Each pink pedal is attached to pink triangle-shaped conrod of a parallelogram mechanism of three cranks (in orange and violet).
Violet shaft is fixed to the violet crank. The shaft rotates on two green bearings. Yellow wheel is connected to the violet shaft via a freewheel (not shown) placed inside the rim hub. Three crank concept helps the parallelogram mechanism overcome its dead positions.
The pedals rotate around a virtual axis. The pink circles are their trajectories.
Disadvantage of this drive in comparison with a chain one: its transmission ratio is 1. So it’s necessary to use a gear box placed in the rim hub for increasing speed.
STEP files of this video:
http://shrtfly.com/CPOjZ
Inventor files:
http://shrtfly.com/UJfG6nX
credit by Thang010146
