Question

A 4-bar mechanism with all revolute pairs has link lengths $I_f=20\text{mm},I_{in}=40\text{mm},I_{co}=50\text{mm and}{I}_{\text{out}}=60\text{mm}$. The suffixes 'f', 'in', 'co' and 'out' denote the fixed link, the input link, the coupler and output link respectively. Which one of the following statements is true about the input and output links?

• A. Both links can execute full circular motion
• B. Both links cannot execute full circular motion
• C. Only the output link cannot execute full circular motion
• D. Only the input link cannot execute full circular motion

Answer 1

The correct option is A Both links can execute full circular motion

$S+L<P+Q$

In this case, the shortest link is fixed and hence, the resulting mechanism is a double crank mechanism.