Study of Adhesive Joint Strength in the Crankshaft Joints of an Agricultural Tractor Restored by Adhesion of Steel Semi-Ring Linings

To date, many methods have been developed to restore crankshafts, many of them involving the application of a layer of metal to the worn surface by weld deposition or spraying. The method of restoration of crankshaft necks of agricultural tractors by installation of welded half-rings deserves attention. Its main advantage is the minimum temperature deformation of the shaft. In this work the adhesive method of installation of semi-ring linings is tested, the relevance of which is due to the complete elimination of the temperature effect on the restored part. The purpose of this work is to study the strength characteristics of the adhesive joint 'crankshaft neck - steel semi-ring linings' under the action of tangential forces. The criterion for assessing the strength of the joint is the moment of rotation of the glued linings relative to the shaft neck. If we exclude the option of emergency scuffing, it is logical to assume that the maximum torque of resistance to crankshaft rotation occurs at cold engine start-up, i.e. at very low values of engine oil viscosity. In this work theoretical assumptions were confirmed by experimental studies, the methodology of which implied not only the determination of the torque of rotation of glued linings, but also the establishment of the influence on the strength of the glue joint of such factors as: roughness of the glued surfaces; deviation from the cylindricality of the inner surfaces of the linings; the impact of a chemically active environment; the impact of low temperatures. In order to make it possible to measure the torque of glued linings using a testing machine, prototypes were made to simulate the adhesive joint 'half-ring linings - shaft neck'. Both experimental and theoretical values of the torque of the glued linings are incommensurably higher than the maximum torque of resistance to crankshaft rotation under normal accident-free operating conditions. It has been revealed that deviations from the cylindricality of the glued surfaces have a significant effect on the strength of the glue joint.