From the image it seems to be a regular pull-lever crossbow, and [i]not[/i] a crank-operated one? A crank-operated crossbow would be a cranequin crossbow, I'd assume... (As far as I know, the first indeed predated the latter ... by maybe half a century to over half a dozen centuries, depending on what regions to take account of - I found allegedly confirmed instances of pull-levers from the 5th century, whereas the cranequins were not really around before 13-14th century or so, now that I'm trying to find some information. Might be a better question for Legion, though I am not sure how much this falls under his part of history.)
Ehh... But I may be rambling; it just seemed that there was a slight discrepancy between the descriptions and the image provided.