Washing machine driving system and a washing machine with the same

A washing machine driving system comprising:

• a motor comprising a rotor frame;
• and
• a planetary gear assembly comprising:
• a carrier shaft connected to a drum shaft,
• a first fastening member that couples the carrier shaft to a back end of the drum shaft and supports the carrier shaft and the drum shaft,
• a coupling shaft that is supported by the carrier shaft, the coupling shaft comprising (i) a first shaft portion inserted into the carrier shaft and (ii) a first flange portion fixed to a back end of the carrier shaft,
• a second fastening member that couples the first flange portion to the back end of the carrier shaft,
• a carrier that is supported by the coupling shaft, the carrier comprising (i) a second shaft portion inserted into the first shaft portion and (ii) a second flange portion disposed at a back side of the first flange portion,
• a sun gear that is rotatably coupled to the coupling shaft and supported by the rotor frame of the motor,
• a third fastening member that couples the sun gear to the rotor frame,
• a plurality of pinion gears coupled to the second flange portion of the carrier, the plurality of pinion gears being tooth-coupled to the sun gear,
• a ring gear that is tooth-coupled to the plurality of pinion gears, and
• a gear housing that accommodates the sun gear, the plurality of pinion gears, and the ring gear.