Machinery & Energetics

Principles of design of the agricultural machine movable operating parts shall be based upon physical, chemical and process mechanical properties of the agricultural materials, which they interact with during operation. One of the main parameters of the dispersed agricultural materials is the coefficient of friction between them and the surface of the movable operating part. The soil is considered to be the most difficult agricultural material to study. The complexity of the study is conditioned by a complex structure as the soil is a heterogeneous system containing solid, liquid and gaseous phases, as well as living organisms. Moreover, phase to phase ratio may vary with time. Modern bibliographic sources provide extensive coverage of the studies in the field of the frictional interaction between two solid-state bodies. At the same time, the issue of the interaction between the solid-state body and dispersed medium, in particular with the real soil material still remains undiscovered. As it follows from the study, three types of friction (sliding (kinetic), rolling, as well as combined rolling and sliding one) occur simultaneously during operation within the area of contact between the movable operating part and soil. A corresponding dependency is established in consideration of all possible types of friction to determine the overall coefficient of friction between the surface of the tilling machine movable operating part surface and soil. The Kolmogorov equation system has been developed to provide the option of determining all probabilities in respect of values of coefficients of friction between the surface of the tilling machine movable operating parts and soil as time variables.

coefficient of friction, movable operating part, soil, sliding, rolling, tilling machine