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).
Preliminary experiments investigating engine vibration at various speeds.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan129 | |
| Date | 4th September 1926 guessed | |
| contd :- -2- PRELIMINARY EXPERIMENTS. A standard engine was used and it was found that the most intense vibration was encountered at a speed of 3350 r.p.m., in fact so severe that fracture would certainly have resulted had this speed been dwelt upon for any length of time. Either just above or below this speed the engine would operate quite smoothly. The vibration seemed slightly worse without the slipper damper or if the friction of the dampers was insufficient. It was so severe, even with the slipper wheels, that a rev. counter could not be used on the crankshaft consequently a belt driven speed indicator had to be employed. The engine was run at full load over its entire speed range without the slipper flywheels and vibration was again encountered at a speed of 1600 r.p.m., or approximately half the previous speed, giving general roughness and gear rattle but considerably less severe than at the higher speed. The intensity could be reduced by reducing the load until it was hardly noticeable when running light at this speed. Another period was detected at approx. 1100 r.p.m. but this was even less severe than the previous one and was affected in the same way by load. Our method at this stage of detecting the vibratory periods was simply by the sound and feel of 'roughness' in the engine and even by this crude method the speeds of most acute vibrations could be fairly accurately determined. A similar test but using the slipper wheel with its contd :- | ||