It is named so because of its resemlance to a grasshopper’s hind leg.
Input: pink bar turning +/-40 deg.
Point E of green bar traces a vertical nearly straight line (in blue).
AB = BC = BE
To get the blue line straighter increase DC while keeping the trajectory of point C (in green) as near as possible to the horizontal line.
Here
AB = BC = BE = 30
DC = 60
Distance AD in vertical direction: 59.8
Distance AD in horizontal direction: 52
The video last part shows full trajectory of point E.