Oldham’s coupling
Oldham’s coupling is used to connect two shafts which are not in alignment but their axes are parallel. The coupling consists of two flanges (A & C) which are keyed to their respective shafts. The inner faces of flanges are grooved. In between the two flanges, a cylindrical piece (B) is fitted as shown in figure. There is a tongue running across on each face of cylindrical piece. The rotary motion from flange A to flange C is transferred via cylindrical piece. The cylindrical piece rotates and slides in between the two flanges when the two flanges rotate.
The velocity of sliding for the cylindrical piece is given by
v = ωr
Where v = velocity of sliding
ω = angular velocity of shaft
r = distance between the axes of two shafts