This thesis studies the prototype of a coaxial Planetary Magnetic Gearbox (PMG) developed at Politecnico di Torino, combining experimental tests with the development of a dynamic Simulink model to perform simulation analysis. The PMG consists of two pairs of magnetic wheels acting as the sun and the ring of an epicyclic gear, and a set of ferromagnetic poles, acting as the planets, that can shift between the two wheels passing through a neutral position. After introducing the main advantages of magnetic gears technology, comparing it to their mechanical counterparts, the focus shifts to the description of the working principles of the PMG and its dynamic modelling.