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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).
Investigation into transmission rattles and the performance of crankshaft dampers.

Identifier  ExFiles\Box 138\1\  scan0033
Date  7th May 1932
  
Y634
X5310
R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}
c. to BS.{A J. Barnes - Assistant Manager}
c. to WOR.{Arthur Wormald - General Works Manager}
c. to E.{Mr Elliott - Chief Engineer}
c. to Da.{Bernard Day - Chassis Design}
c. to Ay.

TRANSMISSION RATTLES.

Replying to your R.4/A.{Mr Adams} 2. 5. 32., we do not think that the overrun gear rattles is due in any way to the half torsional period. The evidence we have for this is :-
(1) That the rattle was no worse when the crankshaft damper was absent.
(2) That fitting balance weights did not alter the rattle in speed or intensity.
(3) That the speed of the rattle was reduced from 45 to 30 m.p.h. by adding a large inertia to the propeller shaft. At the same time its intensity was greatly reduced.

Crankshaft Dampers.

If we run a car with no crankshaft damper or with the damper set at too light a load we get a bad half period but this period although bad on the drive is not detectable on the overrun. We then set the damper at a little more load than is required to eliminate the period. If we use a high damping load we are troubled with bus knocks.

Against centrifugal loading we have [struck out] that if the damping torque is correct for the half period it is four times this amount at the to- period which begins to be unpleasant some 300 R.P.M. below its peak, due to the damper being nearly solid.

Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}
  
  


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