Mechanical Engineering - Theory of machines - Discussion

A pair with point or line contact is HIGHER PAIR. Rolling action may take place with either point or line contact.

For example sphere rolling on the floor represents point contact and if one replaces sphere with cylinder then it becomes line contact.

So answer is C.

When the two element of pair have a line or point contact when relative motion takes place and the motion between two element is partly turning and partly sliding. Called higher pair Ex. - friction disc, toothed gearing, belt and rope drive, ball and roller bearing, cam and follower.

Under pure rolling no sliding form point contact. Which is higher pair.

When there is a point contact it is said to be a higher pair.

I think answer is C because there is a point or line contact between two links so it is higher pair.

Option (C) With higher pairs, the two elements are in contact at a point or along a line, as in a ball bearing or disk cam and follower; the relative motions of coincident points are dissimilar. Lower pairs are those for which area contact may be visualized, as in pin connections, crossheads, ball-and socket joints and some others; the relative motion of coincident points of the elements, and hence of their links, are similar, and an exchange of elements from one link to the other does not alter the relative motion of the parts as it would with higher pairs.

Lower pair: A lower pair is an ideal joint that constrains contact between a point, line or plane in the moving body to a corresponding point line or plane in the fixed body. A lower pair is one in which there occurs a surface or area contact between two members, e.g. nut and screw, universal joint used to connect two propeller shafts

Answer is undoubtedly D because higher pair said to be when the two bodies are contact wish other when there is partly sliding and rolling occur.

Ex:: ball bearing between two gear teeth in contact then the bodies are undergo slightly sliding and also rotating.

I think answer is C. Point or line contact between elements of pair is higher pair. Here rolling is point contact which is higher pair.