Olieinikova O. Increasing indicators of the road-holding ability of a motor-grader

The dissertation is devoted to the solution of an actual applied science problem of increasing the indicators of road-holding ability of a motor grader which is reached at the expense of clarification of the methods for determining parameters of movement trajectory while carrying out technological operations. It has been experimentally established that the movement trajectory of the motor grader can be formed in different ways: the linear movement trajectory of the motor grader is formed due to the working resistances on the blade which have relatively small values and in such cases, deviation of the actual movement trajectory of the motor grader from the planned one is not registered; in situations where the value of the adhesion coefficient of the wheels to the bearing surface is negligible, the movement of the motor grader while performing technological operations on a curvilinear trajectory is fixed; in the process of cutting the soil, a piece-linear movement trajectory of the motor grader is fixed while the machine initially moves straight. Then, as the external resistance increases, it stops, rotates around the locking point of the blade blockage and then continues to move straight. The dynamic model of a motor-grader has been improved, the analysis of the impact of operation indicators of the working process on road-holding ability of the car has been made. The movement of a motor-grader can be objectively and comprehensively described by two dynamic schemes and corresponding mathematical models: the mathematical model of the flat motion of the machine in the bearing plane under the action of external forces; the mathematical model of the machine rotation relative to the locking point of the blade blockage under the action of external forces. The condition of transition from the car flat motion to turning relative to the point of the blade blockage has been specified. The mathematical model in which different types of technological operations performance are taken into account; cutting, beam scheme; layer-by-layer scheme; soil shifting, is improved. The analytical dependences of the forces acting on the motor grader for determination of components of the main vector of external resistances depending on the developed environment and the type of the performed technological operation is clarified. The proposed numerical model of soil prism formation in front of the blade during the movement of the motor grader within the technological operation demonstrates that the interaction of the excavating part with the environment changes at the second movement stage: the area of the cut chips decreases; during the rotational movement around the point of the blade blockage not the whole prism of the previously accumulated soil moves, but only a part of it. It is substantiated that the geometric parameters of the working process have a significant influence on the indicators of road-holding ability of the motor grader, they determine the position of the working body in space during the operations of soil digging and the coordinates of the application of the main vector of external resistance forces. The formation of the movement trajectory of the machine is determined by the action of dynamic loads on the blade and the impact of the variable on the way of the digging resistance force. The developed dynamic model allows to predict the movement trajectory of the motor grader with a tolerance of not more than 11%. A system for stabilizing the trajectory of a motor grader by adjusting the wheels inclination has been developed and patented. Rational parameters of lateral displacement have been determined, at which the deviation from the rectilinear trajectory will not exceed ± 0.1 m.