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).
Letter from Studebaker discussing the inertia-operated overdrive and torsional characteristics of their engines.
| Identifier | ExFiles\Box 174\2\ img249 | |
| Date | 20th May 1938 | |
| THE STUDEBAKER CORPORATION SOUTH BEND, INDIANA WHS/LC May 20th 1938 Mr. A.{Mr Adams} A.{Mr Adams} Robotham Rolls-Royce Limited Derby, England Dear Robotham: The reason why there is no reference to the inertia-operated overdrive in the descriptions of the 1938 cars is simply that no one is using it at the present time. Just why it did not meet with popular favor is somewhat of a mystery. It did require somewhat greater care in manufacture than the ordinary overdrive, - particularly as regards the dimensions of the pawls, the spring tension on the pawls and the friction of the balk ring. By own guess however, is first that others did not receive sufficient instruction in its use to enable them to take full advantage of it and that many drivers found it necessary to alter their driving habits somewhat in order to operate in direct or overdrive as they desired. As far as I am concerned personally, I was very favorably impressed with it however, when driving the car merely for the purpose of getting somewhere, I frequently found myself in conventional gear because of the rapid depression of the foot throttle when there was no reason or desire on my part to change from overdrive. As regards the torsional characteristics of six cylinder crankshafts, we can give you no information as regards the results with a 7-bearing shaft as we have never built an engine of that type. However, we found little difference in the location of the torsional periods in the eight cylinder engine as between a five and a nine-bearing shaft and I doubt if the difference would be great in a six cylinder. Our results have never shown any indication of the fringe of the three per rev torsional period in the same type of figure as would be obtained by a three per rev torsional period at the higher speeds. This we believe to be the result of a forced vibration of the crankshaft due to inertia torque and have often had gear failures as a result of this vibration. This was particularly true when crankshafts were more flexible than they are at the present time and cast iron pistons were used. The difference | ||