Chapter 7

Relative vels in Slider Crank Mechanism
The velocity of the slider A (i.e. v A) may be determined by relative velocity method as discussed below : 1. From any point o, draw vector ob parallel to the direction of v B (or perpendicular to OB) such that ob = v B = \u03c9.r, to some suitable scale, as shown in Fig. 7.5 (b). 2. Since A B is a rigid link, therefore the velocity of A relative to B is perpendicular to A B. Now draw vector ba perpendicular to A B to represent the velocity of A with respect to B i.e. v AB. 3. From point o, draw vector oa parallel to the path of motion of the slider A (which is along AO only). The vectors ba and oa intersect at a. Now oa represents the velocity of the slider A i.e. v A, to the scale. The angular velocity of the connecting rod A B (\u03c9AB) may be determined as follows: vBA ab \u03c9AB = = (Anticlockwise about A) AB AB The direction of vector ab (or ba) determines the sense of \u03c9AB which shows that it is anticlockwise.