The Colossus of Leonardo da Vinci

A multi-furnace foundry

The weights and masses to be moved inside the foundry were so great that, considering the iron reinforcements and the earth required for the horse casting mould, it would have reached around fifty tonnes. For this reason Leonardo developed special machines to move the sections of the mould.

The machine shown here would have lifted the entire casting mould. This detail makes us think that Leonardo initially intended to assemble the mould out of the casting pit; this idea was subsequently abandoned due to the mould’s excessive weight. Worried about the exceptional weight to be lifted, Leonardo drafted a system on the upper part of the beam that leads us to believe that he intended to reinforce the structure using a roof truss.

The turnover system was made up of a double rope winch and two pulleys. A screw system would make it possible to maintain the inside system’s centre of gravity and prevent it from turning over. The machine would move transversally thanks to the work of a winch.

This study illustrated the opening sequence of the furnaces according to the scheme for filling the casting mould. For this purpose Leonardo developed a pyrotechnic sensor in order to check the level of the bronze in the mould during pouring. Made up of gunpowder and placed at specific levels in the casting mould, the sensors would have lit up when the bronze passed providing a signal on the outside to open the next furnace.