One-to-one torque coupling

A coupling comprising:

• a centre member having a main axis of rotation and including a plurality of holes disposed about the main axis at a radius;
• a left side member and a right side member, each having a common offset axis of rotation parallel to and offset from the main axis, each side member including a plurality of holes congruent with the holes in the centre member and disposed about the offset axis at the radius;
• and
• a plurality of torque transfer elements extending through the holes of the centre member into the holes of the side members,
• wherein the centre member is disposed between the side members, and the torque transfer elements rotate about a third axis parallel to and fixed midway between the main axis and the offset axis and transfer torque between the centre member and the side members through rolling contact between the torque transfer elements and the holes of the centre and side members as the torque transfer elements rotate about the third axis.