The Movement Mechanism
Hero’s automaton was characterised by movement and animation: it travelled forwards of its own accord, brought Dionysus to life, then returned to its starting position. Remarkably, one simple mechanism powered movement: a falling weight attached to a rope wound around an axle.
As the rope unwound, it rotated the axle.
To slow the weight’s fall and extend the performance, the weight was placed at the top of a grain-filled column. As the grain flowed out the hole at the bottom of the column, the weight fell, like sand through an hourglass.
Hero described four different motions:
- Straight-line motion, tried and tested, and represented here, was achieved through one axle attached to two equal-sized wheels that propelled the automaton forwards and backwards
- Circular motion: differently sized wheels were used to move the automaton in a circle.
- Rectangular motion around corners, created by two sets of wheels at right angles, which engaged at different times. This was more experimental and was perhaps inspired by Assyrian and Hellenistic siege machines which reoriented their wheels to avoid obstacles.
- A winding, snake-like motion, achieved by giving each wheel its own,
independent axle.
For all four types of motion, a third, unpowered wheel provided directional control and stability.