They do exist...

[jackjcc]

Whose the brain child for this beast?

Sent from my iPhone using Tapatalk

 

[Erock]

That is cool. I'm thinking the one on the left is going to burn up though

 

[happysaws]

Looks good, but it also looks like one recoil is pulling over 2 engines... the user will need some serious arm to pull that one over.

I wonder if both pistons fire at the same time, or if they fire 180° apart..?

What if one power head runs faster than the other...?

Okay, I'm all done for now [emoji16]

 

[radio]

Very interesting. I have never seen anything like this. I would imagine that both heads are run off of one ignition system so that they would run in sync. If they had independent flywheel/coils then they could run at different speeds and trash each other pretty quickly.

 

[hedge hog]

Wow!


Sent from my iPhone using Tapatalk

 

[HarleyT]

I have worked on a couple of these mowers, they use a central clutch/flywheel setup to handle the differring engine's input.

 

[Wood Doctor]

This is an engineering nightmare. I've often thought that Stihl should have made a 2-cylinder model rather than the 090, but it never happened. A V-twin would have probably sold rather well.

I imagine he staggered the firing order 180 degrees so that you get two explosions per RPM. Anyway, things like this are interesting even if they have to be rebuilt every three minutes of operation -- kind of like a dragster.

 

[mgr]

I see that pic before. Don't now on what site.
The only thing that i remember is that the second saw starts working when the clutch from the left one engages.

 

[jackjcc]

There was one more picture, found it on Facebook.

Sent from my iPhone using Tapatalk

 

[cus_deluxe]

Wow, regardless of performance i bet that thing sounds pretty rad!

 

[HarleyT]

The mower has an rpm gauge and I think a vacuum gauge on each engine, would be nice to see more info on the saw, like fuel and ignition setup...

 

[1Alpha1]

Obviously a novelty, rather than something actually used for what it (they) were intended for.

 

[backhoelover]

I have worked on a couple of these mowers, they use a central clutch/flywheel setup to handle the differring engine's input.

View attachment 561309

what kind of mower is that @HarleyT

 

[HarleyT]

Dixie Chopper

 

[Wood Doctor]

I've seen that pic before. Don't now on what site.
The only thing that i remember is that the second saw starts working when the clutch from the left one engages.

If that is the case, how does the clutch know when to exactly start the second crankshaft to begin rotating and then fire? The cylinder explosions have to be synchronized along with the fuel/air intake. Clutches have few brains. If the power explosions are off few degrees, what you have created is a 2-cylinder clunker.

 

[82F100SWB]

It would be very odd for both powerheads to have a clutch and not have the cranks joined directly. That would be asking for problems. As long as the cranks are joined and the throttles synced it would make no difference if there is a common ignition or if they are separate.

If you are familiar with snowmobiles the Yamaha VMAX 4 is essentially a pair of 2 cylinders with a common crankcase.
Each engine has its own crank, y-pipe, airbox and boost bottle. The cranks meet in the middle and are geared to a common output shaft. Ignition is common.

 

[pioneerguy600]

Here is an older thread we had on here about these saws,

http://www.arboristsite.com/community/threads/norway-trade-fairs.115652/

 

[Wood Doctor]

It would be very odd for both powerheads to have a clutch and not have the cranks joined directly. That would be asking for problems. As long as the cranks are joined and the throttles synced it would make no difference if there is a common ignition or if they are separate.

If you are familiar with snowmobiles the Yamaha VMAX 4 is essentially a pair of 2 cylinders with a common crankcase. Each engine has its own crank, y-pipe, airbox and boost bottle. The cranks meet in the middle and are geared to a common output shaft. Ignition is common.

For any multi-cylinder engine, ignition timing is paramount if they are to have balance and last. If they fire ten or 20 degrees off crank shaft balance, you have created a clunker.

 

[SEAM]

They probably run independently with the clutch drum of the left (starter) saw attached to the crank shaft of the right saw.
I do think there are problems with cooling the right unit, though...

 

[Naylor649]

That's insane looking!