Sunday, November 16, 2014


I'll try to model the semaphore signals and turnouts in Emsingen and Talheim to be controlled mechanically following prototype practices. Wikipedia has some nice background information on Mechanische Stellwerke (in German). Note: The English version of this page strictly refers to U.K. technology, that is similar to the German prototype, but looks quite different.

The basic concept of mechanical signal towers is that each turnout and signal is moved with a lever in the signal tower that is connected to the turnout or signal with steel wire arranged in a loop.

The wire loop between signal tower and the signal or turnout needs to remain under tension for the system to function properly as it stretches and contracts over time, as well as with temperature fluctuations. That's where "Spannwerke" (wire tensioners) come in. Using a combination of pulleys a weighted arm pulls the wire taught. The main forms are "Signalspannwerke"to tension signal wire loops, and "Weichenspannwerke" for turnout wire loops. They differ in various aspects, but the most visible is that Weichenspannwerke are built more sturdy, and the weights are heavier. Spannwerke are a signature feature of this technology and very visible. Weichenspannwerke are often located inside the base of the signal tower, if there is room. Signalspanwerke are often located near the signals they serve, to ensure higher reliability in case of wire breakage.

The models in the photo are of different types and come from several manufacturers. The two Signalspannwerke on the left are from Auhagen (part number 12242). The two Signalspannwerke on the right and the five Weichenspannwerke on top are from Faller (part number 120141). Finally, the four Signalspannwerke in the lower middle are from Vollmer (number 5136).

The Signalspannwerke from Faller #120141 are quite nice. I added the guide rod by drilling a small hole in the arm and adding a piece of thick magnet wire. I may add the wire loop later. The Weichenspannwerke out of the box are quite awful and too bulky. I lessened the blow a bit by extending the base and adding the guide rod.

Auhagen's Signalspannwerke are nice and detailed. They guide rod is suggested, but doesn't stick out above the arm. That is easy to fix, but not done in the photo yet.

Vollmer's Signalspannwerke were a very nice surprise. They are finely molded and have all required parts including the guide rod and the wire loop around the pulleys. In fact, the quality of these models made me modify the others to bring them to a similar level of detail.

Of course, all models need to be painted to look reasonable.

"Mechanische Stellwerke, Band 1", Stefan Carstens, MIBA Report, ISBN 3-89610-211-7

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