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).
The failure of a Phantom II low inertia slipper wheel during testing.
| Identifier | Morton\M19\ img105 | |
| Date | 21th January 1931 | |
| ORIGINAL To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Da.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to Rg.{Mr Rowledge} By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KT.21.1.31. X634. P.II. LOW INERTIA SLIPPER WHEEL Whilst carrying out the test to determine the critical speed on the crankshaft with 2.125" pins on 19MX{John H Maddocks - Chief Proving Officer}, the engine became very rough. Examination of the slipper drive showed that the low inertia plate had failed at the point where it is clamped between the two driving pieces which pull up on the taper of the crankshaft. The failure did not appear to be due to shearing the plate by torsional oscillation, (in any case it is difficult to imagine how any load sufficiently large to accomplish this could act on the plate), because it was not possible to move hub Y more than a small amount rotationally (2° or 3°) relative to the plate X. Our own opinion is that the plate was broken due to a form of "whirling" of the slipper wheels similar to that we used to experience sometimes on the old type slipper wheel which would move sufficiently far to touch the wheel case. In this instance the taper on the shaft has picked up, which might accentuate the trouble if it happened before the plate broke. It was noticeable that the driving springs had dug into the face of their guide at A.A. and that this can happen we are in favour of the shaft drive suggested by E.{Mr Elliott - Chief Engineer} for the new low inertia wheel. We have had a second low inertia slipper wheel fail on production test in a similar manner to this one and for this reason consider it is worth bringing to your notice. We consider the failure of this damper may be responsible for the high figure obtained for the critical speed on the small pin crankshaft reported in our Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}2/KT.15.1.31. and that in consequence we may find on repeating the tests that the large pin crank has an advantage in master period. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||