Question

Common Data Questions:
An instantaneous configuration of a four-bar mechanism whose plane is horizontal, is shown in the figure below. At this instant, the angular velocity and angular acceleration of link $O_{2}Aare\omega =8$ rad/s $\alpha =0$, respectively, and driving torque$\left(\tau \right)$ is zero.The link $O_{2}A$ is balanced so that its centre of mass fails at $O_2$.

Which kind of 4-bar mechanism is $O_{2}AB{O}_4$?

• A. Double crank mechanism
• B. Crank-rocker mechanism
• C. Double rocker mechanism
• D. Parallelogram mechanism

Answer 1

The correct option is B Crank-rocker mechanism

Length of link,

$AB=\sqrt{(240{)}^2+(160-60{)}^2}$

$=l_{AB}=260mm$

$l_{A{O}_2}+l_{O_2{O}_4}<l_{AB}+l_{B{O}_4}$

and $O_2{O}_4$ is a fixed link. Hence it will act as a crank rocker mechanism.