[jvriezen]

Since the thread is revived, a clarification on the answer to the original question... As Inspector at 10K Lakes, I worked with a team that built a bridge tipper very simply. It was simply a standard wedge arm on a pivot, that was held just past vertical by gravity. A little movement of the robot, and it fell forward. A gate latch kept it down once it fell. No motor, no pneumatics, just the simplest of simple machines.

I never actually saw it in action, but I heard it worked marvelously well. I hope no one ran into it though....