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brian Rupnow
12-06-2012, 08:02 AM
As I struggle along with my sawmill build, I think about the engines I have available to run it. My only water cooled engine is the Kerzel Hit n Miss I built a few years ago. This of course leads me to thinking of twin cylinder water cooled industrial engines (i.c. of course). And this in turn made me think, I don't believe I have ever seen a twin cylinder water cooled hit and miss engine. Does anyone out there know of plans or a link?
----Brian

Lew Hartswick
12-06-2012, 08:20 AM
When I read the title I said to my self: I never even heard of such let alone
saw one. :-) I think it would be "difficult" to organize the governor on that.
BUT if anyone has seen or built one I'd sure be interested it seeing/hearing
about it.
...lew...

JCHannum
12-06-2012, 08:48 AM
Here you go;

http://www.youtube.com/watch?v=RRR8z446a9Q

http://www.youtube.com/watch?v=APT8A15Rx6E

The second, opposed twin might be a simpler build as I imagine you could use the same cam and trip mechanism to operate the intake valves. The side by side could be a bit more complex.

Edited to add, this video refers to the Dempster as a two cycle;

http://www.youtube.com/watch?v=dxlzbxcIps0

A.K. Boomer
12-06-2012, 10:47 AM
When I read the title I said to my self: I never even heard of such let alone
saw one. :-) I think it would be "difficult" to organize the governor on that.
BUT if anyone has seen or built one I'd sure be interested it seeing/hearing
about it.
...lew...

When I first read the Title I said "why"

I mean it's a hit and miss...
Your already only firing one cylinder intermittently and basically not using its full potential - why would you want to introduce another "sloth"

talk about an entitlement program... might as well throw in a couple others just for some extra "parasitic drag" ???????????????????

Mcgyver
12-06-2012, 11:02 AM
Jim, isn't that something, i'd not seen one like that before


When I first read the Title I said "why"
??

I'd guess because you need more power/balance on the power cycle of the machine? - ie sawmill (circular blade style)

A.K. Boomer
12-06-2012, 11:17 AM
Generally with hitNmis the flywheel is so grossly out of proportion that power strokes (or lack there -of) are almost a non-issue...

another words - If your taxing a hitNmis so that it does not quite have the balls to pull it off while running at full capacity then you really should not be thinking of another cylinder, you should be thinking of a larger hitNmis...

In keeping with tradition that is - and by that respect I mean getting the biggest uncomplicated fuel saving (when not working at full potential) bang for your buck.

JCHannum
12-06-2012, 11:36 AM
I would have said there were none either, but a short search turned up those two. I can see the advantages of a twin as scaling up a single cylinder can result in a pretty massive engine.

The twin also results in smoother power delivery. The hit & miss miss only kicks in when the engine is "idling". When under load, it will hit on every stroke if set up properly.

Stuart Br
12-06-2012, 11:59 AM
Bolinder from Sweden were another manufacturer. Mostly deployed as marine engines
http://www.oldengine.org/members/diesel/Marine/bolinder.htm

A.K. Boomer
12-06-2012, 12:04 PM
I agree in some ways. but lets face it - these things will never be Ferrari's lol

Part of the great efficiency's of these engines are because they run at such low RPM's
You can reduce the reciprocating mass along with bore and stroke to achieve higher RPM's but then your taking a hit in torque and also efficiency...

If the main goal is smoothness then a larger flywheel will remedy the situation - you can even gear them and keep them smaller but now your going to take a hit in efficiency transfer...


The best applications that iv ever seen the HitNmis used for was for oil wells,

they are the perfect machine for the job.
they will run on half bat urine if that's all you got - pipe them up to the natural gas fumes from the well itself and let them rip,
if your counter weights on the well head are a little off no worries as the engine will coast the entire duration of the re-coil stroke, then hunker down for a few beats when pulling the load - it's a beautiful thing to watch... and even more so somewhat hypnotizing to listen too...

Mcgyver
12-06-2012, 01:09 PM
I agree in some ways. but lets face it - these things will never be Ferrari's lol

...

just about every make of them I've ever seen completely agrees with you (every one until toda lol)...so I'm not arguing...just speculating why someone might have thought of going down that path

brian Rupnow
12-06-2012, 02:54 PM
Many folks don't fully understand just how a hit and miss angine works. When there is no real power demand on the engine, it begins to rev up.--This increase in RPM is what triggers the "miss" cycle by disengaging the exhaust valve, via the governor. As a consequence of this, the engine creates no vacuum on the intake stroke, so no fuel is pulled thru the intake valve, the engine can't fire with no fuel, so the rpm's drop off, disengaging the governor and letting the engine draw in fuel at the intake valve and fire again. However, when a power demand is made of the engine, the rpm doesn't pick up---it just produces power on every second stroke like any normal 4 cycle engine. The power demand is what keeps the engine from revving up and engaging the governor. The massive flywheels are there simply to let the engine coast for a long time by inertia when it is in the miss cycle. If however, the power demand is too great for the size of the engine, it will never go into the miss cycle, and will perform like any other 4 cycle engine. And if its too underpowered for the load being placed on it, it will soon overheat the water in the cooling water reservoir and the engine will quickly break down just like any other engine which is underpowered for a specific application. Hit and miss engines don't work well in a situation where a lot of changes in rpm are required----They are more of a constant speed engine which can react to varying torque requirements, but not speed changes. Yes, probably a bigger single cylinder would address the problem, but if I build an engine, I like to build something functional but unique. I have never seen a twin hit n miss engine either---Didn't even know if they existed.----Brian

A.K. Boomer
12-06-2012, 03:25 PM
It will be unique for sure Brian,
and not quite double the work but close, if your going to make that leap you might as well go opposed - they are just one more step closer to uniqueness and coolness :)

brian Rupnow
12-06-2012, 03:36 PM
AK boomer. I don't plan on building one----At least not right away. I was just curious if there even was such a thing.---Brian

A.K. Boomer
12-06-2012, 04:02 PM
I think the main thing to consider with these types of engines and why most of them are the way they are is the fact that they are basically stationary slugs.

anotherwords most all just stay in one spot so once all the oversize colossal parts are moved into place and fitted then it's a done deal - just get one massive simple one cylinder design with a flywheel the size of a truck wheel and your good to go,

Now - imagine if you had to propel a vehicle with one, and then stop all that mass for a stop light and accelerate it again,
If you were forced to use hitNmis engines in this application you can bet they would be multi-cyl. and far lighter...

John Stevenson
12-06-2012, 04:22 PM
I don't believe I have ever seen a twin cylinder water cooled hit and miss engine. Does anyone out there know of plans or a link?
----Brian

Harley Davidson but not water cooled.

sasquatch
12-06-2012, 06:01 PM
Love those flywheel engines.

Quite a few missed the scrap collectors to supply WW 2, and fortunately a large number of them are still being restored, and run by collectors.
The simplicity of these engines, and MASS have allowed them to run for generations, with general care.

Stuart Br
12-07-2012, 03:46 AM
Many folks don't fully understand just how a hit and miss angine works. When there is no real power demand on the engine, it begins to rev up.--This increase in RPM is what triggers the "miss" cycle by disengaging the exhaust valve, via the governor. As a consequence of this, the engine creates no vacuum on the intake stroke, so no fuel is pulled thru the intake valve, the engine can't fire with no fuel, so the rpm's drop off, disengaging the governor and letting the engine draw in fuel at the intake valve and fire again. However, when a power demand is made of the engine, the rpm doesn't pick up---it just produces power on every second stroke like any normal 4 cycle engine. The power demand is what keeps the engine from revving up and engaging the governor. The massive flywheels are there simply to let the engine coast for a long time by inertia when it is in the miss cycle. If however, the power demand is too great for the size of the engine, it will never go into the miss cycle, and will perform like any other 4 cycle engine. And if its too underpowered for the load being placed on it, it will soon overheat the water in the cooling water reservoir and the engine will quickly break down just like any other engine which is underpowered for a specific application. Hit and miss engines don't work well in a situation where a lot of changes in rpm are required----They are more of a constant speed engine which can react to varying torque requirements, but not speed changes. Yes, probably a bigger single cylinder would address the problem, but if I build an engine, I like to build something functional but unique. I have never seen a twin hit n miss engine either---Didn't even know if they existed.----Brian

Brian, the Bolinder Semi-Diesel hit and miss works on a slightly different principle. The governor disengages the fuel pump. So a miss cycle runs without any fuel being injected. Same result though. I haven't seen a two cylinder Bolinder running. The single cylinders are mesmerizing to watch and sound fantastic. Years ago I played a very small part in helping to restore a narrowboat which was Bolinder powered. The hit and miss sound is very clear in this video http://www.youtube.com/watch?v=_jp_m1OiM9E

Edit
Here's a video of a twin
http://www.youtube.com/watch?v=UNAiK60TDLw