Single Cylinder Opposed 2 Piston Engine

Rdean33422 · Aug 1, 2024

I was surfing the internet and this drawing showed up and cough my eye.

Gobron_engine_(Autocar_Handbook,_Ninth_edition).jpg

It is a 1900 Gobron-Brillié opposed-piston engine.
It is a 2 cycle 2 cylinder 4 piston opposed engine.
I have only been able to find 4 drawings of the engine and almost no technical data so a picture is worth...
I will try to build a single cylinder 2 piston 4 cycle opposed piston engine of similar design.
I have already built a 2 crankshaft 2 piston opposed single cylinder chain drive engine that runs just fine. So I have high confidence.

I usually start by building the crankshaft of the model first and then make the engine block fit the crank. I had to order the ball bearings for the crankshaft and I wanted to get started so I drew this up for reference.

I marked out the lines on a previously sized block of aluminum.

Milling out the parts that don't look like an engine.

Milling the connecting rod relief sections.

And the results so far.

Thanks for looking
Ray

Rdean33422 · Aug 2, 2024

Update
I milled the center hole and the side slots for the upper connecting rods.

This is where I usually paint the engine block some color but it looked so nice that I decided to just give it a good buffing.

Thanks for looking
Ray

Roger B · Aug 3, 2024

I am slowly building an single cylinder opposed piston two stroke diesel with side pull rods for the top piston.

I have question about your plans to make a single cylinder version of the Gobron-Brillié. As I see it the two pistons stop the top yoke from twisting, if you only have one piston it may tend to twist. This may not be a problem but I thought I would raise it. On the engine I am building the top yoke is guided by a square scavenge piston.

Rdean33422 · Aug 3, 2024

Roger you are correct and I haven't worked out just how I will address that problem yet. I will be making my cylinder longer than the cross arm travel with a longer slot to capture the twisting and turning forces through out its travel. There will probably need to be guides of some kind on each side of the cylinder also.

Rdean33422 · Aug 3, 2024

I had already milled the pieces for the crankshaft a few days back and was waiting for the ball bearings to come in. Well they got here late yesterday so today after mowing the grass I assembled the crank. The bearing pairs are visible in the two wider sections.

The two outer guide rods have been removed and after a couple of hours I will install the rod journals. Now the glue up will sit over night and then tomorrow the holes for the tapered pins will be drilled and pins installed.

Thanks for looking
Ray

Longboy · Aug 3, 2024

This is a big deal! A home effort on a design almost lost to the ages. These opposed twin piston cylinders are showing up again in contemporary talk and articles for automobile power by specific output, economy, weight and component part reduction. Haven't seen type as a model project before.......you bring something new to the forum! .Dave.

Rdean33422 · Aug 3, 2024

Dave thank you very much but I just can't stop building model engines especially ones that present a challenge.

Ray

kuhncw · Aug 3, 2024

The Kansas City Haypress engine has opposed pistons and linkage connecting the opposing piston to the crankshaft similar to your design.

Chuck

minh-thanh · Aug 3, 2024

Rdean33422 said:
I was surfing the internet and this drawing showed up and cough my eye.
View attachment 158639

It is a 1900 Gobron-Brillié opposed-piston engine.
It is a 2 cycle 2 cylinder 4 piston opposed engine.
I have only been able to find 4 drawings of the engine and almost no technical data so a picture is worth...
I will try to build a single cylinder 2 piston 4 cycle opposed piston engine of similar design.
I have already built a 2 crankshaft 2 piston opposed single cylinder chain drive engine that runs just fine. So I have high confidence.

I usually start by building the crankshaft of the model first and then make the engine block fit the crank. I had to order the ball bearings for the crankshaft and I wanted to get started so I drew this up for reference.
View attachment 158638

I marked out the lines on a previously sized block of aluminum.
View attachment 158640

Milling out the parts that don't look like an engine.
View attachment 158641

Milling the connecting rod relief sections.
View attachment 158642

And the results so far.
View attachment 158643

Thanks for looking
Ray

Interesting project

Please update ....

Rdean33422 · Aug 4, 2024

kuhncw said:
The Kansas City Haypress engine

Chuck I looked it up and found a wealth of information. Thank you

Drilled, reamed, and installed the tapered pins and gave it a paint job.
The paint isn't very dry but I had to see if the crank would fit the block.

It fits just fine.
Cut out 4 main bearing caps for tomorrow.

Thanks for looking
Ray

Lloyd-ss · Aug 5, 2024

Ray, I searched the USPTO and WIPO sites for any patent refs and didn't find any for that engine type in that era, although I found plenty of patents with Gustav Gobron as the inventor. He was a very busy guy!
Lloyd

Rdean33422 · Aug 5, 2024

He definitely was and after the partners split up he built the first automobile to break 100 miles per hour.

I got the main bearing caps installed and numbered so I won't get them mixed up.

Over to the lathe with a drill bit first to get a large enough hole for the boring bar. My stack up looks precarious but it did work.

Line boring to just under the size of the bearings. I will finish with an adjustable reamer on the bench.

Thanks for looking
Ray

Lloyd-ss · Aug 5, 2024

Ray, Is that line boring bar just a steel rod with a cross-hole for a hand-ground bit? And a center in the tailstock to stabilize the long end of the bar? how do you keep the vibration out of it?
Thanks very much, Lloyd.

Rdean33422 · Aug 5, 2024

That's exactly what it is and it doesn't work too well as it is only 1/2" rod. That's why I finish them by hand later but it does get close.

Ray

Rdean33422 · Aug 6, 2024

After some time reaming and adjusting it all worked out just fine. The crank does spin freely and fits in the block with about 0.005 wobble at the outer crank ends. That should be just fine.

Connecting rod, lower piston and wrist pin.

Assembled on the crank.

Thanks for looking
Ray

Lloyd-ss · Aug 6, 2024

Rdean33422 said:
That's exactly what it is and it doesn't work too well as it is only 1/2" rod. That's why I finish them by hand later but it does get close.

Ray

...............I wrote this yesterday and forgot to post it, so it might seem out of sequence..............
OK, I am a little relieved. The magic bullet is a secondary finishing operation, not some super stiff solid carbide rod with an integral boring and reamer, or some other secret mo-jo.

Roger B · Aug 7, 2024

Nicely done

I am interested in your use of ball races for the main bearings in a built up crankshaft but conventional split bearings for the big ends.

Rdean33422 · Aug 7, 2024

I would like to use ball bearings on all the crank positions but because of the way I make my cranks that isn't possible.
I think this may answer some of your questions.
https://www.homemodelenginemachinist.com/threads/6-cylinder-crankshaft.36148/

Ray

Rdean33422 · Aug 7, 2024

I started out with a 3" diameter aluminum bar and cut it down to 2.500 overall. Then I cut the center section down to 2" and bored the center out to 1.25 for the cast iron liner.
I have a garbage can full of aluminum strings.

3/4" boring bar with a 7" stick out.

Thanks for looking
Ray

Rdean33422 · Aug 8, 2024

I milled some index flats and drilled for the cylinder bolts.

It even fit first time.

I think that this engine is going to be rather tall.

Thanks for looking
Ray

Single Cylinder Opposed 2 Piston Engine

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