Study of interference dispersion parameters in the joint of the YAMZ gearbox shaft output end and a seal

Durable operation of the “shaft-seal” joint in agricultural machines affects their service life. The analysis of factors affecting the durability of the “shaft-seal” joint has revealed the need to study the quality of the initial tension range in the “shaft-seal” joint and their compliance with the parameters of dimensional interchangeability, preset in the design documentation. The research purpose is to evaluate the probabilistic characteristics of the dispersion of joints of the inner diameter of the seal and the outer diameter of the flange of the transmission gearbox YAMZ-239. The study involved 100 flanges and 100 seals 1.2-100×125-12. The diameters of shaft ends were measured using a lever bracket SRP 100-0,001. The inner diameter of the seals was determined with a DIP-6 instrument and the NIIK-890 system. The conducted estimation of the dispersion parameters of the surface dimensions of the gearbox output shaft of YAMZ-239 under the 100h10 seal showed that shaft manufacturing provides a technological accuracy above the required level with satisfactory adjustment. However, there is a growing probability of a correctable defect. The study of the inner diameter of the seals showed that the accuracy of forming the inner diameter of the seals is good, the process adjustment is satisfactory; there is a slight shift towards a probability of an uncorrectable defect, but the defect itself is absent. The conducted analysis of tension dispersion showed that the probable percentage of defective joints, as a durability indicator, was 0.01%. The study found that the accuracy of manufacturing the “flange-seal” joint parts meets the specified requirements. The problems with the lubricant leakage from the seals should be solved based on the parameters of wear resistance of these parts, as well the wear analysis of the influencing dimensions that form a dimensional chain. In this chain, the initial closing link is the deviation from alignment and radial runout of the shaft in relation to the seal diameter.