Vibration characteristics of non-isolated chain saws.

The acceleration power spectra and structural resonance conditions were examined for a non-isolated medium sized chain saw. The results of the tests indicated that vibration at the frequency corresponding to the operating speed of the saw was primarily due to the fundamental shaking forces caused by the unbalanced reciprocating masses of the slider-crank mechanism and the rotating unbalance of the clutch and flywheel of the saw. The vibration response at frequencies corresponding to the harmonics of the fundamental shaking forces was amplified because their frequencies coincided with the structural resonant frequencies of the saw. Many, if not all, of these structural resonant frequencies were excited by the pulses created by the exploding gas—air mixture of the internal combustion engine. The test results indicated that the interaction of the cutting chain and wood during cutting operations contributed little to the overall vibration response of the saw.