# [Theory of Machines] Why is Belt in a Belt drive a Link...

by nanunath
Tags: belt, drive, machines, theory
 P: 69 Hello every1... I'm a mechanical enggineering student... I've been studying theory of Machines... My academic syllabus includes only "Simple Mechanisms"... Now in Simple Mechanisms...the first thing we get to know is a "Kinematic Link"... Definition of a Kinematic Link:-it is a rigid or resistant body having relative motion with respect to other link/elements of the machine/mechanism But I just dont get how a belt in a belt drive[and chain in a chain drive ] is link... because if I stand on a single part of a chain I'll find the other parts moving[except for the ones in a straight line moving in a particular direction]...and these individual parts of the chain together form a chain[same should apply for belt drive...with a very large number of individual parts..I think] Moreover I also dont get how Belt-pulley forms a higher pair... Lastly is it a part of "Complex Mechanisms"... Plz help me ... any ideas on this are welcome... Thanxxxx
 P: 69 Any Idea...anyone...?? Any ideas are welcome...Please do post if you have any idea... Have I posted it in the Wrong section..and so not getting any help?? Which section should I post it in?? [Actuall I found "Conceptual evaluations" as tag for the sub section title ... and so posted it here]
P: 733

## [Theory of Machines] Why is Belt in a Belt drive a Link...

Belt/chain drive is not regarded as a single link, they make what is known as a higher pair, & it is considered as an equivalent to two lower pairs(or kinematic link).

Belt pulley is a higher pair because it has line contact & no slippage(ideally)
P: 69
 Quote by ank_gl Belt/chain drive is not regarded as a single link, they make what is known as a higher pair, & it is considered as an equivalent to two lower pairs(or kinematic link). Belt pulley is a higher pair because it has line contact & no slippage(ideally)
Thanxx...
 Belt/chain drive is not regarded as a single link
That did solve my confusion...
and
ya..they do make a higher pair...
But can u tell me where can I find[or can u give/write] me a document which explains how the "Chain-Sproket" Kinematic pair results in a constrained motion with a single Degree of Freedom...

any help appreciated...
P: 733
 Quote by nanunath But can u tell me where can I find[or can u give/write] me a document which explains how the "Chain-Sproket" Kinematic pair results in a constrained motion with a single Degree of Freedom...
what are the possible relative motions between a chain & a sprocket?

Hint: chain cannot slip on the sprocket

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