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).
Crankshaft vibration testing, comparing a stiffer crankshaft to a standard one and detailing future tests.
Identifier | ExFiles\Box 25\3\ Scan144 | |
Date | 18th September 1926 guessed | |
contd : -6- We expected a larger reduction than this and think that perhaps removing the tops of the pistons does not give an accurate com-parison with respect [illegible] to the weight effect because of the absence of the ring friction and probable air cushioning, all of which would tend to reduced the inertia impulses on the crankshaft. We shall check this effect of weight more accurately another time. STIFFFER CRANKSHAFT. One feature of the stiffer crankshaft we have demonstrated is that not only is the critical speed raised approx: 270 RPM, for an increase in stiffness of 12% but the amplitude of the vibration is reduced at the critical speed and the lower full load vibratory speed. The amplitude measured from the diagram is now 6° at the critical speed instead of 8 3/4°. Diagrams are shewn on the attached print of the full load vibration with the standard and stiffer crankshaft for comparison. It will be noticed that the speeds at which these dia-grams are taken are slightly lower than given in the previous report. These speeds are those which gave the greatest amplitude to the vibration and are slightly lower than we found before using the recording apparatus because of the inertia of the plate carrying this apparatus which we bolt to the crankshaft. We next intend to test a Silver Ghost for vibrations and determine the efficiency of the slipper wheels. At present we are measuring the torsional rigidity of the Phantom crankshaft and will do the same for the Silver Ghost. Hs{Lord Ernest Hives - Chair}/A.C.Lovesey. | ||