Oldham coupler
From Wikipedia, the free encyclopedia
An Oldham coupler is a method to transfer torque between two parallel but not-quite-collinear shafts. It has three disks, one coupled to the input, one coupled to the output, and a middle disk that is joined to the first two by tongue and groove. The tongue/groove on one side is perpendicular to the tongue/groove on the other. Often springs are used to reduce backlash of the mechanism. The coupler is much more compact than, say, two universal joints.
Named for John Oldham who invented this coupling in Ireland, in 1820, to solve a paddle placement problem in a steamship design.
The middle disk rotates around its center at the same speed as the in- and output shafts. The center of this middle disk however, moves at twice this speed in a circular motion around a center placed in the middle of the in- and output shafts.
