Oldhams coupling

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. 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. The intermediate piece (link 4) which is a circular disc, have two tongues T1 and T2 on each face at right angles to each other.

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.

Diagram :-

When the driving shaft A is rotated, the flange C (link 1) causes the intermediate piece (link 4) to rotate at the same angle through\ which the flange has rotated, and it further rotates the flange D (link 3) at the same angle and thus the shaft B rotates. Hence links 1, 3 and 4 have the same angular velocity at every instant. A little consideration will show that there is a sliding motion between the link 4 and each of the other links 1 and 3.

APPLICATIONS:-

1. Plastic center disc possesses power for voltaic isolation.

2. It performs as a type of fuse for machinery.

3. Exert a low reactive force that fortifies the support of bearings.

4. The driving and driven shafts gyrate at similar speed.

5. There is no backlash and torsion inelasticity.

6. It behaves as an electrical insulator.

Disadvantages :-

1. Comparatively, it harbors smaller angular misalignment.

2. It possesses lower peak torque and torsion elasticity.

3. Driven and driving shafts don’t move with same speed in a single rotation.

4. There is an angular asymmetrical.

5. On the maximum note of torque, it exerts an axial reactive load on the supportive bearings.