Ensuring the controllability of rear bearings used in the driven shaft of the KAMAZ‑5320 gearbox

Abstract

Technical diagnostics, and, particularly, automatic diagnostics of mechanical transmission units increases the reliability indicators of transport and processing machines. The technology of monitoring mechanical transmissions based on digital thermal diagnostics ensures the controllability of the diagnosed units. The unit’s adaptability to digital thermal diagnostics depends on its location, the presence of adjacent heat sources, the amount of power and kinematic loads. The controllability of the unit is ensured by determining the theoretical temperature value in the friction zone and the zone suitable for measuring the diagnostic temperature, and stating the relationship between the above temperatures. The control is carried out automatically, using specially developed software and hardware systems. To ensure the controllability of the bearing 50412 GOST 2893‑82 of the KAMAZ‑5320 gearbox, the authors determined the theoretical temperature value in the friction zone of 184.9°C during the gearbox operation in the first gear. The finite element analysis of the bearing assembly model under steady-state heat conduction determined a proportionality coefficient of 0.0812 relating the friction zone temperature to the diagnostic temperature on the bearing cap surface. As a result of theoretical and experimental studies involving thermal imaging, the temperature in the friction zone of 242.6°C was determined, indicating the pre-failure state of the diagnosed bearing. The approximate correspondence of theoretical and experimental temperatures showed the possibility of applying digital thermal diagnostics technology to the studied transmission unit. The comprehensive studies made it possible to justify the use of the digital thermal diagnostics technology and localize an area for installing a temperature sensor, namely, the bearing cover surface.