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).
Methods to manage crankshaft torsional periods, including dampers and stroke shortening.
| Identifier | ExFiles\Box 132\1\ scan0105 | |
| Date | 13th February 1939 | |
| 111b Rm{William Robotham - Chief Engineer}/J.R. Spooner, c. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}4/R.13.2.39. At appears that owing to the fact that our engines give a higher mean output than those of other people, we are going to have a more difficult time in removing crankshaft torsional periods by a damper. If by means of a harmonic type damper, we could run up to 4,500 revs. on the Six, we might beable to shorten the stroke in the ratio of 4 to 4.5 both on the Six and on the Eight. It appears to us that this would benefit us in two ways:- (1) As the cylinder displacement would be reduced, the impulse causing crankshaft deflection on the Eight would be reduced. (2) Owing to the increased over-lap between the pin and the journal, we might expect the crankshaft would gain in stiffness rapidly. We agree that for the Six, shortening alone would not give a great deal of relief on the shaft, because it is the piston inertia and not the firing impulse which produces the worst period. Rm.{William Robotham - Chief Engineer} | ||