# Various types of kinematic pair

Classification of kinematic pair

The kinematics pair may be classified according to the following consideration:

According to the type of relative motion between the elements. The kinematics pairs according to the types of relative motion between the elements are as follows.

a) sliding pair:-  when the two elements of a pair are connected in such a way that one can only slide relative to the other, the pair is known as a sliding pair. The Piston and cylinder cross-head and Guides of the reciprocating steam engine, and it’s guide is in Shaper, tailstock on the lathe bed, etc. Are the example of sliding pair. Federation will show that a sliding pair has completely constrained motion.

b) turning pair:-. When the two elements of a pair are connected in such a way that one can only turn or revolve about a fixed axis of another link, the pair is known as a turning pair. A shaft With collars at both ends fitted into a circular hole, the crankshaft in a journal bearing in an engine, lathe spindle supported in the headstock, cycle wheels turning over they are axles, etc. Are the example of turning pair. A turning pair also has a completely constrained motion.

c)  rolling pair:-  when the two elements of a pair are connected in such a way that one rolls over another fix link, the period is known as rolling pair. Ball and roller bearing are examples of Rolling pair.

d)  Screw pair:-  when the two elements of a pair are connected in such a way that one element can turn about the other by screw threads, is known as screw pair. The lead screw of a lathe with nut, and bolt with not an example of screw pair.

e). Spiracle pair:-. The two elements of a pair are connected in such a way that 1 element( with the spherical shape) turns or swivels about the other fixed element the pair is formed is called a spherical pair. The ball and socket joint attachment of a card mirror, pen stand, etc. Are examples of a spherical pair.

2. According to the types of contact between the elements. The kinematics pairs according to the types of contact between the elements are as follows.

a) lower pair:- when the two elements of a pair have a surface contact when relative motion takes place and the surface of one element size slides over the surface of the other the pair formed is known as lower pair. We have seen that sliding pair, turning pairs and screw pairs form lower pairs.

b) higher pair:-  when the two elements of a pair have a line or point contact when relative motion takes place and the motion between two elements is partly turning and partly sliding, then the period is known as higher pair. A pair of friction disc toothed gearing, belt and rope drives, ball and roller bearing and cam and follower are examples of higher pair.

3. According to the types of closure. The kinematics pair according to the types of closure between the elements are as follows,…

a) self closed pair:- when the two elements of a pair are connected together mechanically in such that only required kind of relative motion occurs.m, it is then known as self closed pair. The lower pair are self-close pair.

b)  force- closed pair:-  when the two elements of a pair are not connected mechanically what are kept in contact by the action of external force, the pair is said to be a force closed pair. The cam and follower is an example of force closed pair, as it is kept in contact by the force exerted by Spring and gravity.