Power transmitting device

A power transmitting device comprising

• a first transmission member,
• an eccentric rotating member that is formed by integrally linking to each other a main shaft portion supported so as to be rotatable around a first axis and an eccentric shaft portion positioned on a second axis eccentric to the first axis,
• a second transmission member that is disposed adjacent to the first transmission member and is rotatably supported on the eccentric shaft portion, and
• a transmission mechanism that is provided between the first and second transmission members,
• the transmission mechanism being formed from a hypotrochoidal first transmission groove and an epitrochoidal second transmission groove that are formed in one and the other of opposing faces of the first and second transmission members and a sphere that carries out transmission of torque between the first and second transmission grooves while rolling in the two transmission grooves,
• wherein the first and second transmission grooves are formed so that each of the transmission grooves and the sphere make contact via two contact points, and a locus of the contact point on an outer side of a bent portion of each transmission groove has a minimum radius of curvature that is set to be larger than ½ of a distance between the two contact points of each sphere.