Hot bulb/Hot tube

Further to a private display of ignorancishness by myself, can someone
explain the differences (in words of fewer syllables than rodomontade :-)
between Hot bulb ignition and Hot tube ignition.
Please try not to be pusillanimous in your castigations of my specific
gravity :-)!
Arthur G (intoxicated by the exuberance of the group's verbosity, oh and
Reply to
Arthur Griffin & Jeni Stanton
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Haven't got into anything alcoholic yet, but will no doubt find something suitable... :-))
As far as I understand it, hot bulbs are used on oil engines and hot tubes are used on petrol/paraffin engines, but there is probably a very thin dividing line betwixt the two things.
Hot-Bulb semi-diesel engines like Bolinders are quite explicit.
Hot tube ignition nearly always comes up when discussed with petrol/paraffin engines, which almost always end up being converted to magneto ignition to make them more reliable. Then we get them and restore them and convert them back again....
-- Peter & Rita Forbes Engine pages for preservation info:
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Reply to
Peter A Forbes
As I understand it the only difference is the physical appearance. Blackstones and Hornsby's are generally hot bulb (where you effectively heat the end of the combustion chamber until it is sufficiently hot to ignite the charge), whereas others like Tangyes had a hot tube which is a closed off tube protruding from the head which is heated to similar effect. Hot tube should (IMHO) be more efficient as there is less mass of metal to be heated, but more likelihood of the tube melting. The true all-encompassing description for all of them should be surface ignition (I think - shouldn't have finished the second bottle of Riesling!).
Reply to
Dan Howden
If Santa brings me a dictionary, perhaps I can do whatever it is you just said. I'll give my interpretation, at the risk of displaying my own ignoramitousnous.
A hot tube is closed off at one end like a test tube. As the fuel/air is compressed within the cylinder, some enters the hot tube, where it is ignited.
A hot bulb, on the other hand, is a chamber to preheat the fuel/air to a temperature more conducive to ignition.
=-=-=-=-=-=-=-=-= Rob Skinner La Habra, California
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Reply to
Rob Skinner
despite my inherent intoxication I must render the following explication: The hot bulb is a largeish mass, used in semi-diesels, of metal designed to impart to the cylinder the necessary heat to propagate to the incoming charge the essential "heat of combustion" that would, in a full diesel, be imparted merely by the compression of the air alone. The hot-tube is but a projection from this mass designed to exercise some rudimentary control over the ignition timing. ttfn Merlot mong
Reply to
Roland and Celia Craven
Morning all, and thanks guys. Damn, this aspirin really hits the spot!
Regards, Arthur G
Reply to
Arthur Griffin
Further to a private display of ignorancishness by myself, can someone
Put simply, there ain't none ........
Engineering textbooks dating from the turn of the century use the terms pretty much interchangeably. There are physical differences in their construction between different engines, & one can easily see why some are coloquially called bulb & some tube, but that seems to be expedience rather than engineering concepts talking.
I know that on a very cold day I put most heat on a different part of the tube on my Handyman, & that place also varies with the type of fuel I've got in the tank. That's the crude ignition timing that Roland refers to. Sometimes on a very cold day when I couldn't be bothered to change fuels for start-up or I can't remember what noxious mix I left in the tank, I'll put a big blowlamp onto the cyclinder head & convert the whole lump into a hot bulb!
Reply to
Colin Osborne

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