When I was designing robots back in the late '60's and early '70's, there were all sorts of people (academics, designers, engineers, and kooks) working on anthropomorphic machinery, with extension to animal forms as well as human. With the passage of time I have forgotten most of these proposals, but, seeing this picture, called up some distant memories, and I was able to dig up a little information on this proposal.
The puzzle is a "walking" tractor by Meredith W. Thring from 1982/'83. It was proposed (I doubt that it was ever built) as a possible replacement for draft animals (oxen, etc.) in underdeveloped countries. This proposal has two "legs' and two wheels, but a four "legged" version was also proposed.
