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Area of application

This engine type was used as a stationary power source for driving pumps, generators, wiches and so on, and as a mobile power source in boats and the BM 10 tractor.


The Type W3 hot bulb engine was introduced in 1924 and remained in production until 1952. In its marine version, it was designated W3 M 2 and when fitted to the BM 10 tractor (1946-1952) it was known as the W3 T 202. For fast boats, 2 x W3 engines were fitted to boost power. 

Although the engine's basic configuration remained unchanged throughout its production lifetime, it was nevertheless continuously developed over the years and many improvements were introduced. As a tractor engine, for instance, it featured an electric starter and the bulb was heated via electric heating coils. The power output was also increased and when the tractor was tested by the Statens Maskinprovningar (Swedish Machinery Testing Institute) in Ultuna, the engine produced 23.1 hp at the beltdrive.

The engine shown at the museum was built in 1929. The engine's original installation is unknown, but according to surviving documentation it was bench tested in a brake rig by Bolinder-Munktell in 1937 after a repair. There is a note from as late as 1957 veryfying that the engine was adapted to power a generator. 

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Hot bulb engine W3 S 202


 Engine                                              2-cylinder, 2-stroke hot bulb engine

Engine output                                  15-20 hp vid 1 000 r/min

Cylinder bore/stroke                      120/120 mm

Cylinder volume                              2,72 dm³

Turnwheel diameter                       550 mm

Governor type                                 Centrifugal

Starter system                                 Compressed air 10 kp/cm³

Serial number                                  20807-08