PKP class SM31

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SM31-044a locomotive.jpg
Type and origin
Power type Diesel-electric
Builder Poland Fablok
Model 411D
Build date 1976-1985
Total produced ca. 200
UIC class Co-Co
Gauge 1,435 mm (4 ft 8 12 in)
Bogies 2
Wheel diameter 1,100 mm
Length 17 m
Loco weight 116.4 t
Fuel type diesel
Prime mover a8C22W
Engine type four-stroke
Cylinders 8
Transmission electrical
Loco brake Oerlikon
Performance figures
Maximum speed 80 km/h
Power output 880 kW
Operators PKP
Class Poland SM31
Number in class 168
Nicknames Trumna
Delivered 1976

SM31 (production model 411D) is a Polish series of diesel shunting locomotives used by PKP and industry.[1]


SM31 class had been designed for shunting heavy freight trains in large freight stations, works and harbours. The design was elaborated in Fablok in 1973, mainly on the basis of SM42 locomotive. Production of this series lasted between 1976 and 1981, as well as between 1983 and 1985. In this period PKP bought 167 items of this series machines.[2] A total number of ca. 200 locomotives was produced, with the rest of them servicing Polish industry, chiefly mining.[3] Also first two prototypes (SM31-001 and SM31-002) were sold to industrial works, and the last one locomotive for PKP was re-bought from the industry (SM31-170).[2]

As the main purpose of this series was shunting heavy freight trains, after its introduction PKP possessed shunters suited for all purposes. For extremely light trains mainly SM03 locomotives were used. Medium light trains were shunted by SM30 series, medium weight trains were left for SM42 engines. The last thing to be done was the introduction of heavy shunter able to work in severe climatic conditions, what did not happen before SM48 were brought to Poland.[1]

Today SM31 locomotives are mainly to be found on Upper Silesia railway tracks, pulling heavy freight trains from works to marshalling yards in Łazy, Jaworzno, Szczakowa, Tarnowskie Góry and Rybnik. Other engines are deployed at the stations of Łódź, Nowy Sącz, Poznań, Szczecin and Wrocław.[2]

Technical data[edit]

SM31 is a Co-Co locomotive, what means it runs on two bogies, each equipped with three axles. Bogies are similar in construction to those used in SU45 and SU46 locomotives. This gives SM31 locomotive good performance on highland tracks.[2] Being a typical shunter, SM31 has one crew compartment of the same height as machine and electric compartments.[1] The engine (V8 compression-ignition engine) is in fact a developed version of SM42 locomotive engine, with its total power raised by ca. 50%. The engine propels main alternator, which gives power to six 196 kW traction motors.[1]


Trumna (En.: Coffin) - from locomotive's angular shape.[3]


  1. ^ a b c d Jarek D. Stwarz (1997–2002). "Chester Home Page". Archived from the original on 2007-08-31. Retrieved 2007-09-03. 
  2. ^ a b c d "Regionalny Portal Kolejowy". 2006–2007. Retrieved 2007-09-04. 
  3. ^ a b Przemysław Gołembiecki, Tomasz Gacki (2003). "Serwis Kolejowy". Archived from the original on 2008-01-05. Retrieved 2007-09-04.