Roller device for a traction mechanism drive of a motor vehicle

A roller device (10) for a traction mechanism drive of a motor vehicle, comprising:

• a roller element (12) for introducing a torque provided by the traction mechanism of the traction mechanism drive,
• a driven shaft (22) for driving an auxiliary unit of the motor vehicle, and
• a magnetic coupling (18) for non-positive torque transfer between the roller element (12) and the driven shaft (22),
• the magnetic coupling (18) includes a primary-side unit (16) connected to the roller element (12) with at least one primary magnetic element (24) and a secondary-side unit (20) connected to the driven shaft (22) with at least one secondary-side magnetic element (26),
• the magnetic elements (24, 26) are at least one of permanent magnetic or electromagnetic elements and the non-positive torque transfer is realized by the magnetic fields of the primary-side and the secondary-side magnetic elements (24, 26),
• at least one of the magnetic elements (24, 26) of the two units (16, 20) is arranged to be movable within the respective primary-side or secondary-side unit (16, 20) for changing a magnetic field overlap of magnetic fields of the primary-side and secondary-side magnetic elements (24, 26).