Mathematical Modeling of Threshing Rate on John Deere Combine (Model 1165)

Thresher performance in combine harvester is evaluated with two parameters: threshing (percentage of threshed grain to the total input grain to thresher) and separating (percentage of separated grain in threshing space to total threshed grain). Modeling of threshing rate makes possible estimating of threshing loss. Threshing and separating are stochastic events. In this research، a stochastic mathematical model was developed for threshing rate. This model uses an exponential function as probability density function (pdf) to describe the threshing rate with varying feed rate، thresher speed and grain moisture content. Based on data from field experiments، threshing rate was determined. Its range varied from 2. 627 to 3. 821 in different conditions. Using nonlinear regression of SPSS، coefficients of model achieved with R2=0. 72.