The purpose of the work is to accurately calculate the forces acting on the working mechanism of wheel loader when excavating granulated material. In order to examine mobile machines movement processes, MSC.ADAMS is used to carry out multi-body system simulation and hydraulics sub-system simulation. Because the flexibility of the component of the working mechanism of wheel loader can not be neglected, ANSYS is used to compute the data describing the behaviour of the flexible component of working mechanism of wheel loader. Based on the Fundamental Earthmoving Equation, this paper describes a methodology and basic formulations of forces between the tool and the material to be moved as well as the internal forces in the pile to be dug from. The method has been implemented in an MSC.ADAMS model of a working mechanism wheel loader. The numerical simulation test on LCM(Linyi Construction Machinery) Wheel Loaders under various position of working equipment will be done to predict the forces acting on the machines during digging cycles.