Determining vertical oscillations of front-plow tractor without support wheel

Abstract

The object of this study is a tractor with a front plow without a support wheel. One way to avoid the use of ballast is to use front-mounted plows that operate under the "push" mode. As a rule, such plows are equipped with at least one supporting wheel. The presence of the latter complicates the structure of the plow and, of course, affects the degree of vertical load on the steered wheels of the mobile vehicle. With the help of the constructed mathematical model and the corresponding amplitude and phase frequency characteristics, the dynamics of vertical oscillations of the front axle of a tractor with a front mounted plow without a support wheel were investigated. Vertical fluctuations of the total force acting on the tractor from the side of the plow were considered as a disturbing influence. According to the simulation results, an increase in the vertical load of the front axle of the tractor by 600 kg causes a desired decrease in the value of the amplitude and an increase in the phase of external disturbances of the dynamic system. The higher the frequency of disturbance oscillations, the more acceptable these characteristics become. It was established that in order to improve the response of the studied dynamic system to disturbances, it is necessary to reduce the stiffness coefficient of the tires of the front wheels. In practice, this is achieved by adjusting the air pressure in the tires. The amplitude-frequency characteristics of the system almost do not change when the damping coefficient of the tires of the front wheels of the tractor is increased in the range from 1 to 3 kN·s/m, while the phase-frequency characteristics improve. This is especially noticeable at the frequencies of oscillations of the disturbing influence in the range of 0–10 s-1. The results could be used as a basis for evaluating the efficiency of tractors with a front plow without a support wheel in tillage operations. Such efficiency can be achieved under the condition of practical implementation of the recommendations proposed in this paper regarding the selection of design parameters of tires for the front wheels of the tractor