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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).
On car engine vibrations and 'booming', particularly in the P.2. model, detailing diagnostic telegrams and proposed solutions.

Identifier  ExFiles\Box 137\4\  scan0313
Date  12th April 1931
  
E.{Mr Elliott - Chief Engineer} HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce}
BY.{R.W. Bailey - Chief Engineer} (At Le CanadelHenry Royce's French residence.)

8634
R1/M12.4.31.

C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} RG.{Mr Rowledge}

CAR ENGINES - PRINCIPALLY P. 2. AND BOOMING.

Since my last memo. on the above I have returned to my earlier impression that the car engine, especially P. 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 two faults then an experimenter would be deceived because modifying 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 CANCEL-"LING 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 centreing 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 would expect some move-
  
  


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