Korobko A. Scientific and Methodological Principles of Ensuring the Quality of Tractors at the Stages of Production and Operation Using the Partial Acceleration Method

This thesis work addresses an urgent scientific and applied problem of improving the quality of tractors through the creation of a tractor testing organization and methods system. Information and logistic system of metrological support of tractor testing which enables an adaptive space of production quality management to be created has been synthesized. A methodology for new testing approaches based on fuzzy cognitive maps has been formulated. The theory of assessing the theoretical evaluation adequacy and the results of field tests by using the uncertainty approach has been further developed. The method for establishing standard (nominal) values of the indicators that has been developed allows establishing their basic, limiting and permissible values for each vehicle type (in particular, for tractors) in an experimental and analytical manner. To assess the effect on the test result caused by the methodological error, the ratio of the difference between the theoretical and experimental data to the average error of their determination has been proposed as a quantitative indicator of such effect. The ratio of the measurement uncertainty of experimental data to the measurement uncertainty of theoretical data has been suggested as a quantitative indicator of the effect of random error. We have substantiated a mathematical model for measuring kinematic parameters of tractor motion when testing (linear acceleration, linear speed, angular acceleration, angular speed, instantaneous turning radius), by using linear acceleration and angular speed of the test vehicle motion as input data. The express method for testing tractor hydrostatic steering by using the partial acceleration method which has been developed allows to infer the technical condition of elements and units of its drive with no special test site available. The road brake test method of service brake systems and the parking brake system test method with equivalent load have been improved. The road working brake system test method, due to the use of new information equipment and introduction of a new performance indicator – deceleration progression gain – enables us to draw a conclusion on the technical condition of the brake system drive units and assemblies and to determine vehicle deviations in the braking process based on the test results. The recommendations for testing equipment used in parking brake system tests with the equivalent load method that have been developed contribute to improved safety of test benches. The express method developed and technological means for quality assessment of units and drive assemblies of active working elements through the tractor's power take-off shaft allow to assess their technical condition faster in the process of testing and operation and to develop recommendations regarding the need for conducting an in-depth vehicle diagnostics. An experimental and analytical method for measuring the angle of transverse stability of vehicles, while improving the safety of experimental studies and increasing the mobility of the method, has been synthesized.