Tank with Arm

While being frustrated trying to build a smaller walker, I decided to have a break and build something different; something easier :)

The only remarkable thing of this construction (if anything) is maybe the claw, which has 3 independent degrees of freedom (it can rotate, open/close and tilt independently). Basically, I just wanted to build the claw, but once I was done, I just built it a body in the form of a tank just for fun. This is what came out:

As stated before, the only remarkable thing is the claw. These pictures show it in more detail:

The key point are the two frictionless 16 tooth gears, which allow for the axle that opens and closes the claw to go right through them. For allowing rotation of the hand without the claw opening or closing at the same time, the two axles connected to the two universal joints need to rotate at the same time. That is precisely what the two differentials achieve. When one motor is on, both axles rotate at the same time (for rotating the claw), and when the other motor is on, only one axle rotates (for opening and closing the claw). Here you can see a video of this in action:

Finally, a video of the while creation in action:

Now back to my walkers :)