls}2/MJ.22.7.31. 25 HP. BALANCE WEIGHTS & FLYWHEEL VIBRATIONS. We have previously tried balance weights on 16-G4 to eliminate the flywheel vibration, and have shewn that as the effectiveness of the balance weights is increased the flywheel period is reduced. The weights on that occasion balanced about 90° of the crankshaft. With all twelve weights we noticed a definite decrease in amplitude of the vibration. Six of the weights only was very little improvement on no weights at all. We have now tried on a car fitted with the big pin crankshe twelve weights balancing the crankshaft and big end. This car was fitted with a standard flywheel. In this case the flywheel vibration was entirely absent, the engine being smooth up to the torsional period at 3900 - 4000 R.P.M. These weights were of the large mass type; the total weight of balance weights being nearly 30 lbs. By using this type we only lowered the torsional period another 200 R.P.M. by balancing the big ends in addition to the crankcase. The torsional period with twelve weights to Sch.1402 tried on 16-G4. was at 4200 R.P.M. The crankshaft designed for 'Japan 111' could certainly have twelve full balance weights and a torsional period above 4500 R.P.M. Judging by the smooth running obtained during this last experiment, it would seem worth while to balance all the centrifugal forces and hence at the same time the two couples inherent in the six cylinder crankshaft. Certainly going the last step and completely balancing the centrifugal loads appears to give more result than going the first step i.e. balancing the crank only. Hs{Lord Ernest Hives - Chair}/H.Grylls. | ||