Walking Doll Joints

Okay, beside the doll being nude....do you recognize the leg joints? I find this mechanism very intriguing. What makes it tick? Or walk? I should say.
My doll is from the fifties and its composition is hard plastic. Hard plastic maintains it's structure, color and shape, rough play is the only enemy. I can figure the walking joints are best installed in hard plastic.
The walking starts with the feet planted on the floor, tipping the doll slightly backwards creates a lifting of one leg. Children could play like this repeatedly for hours. Some walkers also have a mechanism that will move the head side to side while taking each step.
I haven't a clue how, nor have I ever seen the mechanising outside a doll's body. This side view is a little blurry but I thought it was a neat picture.
I wouldn't be able to retake it ever again. I've a nosey dog.

Here is a short snippet of the walking with me manually moving one leg.

I'll portray the doll at a later time. C&G Design.