Hot Bulb and Glow Plug Difference

Hello again Roger,

Thanks for the information on injection timing and compression ratios.

I had not seen this dual pump and glow plug arrangement before. I have been to the Paderborn museum in Germany where they have a large collection and there are tractors with the Zundkerze and ignition coil but I don't think they have any with the dual pump/dual injector + Gluhkerze arrangement. I have seen the use of a glow plug mentioned in connection with the higher-compression halb diesel that came later.

I did have some correspondence some time ago with Andy Watson who runs the Lanz Bulldog register in the UK and he mentioned the pendulum type electric starter that seems to mimic the hand starting process. I assume they did this to reduce the size of motor (and battery) required compared with something that would take the engine all the way over compression - or maybe there was a more subtle reason?

The tractor near us has a rotating dial to indicate the engine direction. I have read stories of the engines spontaneously reversing when running at low speed so I can see the need for something of this kind (although you would probably realize fairly quickly if you started to go backwards!?)

Do you have any further comments on Bolinder engines or is the Lanz your main area of interest?

As an aside - what do you have to do to add pictures to a post, I have tried copying on to the clipboard then using Ctrl +V in the little window that comes up, but it just does not work for me. Is there something I am missing?

Thanks again and best wishes

John

John, to add pictures you first have to put them in an album via the icon on the green bar at the top of the page. You can then insert them in a post using the camera icon at the top of the posting box.

What I know of the Bolinder engines comes from the old engine website of which I am sure that you are aware. They also show an interesting load control system used on the Gardener hot bulb engine where the injector spray was asymetrical and the injector was rotated.

**LINK**

I would imagine that you would need an understanding of Swedish to get deep into the Bolinder history.

My interest is more in full diesels as I am currently building a 20cc horizontal 2 stroke diesel loosely based on the Field Marshall engine.

It has run as a spark ignition engine with a carburettor and low compression cylinder head so I know that the porting and crankcase compression are ok. The fuel injection system works as manifold injection on another petrol engine. I am now trying to get the whole system working together but so far having only achieved blue smoke from the exhaust

Best regards

Roger

I will just try putting in a couple of photographs to see that it works, This is the Bolinder B or W engine:

This is the earlier E type which used water injection:

And the M type with air injection (not sure how it fits in chronologically) the air compression is seen at the end.

Anyway many thanks for all the information you have supplied and good luck with your full diesel. I will try posting a response to the Norwegian gentleman who participates in the forum, to see if he knows any more about Bolinder.

John

In Norway are the bolinder hot bulb engine rare used, mostly norwegian produced hot bulb/semidiesel engines. We had imported some June-Munktell semidiesel. Then i can't answer at your question.

Here is the norwegian engines who are produced in Norway. http://semidiesel.no/Hjem/generell%20historie.html

Edited By Jens Eirik Skogstad on 21/05/2018 17:38:26

Thanks Jens Erik

I did not realize that there were so many manufacturers of hot bulb engines in Norway. I had heard of Dan, Grei, Rap and Wichmann, (I saw one of the latter in a visit to your country in 2008.) It seems that almost every significant port had someone making these engines.

We will be visiting again in July this year, are there any museums or collections that I should try to visit?

John

The paper SAE 2002-01-0115 describes test results for a lot of early engines from Sweden.

The latest glowhead engines reached 35% thermal efficiency.

Edited By Niels Abildgaard on 23/05/2018 05:34:05

Yes, it was about 120 difference brands of hot bulb engines produced in Norway, both from factory and black smith.

About engine museum in Norway, see this map.. **LINK**

Glowhead? We call it hot bulb who are correct in english..

Sorry not to have replied sooner, I have been busy with some other things the last couple of days. Concerning Niels mention of the SAE paper, I did download a copy of this and was quite surprised about how well the hot bulb engines compared with the diesel and spark ignition engines tested. The one doubt I have is that the author is clearly analyzing information from tests carried out by others and has drawn an arbitrary distinction between "hot bulb" and pre-chambered diesel engines (presumably with glow plug heaters for starting.) He works on the basis that an engine with a compression ratio of less than 13:1 is hot bulb and above this it is a diesel. Most people would regard a "hot bulb" engine with a compression ratio of more than 6 or 8:1 as a "semi diesel".

Regarding the terminology; in English "hot bulb" and "semi-diesel" are the words normally used. I know that in German they use the term "Gluhkopf" which means glowing head - similar to your own terminology.

Jens Erik - thanks for the information on museums.

John