Patent ID: 8162789

Claim:
A reduction gear box comprising: a rotation direction converting unit that comprises a first pedestal including a first flat face, an input shaft supported rotatably in the first pedestal, an intermediate shaft supported rotatably in the first pedestal in a position substantially orthogonal to the input shaft, a first gear that rotates integrally with the input shaft, and a second gear that meshes with the first gear and rotates integrally with the intermediate shaft, wherein the input shaft is adapted to detachably couple to an output shaft of a motor independent of a meshed state of the first and second gears; and a reduction unit that comprises a second pedestal including a second flat face making surface contact with the first flat face, an internal gear, an external gear housed within the internal gear, and a crank shaft supported in the second pedestal, the crank shaft configured to rotate with respect to the second pedestal and be incapable of moving in its axial direction, the crank shaft having an eccentric cam that engages with the external gear and causes the external gear to revolve orbitally in the internal gear by revolving eccentrically; wherein the rotation direction converting unit and the reduction unit are joined together, by being fixed while the first flat face and the second flat face are in a state of making surface contact and in this positional relationship the intermediate shaft and the crank shaft are coupled such that they are configured to transmit torque and the intermediate shaft is configured to move in an axial direction of the crank shaft, wherein the rotation direction converting unit, the reduction unit and the motor are configured to be detached from each other without changing the meshed state of the first and second gears of the rotation direction converting unit and a configuration of the reduction unit, and rotation generated by either the internal gear or the external gear with the rotation of the input shaft is transmitted to an output rotation member.