Estimation of maximum lifting load capacities of a hydraulic excavator viamultibody computer modeling and simulation

A three dimensional multibody modeling of a hydraulic excavator is develope d to estimate the load capacities via computer simulation. For the modeling of the operating parts, 16 bodies are connected by the several kinematic j oints with 4 dof (degrees of freedom). And 5 bodies are connected by joints with 6 dof in the modeling of supporting and carrier parts. There are tota l 22 bodies in the multibody excavator DADS model including the ground, and the system has 11 dof including the rotation about the swing axis. To mode l the force interaction between the track and the ground, two experimental results are measured and utilized to estimate the stiffness of the spring. A four-step algorithm is developed to estimate the spring constant combinin g the force and moment equilibrium equations with the experimental results. Using the estimated spring stiffness, the maximum lifting load capacities of a crawler type excavator in various positions are calculated. The calcul ated results are in a good agreement to the experimental results before the turnover occurs and are acceptable for the design data.