PURPOSE: To transmit a power to an industrial machine such as an injection molder which requires a large power and control the driving of the machine.

CONSTITUTION: A flywheel 50 is provided on the one end of an input shaft 60 and a planetary gear mechanism which is composed of a ring gear 30, a sun gear 32, planet gears 34,... is provided on the other end. The power of the fly-wheel 50 is directly transmitted to the sun gear 32 of the planetary gear mechanism through an electromagnetic clutch E. On the other hand, coils C and C' whose winding directions are opposite to each other are applied to the outer circumferences of drums 20 and 20' which are made to rotate in the directions opposite to each other by the flywheel 50. The one side ends of the coils C and C' are retained with speed change gears 24 and 24' which are driven by a control motor M and the other side ends are retained with driving wheels 28 and 28' which are linked with the ring gear 30. Output shafts 70 and 70' are made to rotate by the planet gears 34,... which are made to circle by the ring gear 30 and the sun gear 32.