Assessing design and manufacturing quality of tractor gearboxes by their vibration characteristics

The paper deals with the development of a vibration-based technique for assessing quality and detecting design and manufacturing defects of tractor gearboxes. It highlights full-scale experimental studies of vibro-diagnostic characteristics of tractor gearboxes including carrying out vibration measurement and spectrum analysis; identifying statistical limit values of structural vibration parameters and their dependence on the technical condition of tractors; and comparing the vibration characteristics with acceptable vibrations which do not affect the acceleration of the process of tractor gearbox wear. All studies were conducted for tractor gearboxes of wheeled tractors T-150K, KhTZ-170, and T-17221 produced by Kharkiv Tractor Plant and equipped with identical tractor gearboxes of the same manufacturer. It has been determined that the vibration levels of gearboxes at the manufacturing stage exceed the acceptable vibrations by 10–30 dB. The main reason for the accelerated development of faults and decrease in the lifetime of most gearbox mechanisms is an increase in vibration loading by 2.5–31.6 times over the acceptable levels. The practical significance of the results obtained is in solving the problem of improving the design and manufacturing of tractor gearboxes T-150k through the use of the developed criteria for permissible vibration by methods of reducing the vibration level of detected defects. All the above mentioned makes it possible to create a complex of normative and technical, and methodological documentation to improve the reliability of tractors.