The Class PtL 2/2 locomotives of the Royal Bavarian State Railways (Königlich Bayerische Staatseisenbahn) were light and very compact superheated steam locomotives for operation on Bavarian branch lines (known generally as Lokalbahnen).
Common to all the variants was the B axle arrangement (European or UIC classification) or 0-4-0 (Whyte notation), the semi-automatic, gravity-feed firing that enabled one-man operation, and platforms with guard rails, front and rear, that enabled safe access to the coaches.
Unlike the better-known later variants the water tank of this 'ancient glass box' (Ur-Glaskasten) was arranged over the gangway, but in such a way that crossing over to the coaches in the train was still possible.
In the Reichsbahn's provisional renumbering plan of 1923, all six locomotives were included as numbers 98 301 - 98 306; they were however taken out of service in the same year.
This driving gear enabled the water tank to be located below the boiler in the frame, so that there was more space on the gangways.
A second engine, numbered "4515", had been cut in cross-section to explain the internal workings of a steam locomotive.
It was an unfortunate victim of the great fire at the Nuremberg Shed in October 2005, but after a successful renovation is now displayed in the DB Museum, Koblenz.