Dependence of the operational reliability of a cutter-loader on the magnitude and character of the load

The work done by a cutter-loader between repairs is governed by the quality of its manufacture and by the size and character of the load. One of the main causes of breakdown in cutter-loaders at the face is fatigue fracture of an element in the drive to the cutting head, due to power losses in the reducing gear and motor (shaft drive). According to the theory of a gradual thermally activated process with exhaustion of operational capacity (strength), the power expended in the drive determines the development and accumulation of dislocations and microfissures in the components and also the wear of the surfaces in contact. These factors determine the service life of the machine. Therefore the rate of expenditure of power in the drive (the power loss) is one of the principal indices of the quality of the machine, determined in bench tests on cutter-loaders at the Leningrad Mining Institute (LGI). The drives to the cutting heads and loaders of cutter-loaders undergo rapidly varying loads. Investigations have revealed that the total power loss in the reducing gear and motor of the cutter-loader is made up of static and dynamic components. Our investigations lead to the following conclusions. 1. In designingmore » and using cutter-loaders, we must remember that their operational reliability is inversely proportional to the rate of power consumption in the machine drive, and this depends practically linearlyon the load oscillation frequency. 2. The power losses in the drive of a cutter-loader are determined by the static and dynamic components of the loads and depend on the distribution of the resistive torque between the screw conveyers. 3. In bench tests on assembled cutter-loaders before they are dispatched to the pit, the load imposed should be equal in frequency, mean level, and nonuniformity to the operational load.« less