Rubets A. Substantiation of maintenance rate of screw-thread connections of grain harvester combines

The dissertation is devoted for research of rational rate and list of operations of maintenance of screw-thread connections of self-propelled combine harvesters. On the basis of the previous field researches and analysis of literary sources the state of maintenance of screw-thread connections of combine harvesters and condition of work of screw-thread connections is reflected. The maximum state of screw-thread connection on the basis of laboratory researches according to the change of amplitude of its vibrations is grounded. The quadratic dependence of decreasing of working time to loosening of screw-thread connection when operating oscillation condition approaches to resonance is theoretical defined and experimentally confirmed. Theoretical appropriation of influence of transversal revolting forces of arbitrary amplitudes, frequencies and initial phases on working time to loosening of screw-thread connection, that allows to define the optimum parameters of screw-thread connection at the set of external influence is defined. Decreasing of torque moment of screwing up of screw-thread connections due exploitation of combine harvesters takes a place after linear dependence is experimentally defined. The rational orientation of screw-thread connection according to character of trajectory of point of contact of loosed screw-thread bar with opening of the connected details, that allows to increase of working time to loosening is grounded. The conditions of transporting of combine harvesters providing minimum external influence on screw-thread connections are defined. Rational rate of maintenance of screw-thread connections of combine harvesters of КЗС-9 and РСМ-10 on the basis of results of researches is offered. It is suggested to divide screw-thread connections into three groups according to their maintenance rate. Developed torque moment wrench and oscillation stand, protected by patents of Ukraine on useful models, can be used for researches of reliability of screw-thread connections of other agricultural machines.