Selection of the analytical dependency for assessment of slipping of the Kirovets K-7 wheeled agricultural tractor

BACKGROUND: The accuracy of prediction of towing properties is related to selection of the analytical dependency for assessment of slipping in the process of development or modernization of agricultural tractor in order to define the correct configuration of a machine-tractor unit. The relevance of the study lies in justification of the dependency describing slipping of wheels of modern high-powered 4K4b tractors and needed for study of tractors’ towing properties.

AIMS: Justification of the analytical formula of slipping for better accuracy of towing properties prediction at development stages and modernization of 4K4b tractors and units conjugated to them.

METHODS: Known analytical dependencies of slipping were analyzed in the study in order to compare the theoretical assessment results with the results of field-testing at harvest field carried out at machine testing stations according to common method. The theoretical and experimental results were obtained for the Kirovets K-7 series agricultural wheeled tractors. The experimental data of the Kirovets K-7 series tractors was approximated in order to find new dependencies for analytical determination of slipping at harvest field. The approximation coefficient was taken as the criterion for assessment of accuracy of experimental data description by the dependencies.

RESULTS: Among the considered analytical dependencies for prediction of slipping coefficient value, the equations which describe the experimental data of towing testing of the Kirovets K-7 series tractors the most satisfactorily were outlined. Based on approximated experimental data, the equations of slipping depending on specific towing force were obtained. There is the equation common for all tested tractors and there are separate equations for tractors with 32-inch and 38-inch tires. These equations provide with the best approximation of description of tractors. Values of specific towing force correlating to maximal towing efficiency and acceptable slipping coefficient of 16% for the Kirovets K-7 series tractors were obtained.

CONCLUSIONS: Some existing and new proposed in the article equations can be used for prediction of values of slipping coefficient at creating of potential towing characteristic for high-powered 4K4b tractors.