Stuart Triple Expansion Engine

[rhankey]

I think you are in error on the 30/15 eccentric advancement. The HP is 90+30 while the LP and IP are both 90+15.

Good catch. Right you are, and I have edited my response so it doesn't mislead anyone else. Good luck with your ongoing adjustments.

 

[steamedlou]

Well that's just frustrating as hell!!! Adjusted all the valves at least HP and LP, and adjusted all the eccentrics per the previous posts. Even found the IP eccentric 180 degrees out. Was very excited about hitting it with steam. End result this morning? NOTHING OR WORSE! Went from running on two cylinders in on direction to not running at all. not even one revolution on its own. Something is wrong here. With non adjustable symmetrical eccentrics this should be a total no brainer. Think I better put it aside for a few days. Throwing it across the room would do terrible damage to my hardwood floors.

 

[steamedlou]

The post I put on a few minutes ago was premature. It runs! I had neglected to notice that when I rotated the IP concentric 180 degrees, it reversed the valve operating. Went back and switch them on the reverse link. and now the engine runs in forward and reverse at 25 psig. a little halting ever so often, but does run. lol then it stopped. and I haven't got it again. maybe some water logging or something maybe in the LP area. but anyway it does run now.

 

[Alec Ryals]

The post I put on a few minutes ago was premature. It runs! I had neglected to notice that when I rotated the IP concentric 180 degrees, it reversed the valve operating. Went back and switch them on the reverse link. and now the engine runs in forward and reverse at 25 psig. a little halting ever so often, but does run. lol then it stopped. and I haven't got it again. maybe some water logging or something maybe in the LP area. but anyway it does run now.

Good Job, it will be awhile before I'm at your point.
Alec

 

[kilocharlie]

Just a line from an engine machinist...1) Know "firing" sequence 2) locate TDC for #1 piston - on the "firing" revolution, NOT valve rock-over, if applicable 3) set the timing for cams, valves, spark / injection device, etc. - the complete system - to "fire" position, 4) "dry" turn the engine by hand with any spark devices grounded to check for valve clearance - now is a good time to use the playdough ball method to check valve clearance 5) remove playdough and run through final check for first start-up through run-in 6) it is often advisable to run in the engine under a good, healthy load right off the beginning if seating piston rings is significant to the application. This is often more significant than cam break-in, which occurs simultaneously if done correctly.

A continuity tester can be used to exactly set contact breaker points, distributors, other electrical devices - likewise a vacuum / pressure tester can be used to set valve opening to the last half-degree or better, depending on valve seal.

Good Luck!

 

[Alec Ryals]

Just a line from an engine machinist...1) Know "firing" sequence 2) locate TDC for #1 piston - on the "firing" revolution, NOT valve rock-over, if applicable 3) set the timing for cams, valves, spark / injection device, etc. - the complete system - to "fire" position, 4) "dry" turn the engine by hand with any spark devices grounded to check for valve clearance - now is a good time to use the playdough ball method to check valve clearance 5) remove playdough and run through final check for first start-up through run-in 6) it is often advisable to run in the engine under a good, healthy load right off the beginning if seating piston rings is significant to the application. This is often more significant than cam break-in, which occurs simultaneously if done correctly.

A continuity tester can be used to exactly set contact breaker points, distributors, other electrical devices - likewise a vacuum / pressure tester can be used to set valve opening to the last half-degree or better, depending on valve seal.

Good Luck!

But This is a diffrent animal.

 

[kilocharlie]

I'm sure it is - I'd never heard of it before I read this thread, and still have no idea if it is a steam engine, a heat engine, and I.C.E., or what? I was just hoping the thought sequence might help...triple expansion timing sounds like a challenge, but every engine I've ever timed had a very mechanical reason it was timed the way it was...no magic

 

[steamedlou]

lol no magic, just different planet I think sometime. Speaking of different planet. I just did a buy it now on a Coomber rotary steam engine on ebay. now thats different. not sure one has ever been on there for sale before.

 

[kilocharlie]

Off-topic, perhaps, but I developed an 8-stroke cycle engine that was denied a California Dept. of Energy grant on grounds that they were no longer funding internal combustion engine research. The timing challenge was valve timing, which I solved by using very long-stemmed valves to keep the heat at one end, and let the crank trigger time it with solenoids instead of a camshaft.
I do usually consider (modern) Atkinson-cycle engine (used with electric / fossil fuel hybrids) valve timing and stroke volume % when designing an engine. Efficiency has become as important as power production lately, and I am considering a design that adjusts from Atkinson-cycle to Otto-cycle when more power is needed, and back as fuel efficiency becomes the priority, this aimed at power-glider aircraft use.
My current effort at a Stirling-cycle engine has variable compression and other will possibly be classified as a Delta-type Stirling, as it is somewhat different from the other three types.

 

[Alec Ryals]

Hello All,
Well I'm now making pistons and the piston rods the drawing shows the smaller space in the pistons at the top but the rod does not fit right unless turned around besides there is no room for the nut on the smaller side.
Has anyone ever run across this.
Thank You Very Much\
Alec Ryals

 

[rhankey]

Hello All,
Well I'm now making pistons and the piston rods the drawing shows the smaller space in the pistons at the top but the rod does not fit right unless turned around besides there is no room for the nut on the smaller side.
Has anyone ever run across this.
Thank You Very Much\
Alec Ryals

Alec, I assume when you say "does not fit right", that something is hitting something else. If so, exactly what is hitting what?

I am guessing when you say things are not fitting right, that the outer rim of the piston is hitting the cylinder covers unless you turn the cylinder over. If so, I would guess the 8 vertical columns, the piston rods, or the connecting rods might not be of the correct length, or the crankshaft is sitting too low or high relative to the bottom of the columns. There are a number of key measurements that come together to determine where the pistons will sit. At this point, if the pistons fit better being fitted upside down, that might be the simplest solution, otherwise you might find you have to remake or adjust other parts.

If I remember correctly, I was able to make the pistons and rods exactly to plan and when assembled the piston was perfectly centered within the cylinders - no interference with top or bottom cylinder covers. The inset depths on the top and bottom of each piston where the piston rod attaches is clearly specified in the plans, and I know I did not need to mess with that at all. The diameters and the secondary depths of the profiling for the tops and bottoms of the pistons was not specified, but it mates with similar profiling in the top and bottom cylinder covers. I seem to recall making a very tiny deviation from plan for the bottom HP cylinder cover, as I didn't like how little metal they specified to leave where the rod passes through.

The only errors I found on the current triple plans, was that they specified and supplied shorter bolts for the drag links than were actually needed. I think that was because at some point they change a dimension in the drag links, but forgot to update the length of the bolt accordingly. Other than that, so long as you stick exactly to the plans for all key dimensions, everything fit perfectly.

 

[Alec Ryals]

Thanks, but I have not machined yet but my question is the top of the threaded piston rod is .375 and the pistons are showing .250 thickness hence if asambled like the print the threaded portion of the piston sticks above the piston - here are the drawings of the error that I don't know which is correct.
Thank You
Alec Ryals

 

[Alec Ryals]

Here are two photos of were the error is.
Thank You
Alec Ryals

 

[barnesrickw]

It would stick above by 1/8th" is there a nut that keeps it in place? I think most steam engines have room at the top of their stroke. Will this 1/8" cause it to strike the head?


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[barnesrickw]

My math was wrong. Connecting rod sticks above cylinder head by 1/16".


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[rhankey]

Yes the piston rod does extend 1/16" above the top of the piston. That is ok, as it fits within a recess that you machine into the upper cylinder cover, which is best depicted in the cross sectional diagram. The recess in the cylinder cover needs to be of sufficient diameter for that of the piston rod lock nut.

 

[Alec Ryals]

Why does the drawing not show this? the piston rod sticking out the top of the piston 1/16" are the deminshions correct !
Alec

 

[rhankey]

Why does the drawing not show this? the piston rod sticking out the top of the piston 1/16" are the deminshions correct !
Alec

The drawings do show the piston rod extending 1/16" above the top of the pistons... And from a math perspective, the piston rod has a 3/8" threaded section. The threaded section of the piston is 1/4", the top of which is 1/16" below the top of the piston. So when you do the math (3/8" - 1/4" - 1/16" = 1/16"), the piston rod extends 1/16" above the top of the piston.

 

[barnesrickw]

The drawings do show the piston rod extending 1/16" above the top of the pistons... And from a math perspective, the piston rod has a 3/8" threaded section. The threaded section of the piston is 1/4", the top of which is 1/16" below the top of the piston. So when you do the math (3/8" - 1/4" - 1/16" = 1/16"), the piston rod extends 1/16" above the top of the piston.

That's how I did it. They can't dimension to the rod on that view, but they could have given an inside assembly section view or note to show this.


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[barnesrickw]

Wait, just looked at the picture, and they did just that.


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