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 improve engine longevity and smoothness, comparing a heavier crankshaft to a stiffer crankcase.
| Identifier | ExFiles\Box 14\2\ Scan068 | |
| Date | 26th November 1929 | |
| -17- Hs{Lord Ernest Hives - Chair}/Tuns/DG.11.29..contd. In addition to these, easy change gear boxes may shortly be forced upon us. So far, little has been done in parallel to help bearings and crankcases etc, to withstand the much increased hammering, and so we cannot expect the same life in years as the older cars gave. Rubber engine mountings can give us a false sense of security in this respect. We are inclined to favour increasing the weight of the crankshaft in preference to that of the crankcase, since this should save the bearings. If, by doing so, we can reduce the tendency of the shaft to distort and vibrate, then the bearings will be called upon to do less work. If, however, we stiffen the crankcase and suppress vibration that way, then the duty of the main bearings will be increased. Also, we find in cars like the Chrysler and Stutz which depend for their smoothness largely on stiff crankcases, that the effect of wear in the bearings is to spoil the engine smoothness and silence. We think that pure weight in the crankshaft is beneficial in two ways, (a) in that it increases the inertia resistance of the shaft, or its ability to resist vibrations under lateral alternating loads, and (b) in giving greater stiffness, lateral and torsional. With regard to the new Voisin Twin-6, it was stated in the Autocar recently that a special large crankshaft, no less than 4" in dia. (the cyl. bore is only 2.5" dia) was used, and that they claimed that the elimination of all periodic | ||