This is the tentative design for the legs for the Spider Tank i am developing. I may make some cosmetic changes between now and when the whole model is finished, but the methods of articulation used by this leg will probably stay the same.
The leg has three segments, two upper and one lower. It can walk upright in this configuration.
A look at the underside of the leg reveals the four points of articulation. The upper leg is split into two parts that can rotate independently of eachother. Then is the 'elbow' or 'knee' joint which allows the lower leg to rotate out from underneath the upper leg. Past the round black 2x2 brick buried inside the lower leg there is a mechanism to rotate that around its axis. Then finally, the wheel can be angled in for the tank to drive on it, or it can be pointed down like in the second picture so that the tank can walk on it.
This is the ideal driving configuration.
This pose shows the full range of motion and how the legs will allow the tank to walk over difficult terrain.
Here are more parts for two more legs. The bricks at front right show how I made the rotating core of the lower leg. I used a similar method for the core of the upper leg.
Having the legs rotate in this manner allows for a greater range of motion than the ball click joints, but does not sacrifice stability. There is more friction generated here than regular black technic friction pins could provide, so the tank will have enough stability and articulation for play and posing.
