This model demonstrates how a moving drive train modelled with 3-dim. multi-body elements (revolute, bodyCylinder) can alternatively be modeled with component rotor1D to speed up simulation. The movement of the two systems is identical and also the cut-torques in the various frames (such as: r1.frame_b.t and r2.frame_b.t).
The driving joints (r1, r2) with rotation axis {0,1,0} are modelled to be driven by a motor torque along the {1,0,0} axis. Basically, this means that an idealized bevel gear is used to drive the axes of the revolute joints.