Working principle:

At the initial position, the air-gap is 3mm between copper rotor and permanent magnet rotor. When the motor rotates, the copper ring of copper rotor cut the magnetic field lines of permanent magnet,generate inductive eddy current and creates a magnetic field in copper rotor. Between the two fields,there is force which is not only transfer torque between the motor and work machine, but also transfer the axial force between sub-rotors. Compared with the speed slip between copper rotor and permanent mangnet rotor, the air-gap is from 3mm to 5mm for achieving better soft-start.
When the work machine suddenly overloaded or stuck in the case, the speed of permanent magnet rotor decreased rapidly, or reduce to zero immediately. But, the speed of the motor and the copper rotor almost the same, due to the axial force between sub-rotors enlarge the air-gap till max. Thereby reducing transmitted torque between the copper rotor and the permanent magnet rotor till a small value.And, even the load exceeding a certain limit value, the motor is fully protected

Technical advantage:
Few day-maintenance,low operation cost, almost maintenance-free products
Accept misalignment, centration error 5mm (max), angular error 2 (max) 。
With overload protection, increase overall system reliability, eliminate the damage of system for overload. When the loading is in normal, the system automatically return to working or can be directly re-start.
Improve the motor starting capability and come true the motor soft start / stop. Specially, suitable for big torque, high inertia loads.
Reduce shock and vibration, coordinate between multi-machine-driven load distribution.
Simple structure, small size, easy to install, adapt to work in harsh conditions.
Extend the life of the transmission system components.