In 1905, Krauss and Maffei each had a type of four-coupled local railway locomotive developed, which was intended to enable economical operation, especially with light passenger trains, and should be operable by just one person. The PtL 2/2 was designed by Maffei and was able to assert itself against the ML 2/2 from Krauss.
The basic idea behind the design of the locomotive was a spacious, centrally located driver's cab and the use of a semi-automatic dumping device to load the grate with coal. The boiler and attachments were arranged in such a way that the driver could leave the driver's cab on both sides and reach the wagon train directly via a running board. In addition, despite the small dimensions of the locomotives, a smoke tube superheater was already used in order to take advantage of the still young superheated steam technology. The boiler was almost entirely inside the driver's cab, only the smokebox and chimney sticking out at the front, and at the back one could see the end of the firebox and the coal bunker with the built-in chute. The very generous dimensions of the driver's cab and the large windows earned them the nickname “Glaskasterl” or “Glas-Chaise” in Franconia, whick both stands for “glass box”.
Three batches were produced, which differed mainly in terms of the engine. The first six machines from 1905 and 1906 had the cylinders inside the frame, which proved to be too maintenance-intensive. Therefore, these vehicles were already retired in 1923.
Original variant
Die Lokomotive, September 1906
From the second batch, the cylinders were on the outside, which significantly simplified maintenance. In addition, space was now free within the frame for the water tanks, which had previously been located above the frame next to the boiler. As a side effect of this changeover, there was now more space on the running boards. In order to be able to do without long connecting rods despite the long wheelbase, the power was first transmitted to a jackshaft between the axles. A total of 29 vehicles of this variant were built in 1908 and 1909.
The last batch consisted of nine and four locomotives, which were delivered in 1911 and 1914. With these, the wheelbase was shortened by 50 cm, which meant that the jackshaft could now be dispensed with. Instead, the drive was on the second axle. The total length was also reduced by about 20 cm.
The Reichsbahn took over nine examples of the second batch and all 13 of the third batch. They were classified as class 983 and given the numbers 98 301 to 98 322. In the period leading up to the end of the Second World War, some machines were sold to private railways and one to Austria. The latter was used by ÖBB as road number 688.01 until 1959. On behalf of a Lower Saxony light railway, a locomotive was provided with conventional layout until 1950, i.e. with a driver's cab at the end of the boiler. The fittings were moved to the back of the firebox and the switch to manual grate loading took place. The remaining machines came to the Bundesbahn after the war and were mostly retired in the fifties, but the last survived until 1963. Today there are still two PtL 2/2, but they are no longer operational. One of them is in the steam locomotive museum in Neuenmarkt-Wirsberg and the other is in the DB Museum in Koblenz as a functional cross-section with the boiler cut open in the middle.