Model of a Bessemer Hot Tube Oil Field Engine

[skyline1]

Keep leaning mate, I'm a great fan of cast iron bearings. Gus and I had a discussion about them a couple of weeks ago and they are more common than you might think. They are superb for high speed stuff. (Bronze can do some very strange things at high speeds) and they run silky smooth especially on Silver steel shafts (Drill Rod).

Regards Mark

 

[cfellows]

Keep leaning mate, I'm a great fan of cast iron bearings. Gus and I had a discussion about them a couple of weeks ago and they are more common than you might think. They are superb for high speed stuff. (Bronze can do some very strange things at high speeds) and they run silky smooth especially on Silver steel shafts (Drill Rod).

Regards Mark

Thanks, Mark. My sense is that cast iron bearings would be more forgiving if I fail to oil them as often as I should. I'm hoping this will be a slow running engine and the cast iron should wear pretty well.

Chuck

 

[cfellows]

Got a few more hours into day and made the crankshaft bearings.
The bearings are still a little tight, but they will loosen up with a little running in. Also, I'm beginning to wonder if that flywheel isn't a little too big???

Chuck

 

[kf2qd]

Actually - water jacket of some sort on the head would be more effective as the head takes most of the heat from compression and ignition. Similar to RC Nitro boats. A cooling coil around the head and they don't worry about the cylinder.

 

[skyline1]

Hi Chuck

I see you went for Cast Iron. I expect you had black hands machining them. That's the free graphite in the iron. It makes them at least partially self lubricating and they do have a long life. I have used C.I. in turbines and they can outlive ball races even thundering round at 30,000 R.P.M. or more.

Cast Iron is also good for the big ends in wobblers they get a hard life because of the side thrust on the conrod. Bronze tends to go oval fairly quickly.

Don't worry about them being a little tight they always are when new (or they should be) cast iron glazes in and forms a tough surface layer. I was told by an engineer from McLaren that it actually changes metallurgically in doing so and they were experimenting with it in full size racing engines. But I'm not a metallurgist so I couldn't guarantee that. Whatever the actual Physics and Metallurgy Cast Iron does make a great bearing material.

I am amazed at how fast this engine is coming together keep up the good work.

Regards Mark

 

[cfellows]

Actually - water jacket of some sort on the head would be more effective as the head takes most of the heat from compression and ignition. Similar to RC Nitro boats. A cooling coil around the head and they don't worry about the cylinder.

Hmm, interesting concept. I hadn't really thought about just cooling the head. I'll have to think about that...

Chuck

 

[cfellows]

Hi Chuck

I see you went for Cast Iron. I expect you had black hands machining them. That's the free graphite in the iron. It makes them at least partially self lubricating and they do have a long life. I have used C.I. in turbines and they can outlive ball races even thundering round at 30,000 R.P.M. or more.

Cast Iron is also good for the big ends in wobblers they get a hard life because of the side thrust on the conrod. Bronze tends to go oval fairly quickly.

Don't worry about them being a little tight they always are when new (or they should be) cast iron glazes in and forms a tough surface layer. I was told by an engineer from McLaren that it actually changes metallurgically in doing so and they were experimenting with it in full size racing engines. But I'm not a metallurgist so I couldn't guarantee that. Whatever the actual Physics and Metallurgy Cast Iron does make a great bearing material.

I am amazed at how fast this engine is coming together keep up the good work.

Regards Mark

Thanks, Mark. I've decided to stick with cast iron as much as possible. I've considered using aluminum for the piston to minimize vibration, but am thinking I can probably get and keep a better fit if I use cast iron. I don't want to use rings because of interference with the intake and exhaust ports, so a very close fit will be essential. I wanted to use o-rings, but would have to round over and polish the edges ot the ports to keep from shredding the o-rings.

Chuck

 

[Jasonb]

One of the problems with just water cooling the head on this engine unlike a Nitro Marine engine is that you won't get the force of the boat moving through the water to make the cooling water flow around the head, you really would need to add a pump a bit like the IHC vertical screen cooled that I made.

Also a water jacket will be better suited to the thermal movement that these type of engines rely on to make the water flow plus there is the fact its very slow reving and not encased in a hull like a glow engine so won't run anywhere near as hot.

J

 

[skyline1]

Hi Chuck

As you say aluminium would be lighter and as there is less mass being hurled up and down the cylinder every stroke it would tend to reduce vibration.

But to maintain good compression without rings to take up the slack as it were you would need a very close fitting piston. I think the problem would be that the thermal expansion of aluminium is much higher than that of the cylinder and could cause trouble as the engine got hotter at these close tolerances.

Cast Iron has an expansion closer to that of the cylinder so will be less trouble in this respect but it is heavier, a hollow piston could help something like an automobile piston perhaps.

Even if you don't use rings you could put oil retaining grooves on the piston.

Regards Mark

 

[Goldflash]

Hi Chuck. This type of 2 stroke design fascinates me and I have been doing some preliminary sketches of something similar that I want to make but using a stepped piston to increase the volumetric efficiency. My main problem is that I see that for the pump side of the Piston / Cylinder I need to use some form of automatic valves for both the Inlet and outlet. I am looking at either spring loaded poppet valves or reed valves. What sort of valves are you intending to use.
Another allternative maybe to have slide or piston valves operated by eccentrics .
Regards Ralph

 

[cfellows]

Hi Chuck. This type of 2 stroke design fascinates me and I have been doing some preliminary sketches of something similar that I want to make but using a stepped piston to increase the volumetric efficiency. My main problem is that I see that for the pump side of the Piston / Cylinder I need to use some form of automatic valves for both the Inlet and outlet. I am looking at either spring loaded poppet valves or reed valves. What sort of valves are you intending to use.
Another allternative maybe to have slide or piston valves operated by eccentrics .
Regards Ralph

I'm currently planning to use spring loaded ball check valves.

Chuck

 

[Brian Rupnow]

Chuck---Can you please direct me to a link that describes the operation of this engine. I did a bit of a search and found that "Half breed" conversions were popular for converting steam engines to run on natural gas, and that hot tubes were more reliable than the (at that time) young sparkplug and battery technology. I learned about "barkers" being installed on the exhaust so that an oilman could tell by the distinctive sound of each engine if all the engines in an oilfield were running. However, I didn't find much about the actual operating theory of the engines. I have never seen an engine like that, and would like to know more about them.----Brian

 

[cfellows]

Chuck---Can you please direct me to a link that describes the operation of this engine. I did a bit of a search and found that "Half breed" conversions were popular for converting steam engines to run on natural gas, and that hot tubes were more reliable than the (at that time) young sparkplug and battery technology. I learned about "barkers" being installed on the exhaust so that an oilman could tell by the distinctive sound of each engine if all the engines in an oilfield were running. However, I didn't find much about the actual operating theory of the engines. I have never seen an engine like that, and would like to know more about them.----Brian

A halfbreed engine is basically just a 2-stroke gasoline engine. Have a look at Jan Ridders page for a pretty good explanation, on a smaller scale.

http://heetgasmodelbouw.ridders.nu/Webpaginas/pagina_tweetakt_motor/tweetakt_frameset.htm

Old steam engines lent themselves to this conversion because both sides of the piston were sealed. The closed off part behind the piston acts like the sealed crankcase on a normal 2-stroke engine. A transfer port connects the back half of the cylinder to the front half and allows the fuel mixture to be transfered into the combustion chamber.

I assume you already know what a hot tube is?

Chuck

 

[Goldflash]

Hi Chuck I would be really interested in seeing how your Spring Loaded ball valves work
Ralph

 

[Brian Rupnow]

Okay Chuck---I did know how a two stroke worked. I have a "motor anthology" from 1913 that explains the hot tube quite well. i will have to read up on that. From what I remember (its been 30 years since I last read the book) there was a seperate reservoir of alcohol that one had to light first to heat up the hot tube before cranking the engine. I can't remember if the hot tube then gathered its heat from the engine exhaust or not. I'll have to go read the book tonight. All the two stroke engines i have known were high revving little monsters, but the videos I have watched of Bessemer type engines were quite slow.---Might have something to do with that "Out of proportion" flywheel.---Brian

 

[Brian Rupnow]

I went and read the book regarding "hot tube" ignitions. I had it partly right.---Sorta----The ignition tube was made of platinum, and sat where a sparkplug would normally go. Part of the tube was inside the cylinder head, and part protruded from the cylinder head. There was a small tank of Benzine right by the dashboard, that was a gravity feed to a bunsen burner like device (one for each cylinder). Each of these bunsen burner like devices had its own alcohol reservoir surrounding it. To start the car, you filled each burners alcohol cup and lit it on fire. This heated the burner to the point that any Benzene delivered to it would immediately vapourize. It was the flame from the vapourized Benzene that heated the platinum hot tube hot enough to cause ignition of fuel in the cylinders as you cranked the engine.

 

[cfellows]

Here's a link to some good info on operation of a hot tube.

http://www.old-engine.com/maghtu.htm

The hot tube does need to be heated by an external source before starting the engine. Once the engine is started, the fuel mixture is pushed up into the hot tube by the compression stroke where it ignites, also igniting the rest of the mixture in the cylinder. On many of the engines, the ignition of the mixture inside the hot tube was enough to keep it hot and the external heating source could be switched off.

Hot tube engines can be timed by making the hot tube longer or shorter or by moving the hot spot closer to or further away from the cylinder.

As far as running speed, I imagine and am hoping that the larger flywheel combined with a really long stroke will allow the engine to run much slower. And, of course, throttling and fuel mixture can also speed up or slow down the speed.

This whole 2-stroke thing is a bit of a new experience for me to, so I imagine I'll doing some experimenting once I get it running.

Chuck

 

[ShopShoe]

FWIW, I have seen early two-stroke IC engines described as "compound" gas engines.

--ShopShoe

 

[Brian Rupnow]

Chuck---Whats happening? Are you hung up on this project, taking a break, or posting elsewhere? I hope you are well and have no health issues. I am very interested in this build.---Brian

 

[cfellows]

Chuck---Whats happening? Are you hung up on this project, taking a break, or posting elsewhere? I hope you are well and have no health issues. I am very interested in this build.---Brian

Hi Brian,

Thanks for your concern. Right after we got back from vacation on Oct 1st, I came down with a nasty case of something resembling a bad cold and couldn't shake it. It's taken almost 6 weeks and two different rounds of antibiotics but I'm finally pretty much back to normal. Never was flat on my back, but just sick enough that all I felt like doing was sitting around in my pajamas and moaning a lot.

I cleaned my shop up a couple of days ago and as soon as I get caught up on the backlog of honeydo's I should be back in full swing on the Bessemer.

Thanks again...
Chuck