ALTENBURGER rear derailleur
This is the first generation of the ALTENBURGER with the horizontal parallelogram from 1950.
For quite a long time two different designs of rear derailleurs competed to win the favor of the customers. The two different schools of thinking dominated the time the horizontal and the vertical parallelogram . The horizontal parallelogram by default delivered the higher number of teeth engaged. The enlacement was the dominating subject and the riders and mechanics belonged to the one or other school of thinking.
Today we know that both were wrong. Both designs had the disadvantage that the upper pulley was to far away from the cog and in case of the horizontal parallelogram it was for engineers obvious that only 1 and a half to 2 and a quarter of teeth are really distributing the chain tension and the other engaged teeth of the cog are only guiding the chain.
The first generation is completely made of sheet metal (steel) compared to the second made of die casted aluminum.