Rawoilmotors, or crude oil engines, or as we call them hot bulb engines. So called because they would run on crude oil or just about any other combustible liquid and because ignition involved a hot bulb, a sort of pre combustion chamber. When I say anything, I mean just about anything. Diesel? Paraffin? Used engine oil? Fish oil, if you used the engine to run a trawler? Creosote? Palm oil, if you had palm trees? They were all good.
Hot bulb engines would always start once you got the bulb hot enough and would keep running almost forever so they were popular in cold climates and remote places, which is why on my hols in Stockholm I found myself by chance in an industrial museum dedicated to the Pythagoras engine works which made them for much of the 20th century. It closed in 1979 and remained like one huge potential barn find until a group of enthusiasts persuaded the local town council to make it into a museum.
They made their engines (and other products) entirely by hand with craftsmen machining parts like this crankshaft
and this piston and rod from cast iron blanks on a lathe
The business never became big enough to be able to invest and compete with more automated rivals and so it disappeared together with several dozen other makers throughout Sweden.
The museum’s other claim to fame is this running but not over restored Ford Thames Trader which they take around to classic and vintage shows. Interestingly it’s LHD despite being made well before Dagen H.
So there you have it. Well worth a visit for the mechanically inclined who find themselves in Norrtälje.