Draw a neat sketch of ‘Locomotive coupler’ mechanism? Explain its working in brief.

Figure: Coupler Rod of Locomotive
(Link AD = Link BC = Crank Link CD = Coupling Rod Link AB = Fixed Link = Frame)
 
Working of Coupler Rod of Locomotive:
It is an example of Double Crank Mechanism in which, Links AD and BC (having equal
length) act as cranks and are connected to the respective wheels. Link CD acts as a
coupling rod and link AB is fixed in order to maintain a Constant center to center
distance between them. This mechanism is meant for transmitting rotary motion
from one wheel to the other wheel.