Evaluation of Tractor Quality Based on Vibration Characteristics

Abstract

Problem. The overall development time for agricultural tractors is 7-10 years, with testing accounting for approximately 63-80% of the total time. Within testing, reliability testing under operating conditions comprises 58-73% of the workload. However, even after extensive testing, serially produced tractors often fail to meet the specified lifespan and reliability requirements. Final refinements are only made to tractors after a certain accumulation of operational faults, resulting in hidden defects remaining in the serial production of tractors, as testing primarily addresses major structural and manufacturing defects. Goal. The aim of this study is to evaluate the design and manufacturing quality of tractors based on their vibration characteristics. These characteristics can identify structural and technological defects that decrease the reliability and lifespan of tractors. Methodology. Analytical research methods were employed to improve the quality of traction electric motors for electric transportation. Experimental research methods and the determination of electric motor technical conditions based on their vibrodiagnostic parameters were utilized. Statistical methods were employed to process experimental studies. Results. Vibration measurement results indicated that tractors belonging to vibration class E are not recommended for serial production. These tractors have an estimated lifespan of 6-8 thousand engine hours and incur high maintenance costs compared to tractors of vibration class D. Tractors with vibration levels of class E are not recommended for serial production due to the excessive vibration load on components. Originality. The T-150K tractor family requires significant redesign of its structure, manufacturing processes for components, and bearing unit assembly. This is achieved through constructive measures, such as ensuring bearing preload in shaft supports, using class 4 precision bearings with a noise index of QE1, and providing a floating fit with a clearance of no more than 15 μm between the bearing and the housing. Introducing intermediate bushings into the design of gearbox output shaft bearings improves the accuracy of machining bearing seating surfaces and the assembly of bearing units. Practical value. The developed vibration evaluation methods for T-150K tractors enable the assessment of their design and manufacturing quality. The research data obtained during the design stage allows for more reliable predictions of tractor quality.