Here is video of a Lanz Bulldog tractor with a Imbert Gasifier. http://www.youtube.com/watch?v=ST7eDSIdwWU
The engine is a single cylinder 2 stroke semi Diesel which relied on a hot bulb for ignition. To start the tractor this bulb needed to be heated with a blow lamp. For more detail see http://en.wikipedia.org/wiki/Lanz_Bulldog.
actually the hot bulb engine is a full diesel engine. The semi diesel engines in those tractors are the next generation and were built as of 1952 and were started with a mixture of gasoline and diesel fuel, using a permanent ignition system with a single spark plug (with multiple (2 or 3) spark ports though!). Once the engine was hot enough you would change to straight diesel fuel and continue. Not forget to switch back 2 or 3 minutes before shutdown, to get the mixture back in the system and to the injection nozzle for the next startup. I know what I’m talking about: My father, my brother, my uncle and myself, we have a couple of those semi diesel tractors and of the generation after that, which are back to full diesel (this time with glow plugs). Each new generation of those engines (and tractors) accomplished a remarkable improvement w.r.t. fuel efficiency. The woodgas version (like in the video you linked to) is always the oldest with the hot bulb engine.
My understanding of semi Diesel is as follows.
Semi-Diesel Meaning and Definition
- (a.) Designating an internal-combustion engine of a type resembling the Diesel engine in using as fuel heavy oil which is injected in a spray just before the end of the compression stroke and is fired without electrical ignition. The fuel is sprayed into an iron box (called a hot bulb or hot pot) opening into the combustion chamber, and heated for ignition by a blast-lamp until the engine is running, when it is, ordinarily, kept red hot by the heat of combustion.
you are totally correct! I had to do a little research in order to clarify this for myself:
The colloquial name for those tractors, as I mentioned, is semi diesel (“Halbdiesel” in German - was even the name on the brochures and stuff…those tractors were started with diesel-gasoline mixtures and spark plugs, as I explained).
But, scientifically, a diesel engine is defined as a compression-ignition engine, that ignites the fuel just due to the air in the cylinder being hot from the high compression (in German called self ignition). Therefore, the hot bulb engine is not a “real” diesel engine (acc. to this definition). It depends on the hot bulb, which can be considered an ignition starter or external ignition device. AIUI, that is where the semi-diesel or pseudo-diesel name comes from.