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).
Investigating the source of vibrations and booming in the P. 2. car engine, detailing telegrams exchanged and theories regarding the flywheel and torsional damper.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan112 | |
| Date | 12th April 1931 | |
| E.H.S.) FROM R.{Sir Henry Royce} DY.{F R Danby} ) (At Le CanadelHenry Royce's French residence.) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} RD. R1/M12.4.31. CAR ENGINES - PRINCIPALLY x634. P. 2. AND BOOMING. Since my last memo. on the above I have returned to my earlier impression that the car engines, especially R.{Sir Henry Royce} 2., can be definitely improved at the source of the vibrations. I asked Derby some time ago to put the power unit on the test plate and examine it carefully to see if the periods were at the same speed as found on the car. I have not heard anything. I feel certain that since they are periods they are more than the natural impulses due to torque reaction and variation in the kinetic energy in the pistons. If there were 2 faults then an experimenter would be deceived because modifying one does not remove the booming. The following telegrams were therefore sent: " REGRET COMPLAINT REPORTED PROMISE REASONABLE SATISFACTION CANNOT " HAVE ANYONE UNHAPPY. HAVE RETURNED TO BELIEF OF CURABLE FAULTS IN " UNIT PROBABLY FLYWHEEL FLUTTER AND INSUFFICIENT TORSIONAL DAMPER. " DOUBLE FAULTS ARE MISLEADING PRESENT STANDARD ENGINE MOUNTING WITH " THICKER RUBBERS WILL THEN BE SATISFACTORY BUT GEARBOX SUPPORT BETTER " ALSO RUBBER MOUNTED - REPEAT DERBY AND WITTERING. " " UNCONVINCED UNIT FAULTLESS PROBABLY DOUBLE DAMPER FLYWHEEL SHOULD BE " INCREASED AND MAIN FLYWHEEL LIGHTER STIFFER AND EXTRA SUPPORT BY " DOUBLE BEARING OR FROM GEARBOX AS TWENTY. ACCEPT POSSIBLE ERRORS OF " ALIGNMENT BY CANCELLING BOTH UNIVERSALS - REPEAT WITTERING. " My first idea was that the rubber coupling did not keep central and was whirling. It should be fitted with metal centre-ing bushes or steel plate, or cancelled altogether for test. The second idea was that our torsional damper was set with insufficient friction or the damper had not enough inertia to allow for sufficient damping. This might be cured by centrifugal loading or increase in the constant setting with every possible fraction of weight added to the rim. Naturally one must expect some movement or the damper cannot damp but it is possible that the movement is excessive - i.e. it is letting the shaft vibrate torsionally over a great range. One would not expect much benefit from balance weights; they might make matters worse - i.e. like a weaker shaft. On the test plate the angle of oscil- lation should be watched and measured, and I think it will be found to agree with one of the troublesome speeds. If not, then it must be the flywheel. Mr. Ricardo says that with several engines this has been a very persistent fault over a great range of speeds, and very difficult to alter. Apparently he introduced the double bearing after trying all other methods of supporting. (1) | ||