This paper proposed a design procedure for one of these subsystems, which is the Wind Turbine Drive Train (WTDT). The design of the WTDT is based on the load assumptions and can be considered as the most important component for increasing the efficiency of energy generation. In industry, these loads are supplemented by expert assumptions and are extrapolated by static manipulations to calculate local load for the design of transmission elements, e.g. gears, bearings, and shafts. In contrary, in this work, the multibody system (MBS) approach is used to estimate the static as well as dynamic loads based on the Lagrange multipliers. Lagrange multipliers are numerical parameters associated with the holonomic and non-holonomic constraints assigned for the drivetrain model. The computational manipulations of kinematic stabilization, mapping the generalized forces into Cartesian respective, and implementation of velocity-based constrains into quadratic terms are carried out and the corresponding sub-routines are constructed.