ASSESSMENT OF LOW-FREQUENCY VIBRATION LEVEL ON THE TRACTOR OPERATOR'S SEAT

The article considers the methods of reducing low-frequency vibration (LFV) of a machine-tractor unit (MTU) and sanitary standards for the vibration level of the tractor driver's workplace, provided that active wind protection devices are used. The object of the study is a MTU based on a class 0.6 tractor. LFV was reduced by changing the rigidity and drag coefficient of the seat and wheels of the tractor, taking into account their influence on the level of vertical vibrations on the operator's seat. The process of movement of the sprung seat is considered under the condition that the input process is the displacement of the cabin floor, and the output process is the displacement of the mass loading the seat, equivalent to the mass of the tractor driver. The reduction of low-frequency random vibrations was assessed taking into account the difference in the frequency of the predominant vibration of the seat base and the natural frequency of the seat. Schemes of displacement of the cabin floor of an equivalent mechanical system with the determination of the frequency response of the tractor driver's seat for different values of the relative attenuation coefficient have been developed; The vibration system of a tractor in the longitudinal-vertical plane was analyzed, with the dependence of the variance of the vertical displacement of the tractor seat on the deformation of the rear axle tires and the stiffness coefficients being determined. The spectral density of the vibration of the seat base was constructed. A system of equations was obtained describing the motion of this model in deviations from the static equilibrium position; the initial data of the tractor base were used to determine the variances of the change in the angle of inclination of the longitudinal axis of the tractor and the vertical coordinate of its center of gravity. The ranges of variation of the drag and stiffness coefficients were considered. Based on the calculated data, graphs were constructed showing the dependence of the angle of inclination of the tractor in the longitudinal plane and the variance of the vertical displacement of the center of gravity during longitudinal vibrations on the drag and stiffness coefficients of the front axle.

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