Internal gear set having roller teeth

An internal gear set comprising first and second gear members, the first gear member having n identical cylindrical rollers in slightly oversize semi-cylindrical pockets formed in its radially outer face and equally spaced along a circle, the center of which is the axis of the first gear member, and the second gear member having n + 1 identical cylindrical rollers in slightly oversize semi-cylindrical pockets formed in its radially inner face and equally spaced along a circle having the axis of the second gear member as its center, n being an integer greater than 2, the first gear member nesting within and axially offset from the second gear member to provide expanding and collapsing chambers between the gear members upon rotation of one gear member relative to the other, each roller being free to move radially except to the extent that such movement may be restricted by its pocket and by rollers of the other gear member, and the diameter of each roller exceeding the spacing between adjacent rollers of the other gear member.