kinematic link based on relative motion between links

1)Sliding pair.In a sliding pair minimum number of degree of freedom is only one.

2)Turning pair.In a turning pair also degree of freedom is one.when two links are connected such that one link revolves around another link it forms a turning pair.

3)Cylindrical pair.In a cylindrical pair degree of freedom is two.If one link turns and slides along another link it forms a cylindrical pair.

4)Rolling pair.In a rolling pair degree of freedom is two.The object moves both linearly and angularly.

5)Spherical pair.In a spherical pair degree of freedom is three.It can both move left and right,up and down,and rotate along the same point.

Based on nature of contact.

1)Lower pair.If contact between two links is surface contact also having degree of freedom one,then the pair is known as lower pair.Example: Sliding pair.

2)Higher pair.If contact between two links is either point contact or line contact then the pair is known as higher pair.Example: Point contact-Rolling pair.Line contact-Cylindrical pair.

3)Mechanical pair.

(a)Open pair.In this pair everything is open to the atmosphere.

(b)Closed pair.In this pair everything is closed from the atmosphere.