Junkers CLM

[GRAUBELE]

Hello Roger

The Junkers engine is a very interesting project.
A member of my vintage tractor club has an original Junkers engine that drives a generator.
At operating speed, the engine makes a lot of noise...

Dieter

[Casting Iron]

Nice piece of equipment !

.

[Roger B]

I find these engines very fascinating and I once got a tip from a school friend years ago that there was still an engine like this in an old railway signal box. It was used there as an emergency generator. But it was only used for maintenance all these years.
My school friend works for the railway himself and got the OK from “above” so that we can remove the engine. The signal box will also soon be demolished and the engine will be scrapped.
The signal box was in the middle of busy tracks and we had to get the individual parts across the tracks as quickly as possible. The whole campaign wasn't really official either 🤫. But everything worked well. (Officially asking the Deutsche Bundesbahn wouldn't have worked, but there were still people on the railway who loved old technology.)
Now the thing is in the old pig sty and there has still been no power outage. The engine starts with one revolution of the hand crank. This is an advantage of the two pistons. The disadvantage: the engine is loud as hell.

Michael

<a href="https://www.youtube.com/watch?v=D82Y-s3200M" target="_blank">http://www.youtube.com/watch?v=D82Y-s3200M</a>

Michael S also has a Junkers generator set, it's just as loud 

[pirmin]

A firend of mine has two of these engines, one two cylinder and one single cylinder version. he got them from the Danube shipping doc yard in vienna for free, basically never have been run since they where as a emergency agregat sitting somewhere well stored, dry and maintained. he once asked me, why dont you build a model of this engine instead this old crappy 19th century engine. i said well, there is alsready a guy  making one, so i might just wait and watch your build

[Roger B]

Nicely done, Roger! 

But you're covering up all the fun stuff to watch!   

Kim

That's the problem with IC engines and especially two strokes, all the fun bits are enclosed 

[Vixen]

Nicely done, Roger! 

But you're covering up all the fun stuff to watch!   

Kim

That's the problem with IC engines and especially two strokes, all the fun bits are enclosed 

Roger,   

That problem is not confined to two strokes, It is also a problem with almost all 'modern' IC engines. That's one of the reasons I tend to make two copies. One all closed up and ready to run and the other assembled as an 'exploded' display to show off all the interesting stuff inside.

Mike

[RReid]

That's also why most of my engines have foregone even splash lubrication of the crankshaft in favor of an open crankcase and manual oiling prior to running. Works fine for small, low rpm engines that don't run long or hard. Not recommended for racey engines though.

[uuu]

A question, if you'll permit.  Why do some four-stroke IC engines, perhaps open crank, where the bearings etc are not in contact with the fuel/air mixture, still specify oil to be mixed with the petrol?

Wilf

[Admiral_dk]

They might not get enough Oil-Splash on the Cylinder bores.

Some Model Airplane Engines use that Oil in the Fuel to Lubricate everything and they are Closed and Four-Stroke .... + the really smart ones - like OS even have that Oil recirculating inside - so the excess goes back into the Inlet (between Carburetor and Valve).

Per       

oh and nice progress Roger 

[uuu]

Thanks for that explanation.

Wilf

[Roger B]

Back on this one again after all sorts of interesting distractions:

https://www.modelenginemaker.com/index.php/topic,12350.0.html

https://www.modelenginemaker.com/index.php/topic,12379.0.html

https://www.modelenginemaker.com/index.php/topic,12381.0.html

I am still working through the engine structure, crankcase and engine bearers. There are still lots of holes to drill and tap and lots of collisions with other parts to avoid 

[Kim]

Nice to see you making some progress on your engine, Roger! 

Kim

[RReid]

Better interesting distractions than the other kind! Looks like some good progress has been made though.

[Roger B]

Thank you both 

A quick check to make sure I could get to the grub screws that hold the crankshaft in place and then more drilling and tapping of the plates that make up the engine structure.

Unfortunately, I broke a 2.2mm drill in the end of one of the side plates. This is a slightly chewy aluminium and I had already broken one drill today. That was in a through hole so I could get the broken bit out fairly easily. This one was in a blind hole and unlikely to be removeable I thought. I could redrill in another place and plug the original so in any case it was salvageable.

With some teasing with a scriber and a very fine pair of Lindstrom needle nosed pliers I was able to remove the broken piece and finish the job as planned.

The side plates were too long to fit in my tapping rig so I had to tap all 8 M2.5 holes by hand, luckily without mishaps 

[cnr6400]

  Glad you got the broken drill out Roger. No fun to deal with those, or small taps either.