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).
Report page discussing crankshaft stiffness, inertia calculations, and test results for various engines.
| Identifier | ExFiles\Box 25\3\ Scan321 | |
| Date | 29th April 1928 guessed | |
| -3- Contd. a main journal with the bearing omitted. Fig.6 shows the result of the test, on the centre journal of a 20 H.P. We also did a test to show the effect of bevelling the outer extremities of the webs, as shown on the Stutz drawing, Fig.5. We found on one of our own shafts that this made 3.6% reduction in stiffness, and so would nearly cancel the reduced inertia. We had one example of a 4-bearing 6-cyl. engine to deal with, in a Lorraine-Dietrich car. As we were unable to apply your formula directly, we added a few terms to make it cover the two types of double crank in this shaft. The resulting expressions for the equivalent length are shown in Fig.7. We obtained agreement in this instance between test and calculated stiffness of within 1%. In fig.8 we give a comparison of calculated and observed periods on some engines. These were all calculated from measured values of stiffness and inertia except the Stutz. We had the stiffness and dimensions of this shaft, and had to calculate the inertia. We have calculated the inertias of the standard 20 H.P. and Phantom crankshaft, from the drawing, to within about 5% of the measured values. We shall shortly investigate the crankshaft torsional period on our F.XI. aero engine, and shall communicate the results to you. We have several stiffer crankshafts designed for our car engines, based on the results with your formula, but | ||