Question

In a four-bar mechanism for the position shown, the velocity of the crank is 1 rad/sec (CW). The angular velocity of the coupler link BC is

• A. 0
• B. 6/5 CCW
• C. 5/6 CW
• D. 5/6 CCW

Answer 1

The correct option is D 5/6 CCW

In the figure the instantaneous centers are shown in the figure below.



$AB=crank,\omega =1rad/sec$

BC = coupler

The instantaneous center $I_{13}$ lies at C

From Kennedy theorem,

${\omega }_2\left(I_{23}{I}_{12}\right)={\omega }_3\left(I_{23}{I}_{13}\right)$

$\Rightarrow 1\times 5={\omega }_3\times 6$

$\Rightarrow {\omega }_3=\frac{5}{6}\left(CCW\right)$