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).
Torsional vibrations in a slipper wheel's steel disc and related engine performance issues.
| Identifier | ExFiles\Box 13\7\ 07-page083 | |
| Date | 1st February 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.) Copy to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} P. 2. LOW INERTIA SLIPPER WHEEL. X.634. X.7480. X.5770 The breakage of the steel disc I think shews that the crankshaft shortens and lengthens during the torsional vibrations. I conclude that it is nothing to do with either the whirling of the centre of the crankchamber or the whirling of the flywheel or slipper wheel, but is entirely connected with the master period. That could be very fairly easily tested by running the engine at constant speeds increasing from the harmonics to the whirls, and from the whirls to the master, examining the condition of this disc in its mounting after each run, until we find the distressing speed. I am not sure that increased rigidity will be found good but we may try it. I am more inclined to ask for the friction surfaces to follow the disc by making them both like the flexible one and springs on each side. The rigid side may only need slight flexibility of say .050. I do not know any other way of catering for the trouble. It is to be hoped that it only occurs at the master period and that no one but ourselves ever run their engines on master periods. This rather supports my anxiety that our cars are too low geared, if they are fitted with 11/41 axles, which should only be used with bodies that will prevent the car getting away beyond 70 MPH. And I have now got the impression that the smooth speed range of the 6 cyl. engine is more limited than most of us have been in the habit of thinking. Fortunately our overspeed is also past our best power which is difficult to get beyond 2500. I have not before me the revolutions of best HP. we are getting from Japan 1. or expect to get from Japan 3., but suppose it is well over 3000 - i.e. a double 6 made from 2 Japans should not only be happy at higher revs. than P. 2. but will be maintaining its power. I am also now pressing for double top on Japan 3., available by click on the steering column and raising the accelerator pedal; it will be worth the cost. R.{Sir Henry Royce} | ||