Mechanical System Simulation involves computer modelling of mechanisms which consist of lumped mass parts, connected together via joints or stiffness elements. The system is resolved into a sequence of algebraic and differential equations using Lagrangian Dynamics. Numerical integration is applied and results are returned in the form of, displacements, velocities, accelerations, forces and graphical animations. A mechanism can be any system from a small breath actuated inhaler device to a large passenger airbus or heavy-duty crane. The lumped mass parts in MSS models can be replaced by flexible bodies generated from FE packages in order to investigate the effects of component flexibility. At present, the MSS software packages used by MVP are ADAMS (Automatic Dynamic Analysis of Mechanical Systems) and SIMPACK. Neil McGowan was former Technical Director of Mechanical Dynamics International Ltd and has 17 years experience of using ADAMS and all its modules in the industry sectors of Automotive, Aerospace, Military and General Machinery. SIMPACK is similar to ADAMS but has more extensive frequency domain and Noise and Vibration Harshness (NVH) analysis capabilities.