Model of a Ladder

Model of a two-part ladder. The extendable part has a wheel at the top of each leg and is extended with a crank and windlass at the bottom of the part: the rope runs over a pulley in one of the upper rungs of the part to the lower rung of the extendable part. Two stops prevent it from sliding back. The extendable part is also equipped with a stay, which automatically drops out at a certain height as a support and as a prop. The stay is incomplete.