Schwimmtor

The Schwimmtor (Floating gate), also known as the Sperrschiff (Blocking ship), was a floating barrier designed to protect the areas along the Donaukanal in Vienna from flooding and ice. It was built by Wilhelm von Engerth, entered service on 13 December 1873, and was scrapped following World War II.

The Schwimmtor was located 166 metres downstream of the Brigittenauer Spitz. The site was chosen because the canal was thin enough at this point that the floating barrier could withstand the pressure which would be caused by an accumulation of floodwater or ice.

A rounded indentation was carved into the left-hand (Brigittenau) quay wall, where the Schwimmtor was to be stowed when it was not needed. Just downstream of this indentation, the quay wall jutted out into the middle of the canal, thereby forming a support against which the barrier could be placed when it was needed.

Supporting the barrier with the same sort of elongated wall on the right-hand (Nussdorf) bank, thus creating a sluice-like gate, would not have been possible, because the current would have made it impossible to remove the barrier again once it had been placed across the canal. For this reason, a niche was carved into this quay wall. The niche was capped and housed two moveable steel barriers (the Stemmtor and the Anlagetor).

These moveable steel barriers could be brought into position by turning a capstan located above the niche. This was connected to the barriers by a rack and pinion, which turned the Stemmtor outward and moved the Anlagetor out of the niche in the wall to form the second support for the floating barrier.

Both the Stemmtor and the Anlagetor were steel truss constructions designed to absorb pressure placed on the floating barrier and to transfer these to the quay wall, to which the Stemmtor was attached.

In order to open the Schwimmtor, the moveable steel barriers were wound back into the niche in the wall using the capstan. The current in the canal would then naturally push the floating barrier back to the Brigittenau quay.

The Schwimmtor could be made to sit lower in the water if loaded with ballast. However, in order to prevent it from blocking the bottom of the canal, four struts made of cast iron and filled with concrete were produced. These ensured that an opening 95 centimetres tall was kept free. The small size of this opening resulted in a very rapid passage of water with great destructive force. The struts were therefore placed on a concrete plate 126 centimetres thick and 30 metres long.

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Wikipedia