Mechanical Engineering - Theory of machines - Discussion

Yes, you are right @Rohit Tiwari.

In Belt and Pulley there are multiple point contacts.

Basically belt and Pulley is wrapping pair, but due to multiple point contacts, it is considered close to higher pair.

Belt and pulley are higher pairs as the motion is partly turning and partly sliding between them.

It is wrapping pair here we can say higher pair because,

It is in contact from sides so from that point of view it can be considered a higher pair having two line contacts.

Thanks all. But cross belt and Pulley type is higher or lower pair?

Belt and pulley is a wrapping pair when we observe closely there is no surface contact. Three ia point contact at many places so wrapping pair is close to higher pair.

Belt and pulley are lower pairs because there is surface contact. All answers are wrong.

Basically, Belt and Pulley is a wrapping pair macroscopically. But actually, there is not surface contact between belt and pulley. As there is mesh-like structure on the surface of the belt which in contact with the pulley. So there are multiple point contacts.

That's why belt drive is a higher pair.

Belt and pulley is higher pair.

Kinematic pairs can be normally classified under three headings namely, lower pair, higher pair and wrapping pair. In a lower kinematic pair, the two bodies which are connected by this pair has area contact. Suppose, we talk of two bodies, namely 1 and 2, if they are connected by a lower pair, then at this connection, body 1 will have a surface contact with body 2.

Similarly, in a higher pair the contact between the two bodies has only a line contact or a point contact. Whereas in a wrapping pair, one body completely wraps over the other. The typical example is of a belt and a pulley or a chain and a sprocket where the belt completely wraps around the pulley or the chain completely wraps around the sprocket.