The aim of this thesis is the study of a midi Excavator Hydraulic Circuit through the new 3D mechanical library in Simcenter Amesim®. First of all, a description of the excavator classifications, as well as the load sensing working principle will be illustrated, with the explanation of the hydraulic components used on these types of hydraulic circuits. After that, it has been modelled the real excavator created in SolidWorks® given by the FPRL into Amesim® with two element types of this mechanical library: Rigid body and Recursive joints, this latter is able to take into account the inertia transfers from one body to another, useful because the inertia depends on the positions of each element that compose the excavator arm, but also from the load that the bucket has when it is full after dig.