Model of a Pair of Hydraulic Forge Bellows

Model of a hydraulic bellows on a baseboard. It consists of a barrel suspended horizontally in two forks and can be rotated back and forth through a quarter circle around its axis by means of a lever. The space inside is formed by a tube in the axis direction into an endless circle, which is then closed by a partition placed longitudinally between the outer and inner wall above the tube. On one side, on both sides of this partition, an inlet valve with a leather flap is attached; on the other side, outlet valves to which a ventilation pipe is connected. If the barrel is now half-filled with water, the space remaining for air is divided into two compartments: by rotating the barrel back and forth, these become alternately larger and smaller, because the water surface remains horizontal. Thus the airflow is created. The ventilation pipe is bent so that the end is level with the axis of rotation and connects to a fixed pipe in a wall behind the bellows.