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 of crankshaft vibration, critical speed, and damping effects of a non-rigid flywheel.
| Identifier | ExFiles\Box 25\3\ Scan162 | |
| Date | 9th November 1926 guessed | |
| contd :- -2- resisting motion relative to the crankshaft was varied between 400 and 2000 lbs.ins. and vibration diagrams recorded between these values. Within these limits it was found that the critical speed occurred at approx. the same speed as with a rigidly connected flywheel but as the securing friction torque was reduced so was the amplitude of the vibration. A print is appended which shows a progressive re-duction of amplitude as the friction torque is decreased. These curves are reduced from the polar diagrams on to a flat crankshaft displacement base, the origin being chosen arbitrarily with respect to the crankshaft position. It is probable that this is similar to the case of the slipper wheel damper which as the friction torque was increased seemed to possess two modes of vibration - one at the original critical speed and the other at a lower speed depending on the inertia of the damper wheel. It will be remembered that as the damper friction was increased the apparent amplitude of the high speed vibration decreased, while that at the lower speed increased until the damping became virtually infinite - or the slipper wheels became solid - when the entire vibration was transferred to this lower speed due to the added polar inertia to the crankshaft. Considering this as applied to the case of the non-rigid flywheel we could imagine that this also possessed two modes of vibration - one at the observed critical speed with the flywheel rigidly connected and another outside our speed range which would reach its max. value when the flywheel became contd:- | ||