The reference for locomotives and railcars
Bavarian ML 2/2 and Hungarian State Railways series 12
German Reichsbahn class 9836
Germany | 1906 | 26 produced
Die Lokomotive, August 1906

The ML 2/2 was a local railway tank locomotive that was built by Maffei between 1906 and 1908 as an alternative to the more well-known PtL 2/2 by Krauss. Although it was a very small and light locomotive, it was fitted with a very complicated and difficult to maintain powerplant. The “M” in the designation goes back to the term “motor locomotive” and serves as a reference to the powerplant with opposed pistons. There was a cylinder on each side between the widely spaced axles, the counter-rotating pistons of which acted on both wheel sets with short connecting rods. Inside the frame were the coupling rods that connected the axles.

With this special arrangement, the prospect of a perfect load balancing was presented. The maximum car load at 50 km/h on the level was 65 tonnes. The same load could still be pulled on a gradient of 2.5 percent at around ten to twelve km/h.

Otherwise, the ML 2/2 was designed to be just as suitable for everyday use as other Bavarian local railway locomotives. In order to be able to do without a fireman, there was a dumping device for semi-automatic loading of the grate. Passenger cars could be entered from either side of the locomotive. On a towed train, the gangway consisted of a door at the rear of the cab. However, if the train was pushed, the transition could be reached via a running board on the sides of the boiler. For this purpose, the water tanks were narrow and elongated so that they could be walked past without any problems.

24 examples were built for the Bavarian State Railways, three of which were sold to the firebrick factory in Marktredwitz in 1922. The rest were retired in 1924 because the maintenance of the internal parts of the engine was too expensive. The planned transfer to the Reichsbahn numbers 98 361 to 98 384 therefore did not take place. In 1907, the Hungarian MÁV had two ML 2/2 built under license for suburban traffic in Budapest. In contrast to the Bavarian engines, they had an certified maximum speed of 60 km/h, since the complicated powerplant was expected to run smoother.

VariantML 2/2MÁV 12
Axle config0-4-0T (Four-coupled) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length21 ft 6 11/16 in
Wheelbase9 ft 6 3/16 in
Fixed wheelbase9 ft 6 3/16 in
Empty weight38,581 lbs
Service weight48,502 lbs
Adhesive weight48,502 lbs
Axle load24,251 lbs
Fuel capacitycoal
Power sourcesteam
Indicated power194 hp (145 kW)
Optimal speed27 mph
Top speed31 mph37 mph
Starting effort4,553 lbf
Power Plant
Driver diameter39 in
Boiler pressure174 psi
Expansion typesimple
Cylinderstwo, 10 7/16 x 11 in
Grate area8.9 sq ft
Evaporative heating area382.1 sq ft452.1 sq ft
Superheater area70 sq ft
Total heating area452.1 sq ft522 sq ft
Calculated Values
steam locomotive
secondary line
tank locomotive
last changed: 01/2022

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