Studies on the Seat Vibrations of Tractors (II)

Abstract

To investigate the transmissive characteristics of vibrations between tractor seat and tractor body, several outdoor experiments were done successively. The rubber materials are served as the vibration absorbing materials. Two strain-gage-type accelerometers were firmly attached to the tractor seat and the tractor body respectively. The vertical accelerations for the tractor body and seat were analyzed in terms of power spectral density (PSD) analysis quantitatively and the following findings were obtained.
1) PSD analysis exhibits that the only frequency component excited by the engine vibration could strongly affect the tractor body acceleration during running in the field which has been tilled by the rotary tiller beforehand, On the contrary, the inherent frequency component for the tractor seat acceleration, that is 2f₀, might be seen as the lower intensity component due to filter action of the vibration absorbing materials.
2) The tractor operator is perceptible of the frequency component occurred by the gravel road profile for the higher travel speed region arid hence it can deductively be pointed out to lessen the ride comfort with reference to human's natural frequency.
3) It could be discerned that slight effects for the contained frequency component were brought by power transmission system, i. e. gear backlash, un-balanced mass motion and so forth. But it is of significance to note the little effect of tire lugs.
4) The frequency response function |H(f)| shows 1 to 1.2 for the mean value and 7.8 for the peak point respectively. It can be observed that the overall tendencies of transfer function for the tractor and seat system are clear by the frequency response function.