Abstract: A coupling device for transmitting rotational torque in only one direction from a drive member to a driven member has first and second flange members and an elastic circular compression member. The compression member has projections on the periphery which are grabbed by claws on the flange members. There are several pairs of claws, one claw of each pair being attached to the first flange and the other claw being attached to the second flange. The first and second flanges are connected to the drive and driven members, respectively. As the drive member rotates in its only rotating direction, torque is transmitted between the paired claws via the elastic projections between the paired claws. The elastic member also has smaller projections which extend between the claws of adjacent pairs and are therefor free of compression during rotation.