I consider walkers any machine that exhibits the following,

- The entire weight of the machine is supported at all time (no hoppers)
- The legs are made of more than a single piece of metal, ie a leg like you have yourself made up of two separate sections
- The upwards and forwards motions come from two separate mechanisms

I don't like the mechanisms in scuttle as if you take off the legs, it could still in theory run along the ground on the gears