Eccentric rocking type reduction gear

1:

• An eccentric rocking type reduction gear comprising:
• an internal gear;
• two external gears meshed with the internal gear;
• a crank shaft supporting both of the external gears;
• and
• a carrier rotating together with a rotation of both of the external gears,
• the crank shaft comprising first and second cylindrical cams disposed around an axial line of the crank shaft with respective phases being shifted by 180 degrees and in a manner offset from a rotation center of the crank shaft,
• both of the external gears being supported by the first and second cylindrical cams, respectively, in a freely rotatable manner and in a manner revolvable around an axial line of the internal gear,
• the carrier comprising a plurality of output pins fastened around an axial line of the carrier at an equal interval,
• each of the output pins being engaged with a plurality of through-holes provided in both of the external gears to be linked with a rotation movement of both of the external gears,
• the crank shaft being rotated as an input shaft and either one of the internal gear and the carrier being rotated as an output shaft,
• first and second eccentric holes which run in an axial direction of the crank shaft and which are in communication with each other being formed in the crank shaft,
• the first eccentric hole running from a first end face of the crank shaft to a center position of the crank shaft in the axial direction, and being disposed in a manner offset in a same direction as that of the first cylindrical cam, and
• the second eccentric hole running from a second end face of the crank shaft to the center position of the crank shaft in the axial direction, and being disposed in a manner offset in a same direction as that of the second cylindrical cam.