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).
Engine vibration, with a quote on crankcase vibrations, and the arrangement of counterweights on crankshafts.
| Identifier | WestWitteringFiles\T\November1928\ Scan123 | |
| Date | 13th November 1928 guessed | |
| contd :- -8- We ran through the main period once, when the engine was again smooth. This top period was not serious, and we believe could have been damped out. With a S/C. and increased engine torque such might not be the case. The periods on this car were typical, being in their usual speed relationship; they were sharp and well defined, but quite smooth on either side. The engine could be driven up to and beyond the main period with no indication of its nearness. The steering box was attached partly to the crank-case, so vibration would have been instantly perceptible. Confirmation of our opinions is afforded by H.M. Crane, Technical Assistant to the President of General Motors, who said in a recent article on Engine Characteristics - XXXXX "When the speed increases the crankcase springs under the increas-ing loads so that vibrations are produced directly in the crank-case which are very serious in amount and distinctly unpleasant to the driver" - also - "In many cases in the past the performance of a particular make of engine has been limited by undue vibration caused by a flimsy badly supported shaft" - also - speaking of 6-cyl. engines : "They must to a certain extent be balanced locally whether they have 3, 4, or 7 bearings". ARRANGEMENT OF COUNTER WEIGHTS. Figs. 2 and 3 shew how the counter weights are placed on some crankshafts in other cars. The principle appears to be appreciated more in America than elsewhere, possibly because of the amount of research they do; practically every new model pro-duced there recently, whether 6 or straight-8 is so fitted. Contd :- | ||