Hydrocompressor tower

The most prominent feature of the Knesebeck installations is the 47 m high hydrocompressor tower. This mining monument was constructed in 1912 and was part of a water engineering system with which compressed air was produced for the machines in the mine for many decades.

With the hydrocompressor built at the Knesebeck Shaft in 1912/13, the Mining Museum in Bad Grund has what is probably the only surviving installation of this type. The compressor was in operation until 1977 and had a compressed air capacity of 660 m³/h.

When it was constructed, an additional 45 m tower had to be built in order to achieve an optimal height difference of over 100 m. The construction of such a tower was only necessary at Knesebeck Shaft because it is located on the side of a hill and the water is supplied from a basin on the hill, making it necessary for the water to reach a point 40 m vertically above the shaft. This was only possible using an additional closed pipe mounted on a steel framework tower. The water was thus transported by gravity to the top of the hydrotower, from where it plunged vertically into the depths.

Method of function and technology of the hydrocompressor tower

The hydrocompressor works on the principle of a closed pipe. The production of compressed air takes place through water pressure (hydraulic). The water pressure is used directly, without any further power transfer, to compress the air. A hydrocompressor consists of a water-filled downpipe, a riser pipe and a pressure tank functioning as the air separator at the deepest point of the pipe system. The downpipe is equipped with an open suction head for the intake of air. The falling of the water creates a lower pressure in the pipe, causing air to be sucked in and dragged down with the water. The permanent downward flow of the air/water mixture prevents the air from rising in the downpipe. The deepest point of the system contains the air separator. Here, the air separates again from the water but cannot escape and is therefore immediately available as compressed air. The height difference between the suction head and the outlet of the riser pipe dictates the usable water gradient.


The pressure of the compressed air is determined by the height of the column of water in the riser pipe.