Engineering Graphics and AutoCAD

Engineering Graphics and AutoCAD lecture notes

 

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LOCUS

It is a path traced out by a point moving in a plane, in a particular manner, for one cycle of operation.


The Cycloid

The cycloid is the locus of a point on the circumference of a circle as the circle rolls, without slipping, along a straight line.


The Involute

There are several definitions for the involute, none being particularly easy to follow.
An involute is the locus of a point, initially on a base circle, which moves so that its straight-line distance, along a tangent to the circle, to the tangential point of contact, is equal to the distance along the arc of the circle from the initial point to the instant point of tangency.
Alternatively, the involute is the locus of a point on a straight line when the straight line rolls round the circumference of a circle without slipping.
The involute is best visualised as the path traced out by the end of a piece of cotton when the cotton is unrolled from its reel.