This book presents a comprehensive methodology of modeling the interaction of mechanical and hydraulic dynamics of a hydro-mechanical multi-body system using the relatively new bond graph tool. A low duty excavating manipulator with three degrees of freedom is used as a case study. Bond graph method is chosen as the modeling tool because, firstly, it is a domain-independent graphical method of representing the dynamics of physical systems. Therefore, systems from different engineering disciplines can be described in the same way. Secondly, the available literature shows that the method being relatively new, has not been thoroughly applied to model the dynamics of nonlinear systems such as excavators. The models are developed from first principles, and hence this work can be used as an educational tool on bond graphs by undergaduate and graduate students, and as a literature material by researchers. Based on the developed and validated bond graph model of the excavator, methodologies to optimize the hydraulic system design and to simulate the transient and steady-state responses of the system are presented.