Eccentric orbiting type driving apparatus

An eccentric orbiting type driving apparatus, comprising:

• a casing;
• a stator fixed to said casing;
• a bearing support fixed to said casing;
• a rotary shaft rotatably supported by said bearing support through a bearing;
• a rotor fixed to said rotary shaft;
• an orbiting shaft supported eccentrically and rotatably by said rotary shaft through a bearing, said orbiting shaft having an upper end protruding out of said casing, the upper end being adapted to drive a work tool located external to said casing;
• an orbiting plate fixed to the lower section of said orbiting shaft and being disposed within said casing;
• an Oldham's ring having a protrusion, said Oldham's ring being provided between said bearing support and said orbiting plate;
• and
• grooves orthogonal to each other, said groves being provided in said bearing support and said orbiting plate, respectively, wherein said orthogonal grooves are engage with said protrusion to prevent the self-rotation of said orbiting shaft.