I was just watching Robocop the other day when I noticed sort of a design flaw / cheat on the stop motion puppet.
(Robbins I borrowed one of your fantastic renders you should really do more of BTW, is it rigged to move?)
The hydraulic rams that articulate the reverse knee aren't connected to the rest of the leg. They sit on that Yoke (Point B) and you'd think that's the actual turning point of the knee.
If you look at Point A on the diagram. This is the actual point where the 'knee' rotates. You can see it clearly in the scene where Ed209 is on his back having his tantrum after falling down the stairs and robo walks away from him.
The rams are sort of for show in a design sense, as they don't really push the knee up and down (that is to say they aren't connect to any bearings to push the knee through its motion apart from the bearings of the yoke they connect to, they just sort of...rest there.) They do move but independently of the knee e.g. You can keep the knee perfectly still at a 45 degree angle and still have the rams move the yoke.
There is also a thin pillar in between the rams which is fixed all the way down, this would have to be pivoted on the bottom too and it's not it's flush with the circular plate.
You can also see the large vertical gap in the back of the tram that raises the knee along the rails (Point C). It is this size so that when this true point of rotation moves the screw is not caught in the way.
View attachment 283080
Not sure why they did this unless it was an engineering issue, maybe the fake knee couldn't support the weight as right under that you have that circular plate which articulates the leg on the X-Axis.
You could say that the ram driven yoke isn't attached with bearings to the knee itself and rather pushes freely at the knee but this would involve some serious friction and wouldn't be very efficient.
Just a thought... Went off on one this evening.