This is a model of the mechanical part of one cylinder of an engine. It is similar to Loops.Engine1a. The difference is that a simple model for the gas force in the cylinder is added and that the model is restructured in such a way, that the central part of the planar kinematic loop can be easily replaced by the assembly joint "Modelica.Mechanics.MultiBody.Joints.Assemblies.JointRRP". This exchange of the kinematic loop is shown in Loops.Engine1b_analytic. The advantage of using JointRRP is, that the non-linear algebraic equation of this loop is solved analytically, and not numerically as in this model (Engine1b).
An animation of this example is shown in the figure below.