Gear device

A gear device for transmitting torque, at a predetermined reduction gear ratio, between a pair of partner members mutually coupled relatively and rotatably via a main bearing,

• the gear device comprising:
• an outer cylinder which can be fixed to one partner member;
• a plurality of internal gear pins which are mounted along an axial direction of the outer cylinder on an inner peripheral face of the outer cylinder;
• a carrier which is housed inside the outer cylinder and can be fixed to another partner member;
• a crank shaft which is supported rotatably by the carrier;
• and
• an oscillating gear which is supported by the carrier so as to oscillate in conjunction with the rotation of the crank shaft, and which includes external teeth enabled to engage with the internal gear pins, wherein
• a plurality of pin grooves extending in the axial direction of the outer cylinder are formed on the inner peripheral face of the outer cylinder, and the internal gear pins are fitted in the pin grooves,
• the pin grooves are formed so that a length of the pin grooves becomes longer than a length of the internal gear pins, and
• the carrier is configured to regulate movement of the internal gear pins and the oscillating gear in the axial direction.