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).
Analysis comparing Stutz engine crankshaft vibrations on the road with those of the 20 HP model.
Identifier | ExFiles\Box 23\5\ Scan071 | |
Date | 8th February 1928 | |
To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} RG.{Mr Rowledge} c. to BY.{R.W. Bailey - Chief Engineer} OY. 44336 STUTZ ENGINE VIBRATIONS. We have been carefully comparing the Stutz crank-shaft periods on the road with those of the 20 HP. The engine has now run about 5000 miles and so may be considered quite free. On the whole, considering that the crankshaft has no damper, these periods are remarkably unobtrusive. The main period, which occurs at about 3800 engine r.p.m. is not in the same category as that of a 6-cyl. engine. It is not very easy to separate the noise of the main period from that of the valves bouncing on the Stutz as the two occur quite close together, and there is practically nothing in the way of vibration even on the pedals to indicate that the period is taking place, the noise only can be heard, and this is not very alarming as it gives the impression of very high frequency but small amplitude. As a rough estimate we should say that this main period is very little worse than the undamped half master speed vibration of the 20 HP, and might be dealt with successfully by means of a torsional damper. As will be seen from the attached data, this fits in quite well with the anticipated results, because on an 8-cyl. the inertia torque is insignificant and at these high engine speeds the gas torque is not sufficiently great to cause serious trouble. The half master period vibration which occurs at 37-38 m.p.h. on top gear has a very small range, the duration being only 1+ m.p.h. and is so slight that it cannot really be detected unless the car is being driven at something contd :- | ||