# Two cylinder, double acting, horizontal engine???



## Brian Rupnow (Oct 17, 2008)

Okay people, help me out here please. I would like to build a twin cylinder horizontal engine in which the cylinders are double acting, probably two 4" diameter flywheels, and possibly a set of crosshead guides if I need them. I want the engine to have either sliding valves similar to the famous "beam engine at double scale" or else poppet valves ala Chuck fellows. I want to build it from bar stock, and I want to offset the crank journals at 90 degrees so it self starts. I don't want to pay for any plans. ---Surely thats not asking too much, is it??? I've been looking at the cylinder, valve, and piston on the "beam engine at double scale" and thinking---"Why couldn't I take a larger single block of brass, and bore a cylinder and valve hole on each side of it, and mount the block so the cylinders are horizontal and"---"This would of course require two seperate eccentrics, and a single built up crank and---" Yes, Ive nearly got it designed in my head. Any thoughts or comments on this flight of fancy?---Brian


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## Twinsquirrel (Oct 17, 2008)

No input as usual from my end but the image I have in my head of it is bl**dy gorgeous!!


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## wareagle (Oct 17, 2008)

Brian Rupnow  said:
			
		

> Yes, Ive nearly got it designed in my head. Any thoughts or comments on this flight of fancy?---Brian



Thoughts... Go for it! That's my thought.  ;D

So for some other thoughts; The beauty of designing your own engine is you can utilize different componets and ideas from other design as you see fit. Based on what you describe, I don't at all see why it wouldn't be a successful project. Build it in the computer first, and you will save yourself some grief! 

Are there some details to be worked out? Oh yeah, but all of these engines have been at that stage at one point or another. You can do it!


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## Brian Rupnow (Oct 17, 2008)

Well, I think the cylinder block would look something like this---right now its set up at 3" center to center of the cylinders, however as the design progresses, that can be easily altered with my software. You can see that I have rotated the air inlet ports so that they will be pointed up---thats so I can join them with a common manifold.


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## Brian Rupnow (Oct 17, 2008)

The cylinder heads would probably look like this. Since there will be a lot of side forces acting on the piston rod, I have bumped the diameter up to 1/4" fom the original 1/8", so have enlarged the holes where the rods come out though the heads. I have also moved the valve bores 1/8" farther away from the cylinder bores to give me a bit more room.


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## max corrigan (Oct 17, 2008)

Brian i don't know if this would help but if you look at my first effert (notice the spelling) which i posted, it is a stuart S50 double acting horizontal engine with the slide type valve which you can just see in one picture, the cover is removed, i would think you could double it up and add the crank shaft you were refering to without to much trouble' it is a nice looking engine and runs well, and would look great as a twin! and being you are not useing castings it would not look like the Stuart "Score" which is pretty much the same as a S50 but with twin cylinders and a single flywheel either way it might give you an idea!
Regards Max.............


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## CrewCab (Oct 17, 2008)

Brian Rupnow  said:
			
		

> I don't want to pay for any plans.



Tight 
	

	
	
		
		

		
		
	


	




 ;D : .................. only joking Brian 

In my case I think plans would be a necessity, given your background I suspect you can design it as you can go along, the idea's so far seem good ........... tell me though (as I'm sure there is a good reason ............. it just seems to escape me at present  ) ......... why are the cylinders so far apart ......... I'm assuming the flywheels are outboard btw.

CC


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## Maryak (Oct 17, 2008)

Brian,

Attached is a PDF of a simple twin, reversing engine which I had a fiddle with a few years ago to help me learn 2D CAD. It's based on a Paddle Steamer Engine hence the gear on one side. I designed it with a view to using bar stock.

Just a thought ???

Best Regards
Bob 

View attachment QuickCAD.pdf


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## GailInNM (Oct 17, 2008)

Brian,
Attached video of my little donkey engine that I built about 10 or 12 years ago. It is much smaller than you like, but I MAY still have the CAD drawings on the computer somewhere and they could be doubled as a starting point if you like the engine. It could easily be adapted to your single cylinder block. Maybe give you some ideas of at least one approach anyway. 
Gail in NM,USA
[ame]http://www.youtube.com/watch?v=ZpwFdimoCsU[/ame]


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## CrewCab (Oct 17, 2008)

Gail .......  8) ..... just superb :bow: ............... music's nice too 

CC


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## Brian Rupnow (Oct 17, 2008)

Gentlemen--Thank you so much. Outstanding engine, Gail, and nice plan Maryak. Crewcab--The cylinders are that far apart as a "starting point" only.--I won't know untill I get deeper into the design how far apart they really need to be. I have designed the cylinder block in such a manner that one keystroke will change that center distance to what it needs to be, when I get that far. I know the shape of the cylinder block in all other respects except for that center to center distance, and those dimensions are "locked".----thats one of the nice things about 3D cad. I will probably finish this design over the next 2 or 3 days, and will post it as I develop it.--Brian


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## Brian Rupnow (Oct 17, 2008)

And here we are with piston and rod assemblies. The pistons are the same as the piston in the "Beam action at double scale", except they are threaded for a 1/4"-20 rod instead of the previous 5-40 thread. The rod is the same length as the beam engines, but bumped up to 1/4" diameter to compensate for the side loading that will result from having an additional link between the end of the piston rod and the crankshaft throw. The end opposite the piston has been bumped up to 3/8" wide to accomodate the 1/4" piston rod.


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## chuck foster (Oct 17, 2008)

hey brian................do you have wood working machines in your shop?????

cause at the rate you are going you are going to need a big display case for all your models  ;D :big:

chuck


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## max corrigan (Oct 17, 2008)

Gail that is a beautiful one hell of a little engine does it run ok on steam? messy i know but it gives that something that these designs were meant to be! or maybe i'm wrong we have easily electrically or whatever, pumped air nowadays, so in them steam days,had they known, i think they would have gone along on these lines also, and would have come up with some great adaptions and inventions without the use of cads and such! food for thought!! but! where would they get pumped air from? what was that song theres a hole in the bucket dear liza dear liza
Good luck Max.............


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## Brian Rupnow (Oct 17, 2008)

Well there! That enough foolishness for one day. Now that I know how much space I have between the connecting rods, I was able to shrink the center distance between cylinders from 3" down to 1 5/8". I had to design the connecting rods and attach them to the piston rods, then leave enough room between them for a crankshaft center bearing. thats what determines the center to center of cylinders.


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## Brian Rupnow (Oct 17, 2008)

Jeez---Once I get started with this stuff, I can't leave it alone!!! I have modelled a built up crankshaft with the "throws" at 90 degrees to each other so the engine should self start. I just went through some rather amazing math to get the piston stroke exactly centered between the valve ports in the cylinder, when the crank is at its 2 extremes of rotation. now I really gotta quit!! Its past my bed time..


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## GailInNM (Oct 17, 2008)

Looking good Brian. Lots of us watching to see how this evolves.

Max: The engine runs better on steam than or air. As with all small diameter cylinders on steam, it is necessary to keep the steam dry by keeping the plumbing short. If I was going to run it on steam regularly, I would replace the aluminum cylinder mounts with an insulating material to keep the rest of the works cooler. 

Gail in NM,USA


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## wareagle (Oct 18, 2008)

Brian, I see a fatal flaw in the design... It will never run with a green crankshaft. It would be fine with an orange or blue crankshaft, but the green one just isn't going to hold up.  ;D :big: 

Seriously, the design is looking great. I think you are well on your way to a cool project! Keep us updated as you progress.

BTW I feel your pain when you can't shut the old noodle down once it gets going. I have that problem myself. Especially at night when I need to be going to sleep! :


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## tel (Oct 18, 2008)

Just to keep your pot boiling Brian. here's my version. Sorry about the B&W folks, but that shot was taken for an article in AME back in the days when they didn't accept colour photos.

3/4" bore and stroke.


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## Brian Rupnow (Oct 18, 2008)

Tel--Thats a nice one. I've been wondering about crosshead guides. I see how you solved the problem. do you think they were really necessary?---Brian


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## tel (Oct 18, 2008)

Probably not Brian, but I like my engines to look like engines.


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## Brian Rupnow (Oct 18, 2008)

What a way to spend a Saturday morning. One of the things that is making me crazy is trying to figure out how long the valve actuator rod should be center to center. There is a distinct relationship between where the piston is in its cycle, compared to where the valve is in its cycle. This means there is a distinct angular relationship between the eccentric lobe and the throw on the crankshaft. If a wiser head than mine can jump in and exlplain these relationships clearly, I certainly would appreciate it.---Brian


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## Brian Rupnow (Oct 18, 2008)

So---add some bearing stands and caps, a baseplate and a spacer block, and we're nearly finished.


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## Brian Rupnow (Oct 18, 2008)

So-------


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## SandyC (Oct 18, 2008)

;D

Hi Brian,

It looks like a workable design so far, great work with the 3D.

One major thing though....... with such a long stroke you will definitely require a cross head arrangement, otherwise you will find that the piston rods will be deflected sideways thus rapidly wearing out the lower cylinder bearing, which, in turn, will cause the pistons to foul the cylinder walls. :'( :'( :'(   

You will also require some sort of steam seal (o-ring or graphite yarn) in the lower cover, around the piston rod, for a double acting engine..... which will also need the help of the crosshead guides if it is to remain steam tight for more than a few hundred revolutions.

I attach some valve timing diagrams which should give you enough info for the various locations at the critical points of the cycle.

They show a D slide valve on the (1st) main one, however, this can be exchanged for a piston valve as per the second diagram.
The timing relationship for both valve types is identical.... at least it is for a line on line valve arrangement....i.e. one with no steam lap and/or lead.

They are extracts from a series of articles I did....I am considering turning the whole lot into a small book at some time in the future. :-\ :-\ :-\ ;D ;D

Hope this helps.&#160;    :big: :big: ;D ;D ;D

SandyC

Edit..... I should add that the diagrams are for an OUTSIDE admission valve... with the exhuast in the centre.

For an INSIDE admission...everything remains the same as far as the valve timing goes, however, the direction of crank rotation will reverse.
The only other thing that would change for a slide valve type would be the need for a BALANCED slide valve...to prevent the valve lifting of the port face....NOT a problem with a piston valve. 

View attachment Fig 10 slide valve sequence with no Lap or Lead.pdf


View attachment Fig 12 Equivalent Piston Valve.pdf


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## Brian Rupnow (Oct 18, 2008)

Sandy--Thank you--That information is exactly what I needed. I did not use any rod seal on the "beam engine at double scale" that I built a couple of months ago, so I'm not 100% sure a seal is necessary The plate that bolts on where the rod exits is more thn just a 1/8" thick plate---It has a 1/2" diameter boss that extends 5/16" into the cylinder to give lots of bearing surface for the rod. I'm sure you are right about the crosshead guides, so I will look into adding them.---Brian


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## Brian Rupnow (Oct 18, 2008)

Brian Rupnow  said:
			
		

> Sandy--Thank you--That information is exactly what I needed. I did not use any rod seal on the "beam engine at double scale" that I built a couple of months ago, so I'm not 100% sure a seal is necessary The plate that bolts on where the rod exits is more thn just a 1/8" thick plate---It has a 1/2" diameter boss that extends 5/16" into the cylinder to give lots of bearing surface for the rod. I'm sure you are right about the crosshead guides, so I will look into adding them.---Brian


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## SandyC (Oct 18, 2008)

;D ;D

Hi Brian,

Ok I thought they may help.

The reason I suggested the lower seals and cross head on this engine are that it will experience far greater sideways forces than your beam engine did, since this had a much straighter push pull from the beam..... the angular forces from the crank are a great deal higher.

Something to keep in mind.

Best regards.

Sandy. ;D


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## Philjoe5 (Oct 18, 2008)

Brian,
Sorry for the late post to this thread but what you are building sounds almost exactly what I've started. It's in Work in Progress "A two cylinder mill engine under construction ". I'm also pondering the crankshaft design. Unfortunately for some reason I cannot view any of the jpeg's you've posted (anyone else having this problem?) so I can't comment on how close your design is to the one I'm working on.

Cheers,
Phil


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## Brian Rupnow (Oct 18, 2008)

Philjoe--I don't know why you can't see the .jpg's . I did look at the engine in your post, but without plans, I could not build it. Seeing as I had such great success with the "beam engine at double scale", and seeing as I design machinery for a living, I thought I would go ahead with my own design, basically "from scratch", but incorporate the things I know work well from the beam engine build.---Brian


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## Brian Rupnow (Oct 18, 2008)

In deference to SandyC who seems to know what he's talking about--I have extended the bolt-on rear piston guides (pink) to act as "crosshead guides" to help remove the bending moment from the piston rod and to aid in sealing steam (or air) from escaping around the rod at that end. I have also added a third bolt to help hold it squarely against the cylinder body. Since the "throw" on the eccentric that runs the valves is considerably less than the "throw" on the crankshaft, I am not too concerned about crosshead guides on the valve rod---Besides which, if I did that I would have to make the entire base longer and move the crankshaft centerline out farther away from the cylinder body.


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## Brian Rupnow (Oct 18, 2008)

Sandy--I have a question for you.   In the .pdf attachment "fig.12 equivalent piston valve" the diagram half way down the right hand side in the center states that the "eccentric offset (rad)=steam port width", and the diagram at the bottom of the page shows that the length of the large diameter on the steam valve should be "same as steam port width". When I designed the "beam engine at double scale" a few months ago, I based my design on one of Elmer Verburgs engines http://www.john-tom.com/ElmersEngines/24_beam.pdf I followed the relationships given in the Elmers beam engine .pdg, and his are not equal. In his engine designed incorrectly, or am I missing something here. I am going to use the same valve arrangements and relationships in this new engine as I did on my beam engine, and if making a small change can make it run better/more efficiently then I will make that change in my design. This whole science of valve timing is a bit of a "black art" to me right now, but I am learning.--Brian


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## SandyC (Oct 18, 2008)

;D ;D

Hi Brian,

Well now, that puts a different light on the subject....... HOPE YOUR A GLUTTON for PUNISHMENT..... :big: :big: ;D ;D

The answer lies in the the valve on the ELMER engine.

It is designed with both OUTSIDE and INSIDE LAP.... I was hoping to keep away from that at this stage cos it complicates things for you....not that you won't grasp it, it's just a bit more difficult to understand what is going on.

The valve and eccentric dimensions shown on my previous drawing relate only to a slide valve or a piston valve which has neither INSIDE or OUTSIDE LAP, in other words, the steam and exhuast edges are in line with the cylinder port edges with the valve in its MID position.

I took a quick look at Elmers drawings and it would appear that his eccentric is slightly less in throw than I would have made it initially, given the port and valve land dimensions, however, I have not studied the effects of the angular linkage at this stage and this will most certainly make a difference.

Normaly, for a directly driven valve, the eccentric offset would be = to port width +&#160;the LAP, since this is the distance the valve would need to travel to fully open the port.
The total valve travel, to achieve the identical, but opposite position for opposing piston ends, would be 2 x port width + 2 x lap.
For an indirectly driven valve, (i.e. one not directly connected to the eccentric strap) then the length ratio of any lever arms or links will have an effect, as will any angularity effects, and therefore these must be taken into account. This could lead to the eccentric offset being larger or smaller than for the direct connection dimension.

The other major effect of LAP is to alter the angular advance of the eccentric relative to the crank.

The INSIDE LAP effects the exhaust timing and compression phases.

I have attached a few more pages from my articles which explain the terms and also shows the timing of a valve with lap.
This should get you thinking. ;D ;D ;D ;D :big: :big: :big: :big:

Hope you can get to grips with this.

Best regards.

Sandy&#160;   ;D 

Edit.... re-worded eccentric offset and valve travel statement to make more clear. 

View attachment Fig 11 Slide valve sequence with lap and lead.pdf


View attachment Fig 11a Slide valve sequence with lap and lead ctnd..pdf


View attachment Fig 9 Slide valve and eccentric.pdf


View attachment PDs_ 5.pdf


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## SandyC (Oct 18, 2008)

And one more attachment which might help understand the diagrams and documentation a bit more.

Sandy.   

View attachment Hyp ind diag..pdf


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## Brian Rupnow (Oct 18, 2008)

[size=10pt][size=10pt][size=10pt][size=10pt]*Awright!!! Enough of this development phase. I have moved over to the "A work in progress" thread and started to build this thing.---Brian*[/size][/size][/size][/size]


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