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 three recorded failures of the low inertia damper spring plate.
| Identifier | Morton\M9\ img040 | |
| Date | 24th August 1931 | |
| To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Ry. c. Wor.{Arthur Wormald - General Works Manager} Mx.{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey}/AD24.8.31. X.634. X.5010. LOW INERTIA DAMPER - SPRING PLATE FAILURES. Rv6/Gll.8.31. The total number of failures to date appears to be three. (1) On production test, which failure was decided to have been due to faulty erection. Afterwards an alteration in design was made to prevent this occurring and in addition machined rivets were substituted for countersunk headed screws for holding together the two halves of the driving centre and the spring plate; the object of this was to lessen the possibility of the spring plate becoming loose in the driving centres. (2) In the Exptl. Dept. one failure occurred on an engine which had been run under abnormal conditions, i.e. crankshaft vibration experiments at very high speeds. Owing to the abnormal conditions, the breakage was not considered of importance. (3) In service one failure has occurred, and examination of the broken piece clearly indicates that the spring plate had been loose between the driving centres ( As this was an early car, screws were fitted, not machined rivets). There is also evidence to the effect that the engine was bad for period vibrations some little time before the breakage was discovered. The owner does not habitually indulge in high speeds, he says that he has only on three occasions tried the car for maximum speed when he says he did 110 M.P.H. on less than full throttle. All the evidence in this instance appears to point to the loose spring plate being the initial cause of loss of correct slipping load and ultimately of the breakage, but we have not any evidence to show that the car was driven for any time at high speeds on a crankshaft period. We think this is purely an isolated case and do not anticipate a crop of troubles of this type, at the same time it is evident that even when using machined rivets, this part is not over-strong for what it has to do, viz. take inertia forces due to braking, end thrust due to helical timing gears and possible end movement of the crank under torsional forces. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} | ||