| Crawler travel gear has a lot of advantages, such as good ground adaptability and passing ability, good adapting to harsh environments, small ground pressure, etc, so widely used in many fields as military, special vehicle, agricultural machinery, construction machinery and mining machinery etc. The increasing demand for coal and other mineral resources as the rapid development of national economy, continuous mining process was used in open-mit mine, which contained large crawler equipments such as bucket wheel excavator and overburden spreader. All of these make the crawler machine developed toward the large-scale, which brings many advantages such as high production capacity, costs reduction and meeting the needs of economic development and so on. However, research and manufacturing of large crawler machinery can not completely designed and manufactured by independent but depends on foreign company. Bucket wheel excavator and overburden spreader are the critical equipments in the continuous mining process. These large equipments generally use three-crawler or six-crawler travel gear because of their own high weight, turning of this travel gear was little studied. In the paper, research of steady state turning of three-crawler travel gear was done.The critical thing for solving steady state turning of three-crawler travel gear is fully understanding the interaction on the track-ground interface, but which is a complex process. In the paper, three mathematical model of steady state turning for three-crawler travel gear are established based on skid theory of the track-ground interface taking into account the shear stress-shear displacement relationship, and force analysis for single crawler, force and moment equilibrium equations of each steady state turning for three-crawler travel gear are outlined on the basis of each mathematical model. The equations are solved using numerical methods Newton iteration by mathematical software tool MATLAB. Analyzing steady state steering performance for three-crawler machinery uses solving results. So theorical analysis of three-crawler machinery is completed. Whereafter, simulations analysis of three-crawler machinery are finished by using dynamic analysis software RecurDyn. Digital model of three-crawler travel gear is built through using three-dimension software SolidWorks before simulations analysis, and which is imported into Track/LM module of RecurDyn through good interface between SolidWorks and RecurDyn. modifing digital model of three-crawler machinery and analyzing, theorical results predicted using the theorical mathematical model bears a strong resemblance to simulation results. The content of the paper is the following main sections.(1)Understanding the force analysis and calculation of large-scale crawler machinery, searching and researching study and devolopment of steady state steering analysis for three-crawler machinery at home and abroad.(2)Based on theory foundation of single crawler steering and assumption, mathematical model of steady state steering for three-crawler machinery is established. Analyzing force of each steady state steering of three-crawler machinery, outlining force and moment equilibrium equations, solving the equations through programming by using numerical technique, drawing some conclusions of steady state steering of three-crawler machinery. advantages and disadvantages of different driving mode are drawn based on two evaluation indexes, the increased rate of driving torque and sreering inaccuracy, and best driving conditions steady state steering of three-crawler machinery are proposed.(3)building digital model of three-crawler travel gear by using three-dimension software SolidWorks, importing it into Track/LM module of RecurDyn, simulating the three-crawler machinery prototype, theorical mathematical models are validated reasonable.(4)Size parameters of single crawler, track width and crawler ground contact length, and structure parameters, crawler horizontal gauge and crawler longitudinal gauge, are analyzed for the influences of steady state steering behaviour for three-crawler machinery to provide guidance for structural design of three-crawler machinery.
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