Ehrenfriedersdorf Whaterweel Pump

To better manage the troublesome and dangerous underground water, work began in 1536 on driving the "Tiefer Sauberger Stollen" (Deep Sauberg Adit), intended to create a natural drainage outlet. The Alexander-Tagesschacht (Alexander Day Shaft) — also known as the Heinzenschacht — was begun in 1542 and served as the eighth ventilation and access shaft for this adit. It connects to the level of the "Tiefer Sauberger Stollen" and extends deeper underground along the intersection of two richly mineralized veins: the "Alexander Spat" (copper ore) and the "Rothirschner Stehender" (silver ore).

Only with the connection of the "Tiefer Sauberger Stollen" — and the consequent successful drainage of water — in 1550 was it possible to control the water at depth and thus advance further into the depths of the Sauberg. For this purpose, a "Wasserkunst" (water-powered pumping system) was constructed, consisting of a wheel chamber with a drive wheel located just above the level of the "Tiefer Sauberger Stollen" and the actual water pump situated in the shaft extending below.

In 2000, during stabilization work on the Alexander-Tagesschacht, a filled-in cavity was discovered; once cleared, it proved to be the aforementioned wheel chamber. Further clearing work in the shaft below brought to light fragments of wood, metal, and leather — presumably remnants of the wheel pump installed in the 16th century. Dendrochronological dating of the wooden finds indicated that the timber had been felled in 1563.

This pumping system — also known as the "Ehrenfriedersdorf waterwheel pump" — was likely invented by local mining engineers around 1540; it was described and illustrated in the textbook De re metallica, published in 1556 by the Saxon polymath Georgius Agricola.

Historians regard the invention of the wheel pump as "the most important contribution of Ore Mountain mining to technological development in the late Middle Ages." This observation relates essentially to the arrangement of the pump sets and the invention of the crank for converting the rotary motion of the wheel into the up-and-down movement of the pump pistons. This principle of a water-lifting wheel pump remained the dominant method in mining worldwide well into the 19th century.

The water-wheel chamber, rediscovered in 2000 by staff from the visitor mine, measured up to 4.5 meters in diameter and up to 1.2 meters in width. During 2001, the shaft extending beneath it was further cleared and restored to a depth of 15 meters.

During the initial excavation work, a wooden pipe was uncovered lying outside the eastern bearing of the original water-wheel axle; this had evidently served as the piston pipe for the uppermost pump assembly. While this pump assembly was successfully recovered in its entirety, only the 2.0-meter-long suction pipe remained of the pump assembly located below it.

In 2006, the Ehrenfriedersdorf town council decided to install a replica water wheel, with funding provided by the town and the Free State of Saxony. In 2007, this reconstructed water wheel — built to the original dimensions — was installed in the historic chamber; to this day, it offers visitors to the tin mine a fully functional replica of the most important technical invention to emerge from Ehrenfriedersdorf for Saxony and the wider world.

The significance of this invention is likely far greater than previously assumed: during the reconstruction of the system, the discovery of existing platform sockets revealed that the shaft linkage was not attached directly to the crank; instead, a movable connecting rod — or "Pleuel" — was interposed between them. Without this groundbreaking invention of the crank and connecting rod, the steam engine, compressor, and piston engine would likely not exist today.

With this faithful replica of the "Ehrenfriedersdorf waterwheel pump," the Ehrenfriedersdorf visitor mine boasts an additional attraction that impressively illustrates the importance of the Ore Mountains' mining industry as a foundation for the industrialization of Saxony.