KINEMATIC PAIR
*Two links (or) elements of machine when in contact with each other are said to form a pair.
*If the relative motion between them is completely (or) successfully constrained, then pair is known as "Kinematic Pair".
1. Sliding Pair
When one element of pair can only slide relative to the other, then the pair is known as "Sliding Pair".
Ex: Piston and cylinder, Tail stock on lathe bed.
2. Turning Pair
When one element of pair can only turn (or) revolve about a fixed axis of another link, then pair is known as turning pair.
Ex: Lathe spindle supported in head stock, Wheel turning over the axle.
3. Rolling Pair
When one element of pair rolls over the other link, they are said to be rolling pair.
Ex: Ball and Roller Bearings.
4. Screw Pair
When one element of pair can turn about the other by screw threads, the pair is known as screw pair.
Ex: A bolt with nut
5. Spherical Pair
When one element having spherical shape turns about the fixed element, then the pair is called sherical pair.
Ex: Ball and socket joint.
6. Lower Pair
If the two elements of a pair have a surface contact when relative motion takes place and surface of one element slides over the surface of other, then pair is known as lower pair.
Ex: sliding pair, Turning pair, Screw Pair.
7. Higher Pair
If two elements of pair have line (or) point contact during relative motion and motion is partly turning and partly sliding, then pair is known as Higher Pair.
