On display at the German Steam Locomotive Museum at Neuenmarkt in Upper Franconia, i.e. Northern Bavaria, (www.dampflokmuseum.de) is a cut open cylinder, including the piston,
of a highly unusual type which is nowadays almost forgotten.
Research by the author revealed that the cylinder exhibited at the museum had been taken from a Bavarian E 1 class, 2-8-0 type freight steam locomotive, built in 1896. The engine in question
is a compound type engine with one high- and one low-pressure cylinder each on either side of the locomotive. The highly integrated high- and low-pressure pistons are machined out of a single
casting and configured in a tandem arrangement as are, naturally, the cylinders. This arrangement is called Sondermann-type. The paper describes the working of the engine, including
sketches.
Despite its advantages (lower weight, smaller heat losses), this very complex engine configuration required rather involved manufacturing and maintenance processes and was never put into
service. In the end, the four locomotives built were converted to feature more conventional engine configurations.
