Third inversion of Double slider crank chain :
Oldham’s Coupling
An Oldham's coupling is used for connecting two parallel shafts whose axes are at a small distance apart. The shafts are coupled in such a way that if one shaft rotates, the other shaft also rotates at the same speed.
This inversion is obtained by fixing the link 2, as shown in Fig (a). The shafts to be connected have two flanges (link 1 and link 3) rigidly fastened at their ends by forging. The link 1 and link 3 form turning pairs with link 2.
These flanges have diametrical slots cut in their inner faces, as shown in Fig.(b).
The intermediate piece (link 4) which is a circular disc, have two tongues (i.e. diametrical projections) T1 and T2 on each face at right angles to each other, as shown in Fig. 5.36 (c).
The tongues on the link 4 closely fit into the slots in the two flanges (link 1 and link 3) The link 4 can slide or reciprocate in the slots in the flanges.
