The Class P 4 steam locomotives of the Palatine Railways were

express train An express train is a type of passenger train that makes a small number of stops between its origin and destination stations, usually major destinations, allowing faster service than local trains that stop at most or all of the stations alo ...

locomotives with a 2'B1' (

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

) axle arrangement and a four-cylinder

compound engine A compound engine is an engine that has more than one stage for recovering energy from the same working fluid, with the exhaust from the first stage passing through the second stage, and in some cases then on to another subsequent stage or even st ...

. A total of eleven locomotives were built by Maffei, numbers 286–291 in 1905 and 302–305 and 433 in 1906. They replaced the P 3.1 in express train service. The locomotives were initially fitted with Pielock superheaters, but after a few years they had to be removed again due to corrosion damage. From then on the locomotives operated as wet steam engines. The P 4 was one of the first locomotives in Germany with

bar frame A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure o ...

s. It was based on the Bavarian class built in 1903, the S 2/5; up to the second coupling axle, both types were almost the same apart from details and minor dimensional deviations. However, the P 4 had - unlike the S 2/5 - a wide

firebox Firebox may refer to: *Firebox (steam engine), the area where the fuel is burned in a steam engine *Firebox (architecture), the part of a fireplace where fuel is combusted *Firebox Records Firebox Records was a Finnish record label based in S ...

which was arranged completely behind the coupling wheels. For this reason, the distance between the coupling axle and the rear carrying axle had to be increased significantly and the carrying axle had to be designed to be radially adjustable. This and also the streamlined cab of the P 4 gave the locomotives a distinct appearance at the rear. The P 4 was also closely related to other Bavarian locomotive types from Maffei: the engine was adopted almost unchanged for the high-speed locomotive of the S 2/6 built in 1906 - only the cylinder diameters were slightly enlarged - otherwise both locomotives had a lot in common. The family resemblance to the Class S 3/6 built from 1908 onwards is also unmistakable; the latter looks like an enlarged P 4 with a coupling axle added. In the provisional reclassification plan by the

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all eleven locomotives were due to be reassigned numbers 14 151 to 14 161, but they were decommissioned before the redesignation.

Literature

* Wilhelm Reuter: ''Die Schönsten der Schiene – Die Geschichte der Atlantic''. Transpress, Berlin 1993, ISBN 3-613-01512-9 {{Palatine locomotives P 4 Railway locomotives introduced in 1905 Maffei locomotives Standard gauge locomotives of Germany Passenger locomotives 4-4-2 locomotives