| Resulting from lack of modern design theories and methods in the past, the designers drew and calculated with certain blindness by manual and often cause a long term and low efficiency and dependence on the model machine, it's difficult to meet the demands of serialization and diversification and rapid update of the products. Working device is an executive mechanism and its design is the important part of the loader design. Superior or inferior performance of the working device will directly influence the behavior and efficiency and costs of the product, and even competitiveness and market share.For further improve working performance and efficiency of the model ZL50G loader, developing optimum design on working device of the ZL50G based on kinematics and dynamics simulation and verified the optimum design results based on finite element analysis and experiment.The main contents and fruits are the following(1) Giving an overview of actuality and development tendency in the future according to the loader and working device at home and abroad, put forward the aims and the tasks of this article based on the questions exist in the working device researches at present.(2) Introducing the composition and characteristic features, design parameter and performance index, typical operation conditions and design requirement and design methods of the six bar mechanism.(3) Established simulation model of the working device apply ADAMS software, researched the change regularity affected by design variables in common restriction:Max. bucket back angle and its position lie in level and full lift of the boom; max. force ratio of the mechanism lies in ground close-by, min. force ratio lies in bucket back position at ground close-by and full lift dump position; max. unit lifting torque of the boom cylinder lies in ground close-by, max. angle and min. angle between the bucket and the bar lie in bucket back at ground close-by and full lift dump position separately; min. length of the tilt cylinder lies between bucket back at ground and boom level position; researched sensitivity on parallel, force, dump and transmission and so on according to single parameter and multi- parameter from qualitative analysis and quantitative analysis aspects, we can see that performance change tendency is linear when the design variable in small range from the simulation curves. Programing comprehensive optimum design of LW500K working device based on the above researches.(4) Applying finite element analysis software ANSYS on optimized LW500K working device, analyzed boom stress distribution in central loading and partial loading conditions, the results showed that partial loading condition is the main reason that boom failure; compared with the model, the weight of designed boom plates reduced to 776kg by 8%. Testing on the model and 1000 hours strengthen experimentation together with National Construction Machinery Quality Supervision and Inspection Center.The results of finite element analysis and tested showed that an obvious improvement on working performance and operation efficiency and lightweight design of the boom plate is feasible.
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