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).
Vibration readings taken from a 5.5' S.V. single-cylinder engine unit.
| Identifier | ExFiles\Box 134\1\ scan0111 | |
| Date | 21th November 1938 | |
| Lr{Mr Ellor}/HWS./SGL.1/CR.{Mr Cra???ster / Mr Chichester}21.11.38. 5.5" S.V. SINGLE CYLINDER UNIT. Vibration records have been taken at points on the cylinder head and crankcase of the 5.5" S.V. single cylinder engine. The results were very similar to those obtained on the 4.2" unit. There was no appreciable resonance at any particular speed. The very sharp waveform of the cylinder head vibration may lead to a certain amount of bouncing of the vibrograph stylus since the spring loading is not sufficient to follow the high acceleration of the vibrating cylinder head. The acceleration due to this sharp waveform (frequency about 25 cycles/second) is equivalent to that produced by a sinusoidal vibration of about 150 cycles per second with a marked harmonic content. It has been calculated that the vibrograph will record amplitudes up to .010" with reasonable accuracy at frequencies up to 100 cycles per second. At higher frequencies or amplitudes therefore the vibrograph will read high. Further readings were taken of these high amplitudes (.050" or more) with the vibrograph spring loading increased by about seven times. The readings were reduced about 35%. Some of this reduction was due to the whole vibrograph beginning to vibrate and the rest to the absence of bouncing. The error of the vibrograph under these conditions is thus probably between 20% and 35%. The vibration of the plug insert in this engine may be at least .050" at 3500 R.P.M. ----------> Lr{Mr Ellor}/HWS/S.G.L. | ||