Understanding the adjustment of a compound

A special section just for steam engines and boilers, as without these you may as well fit a sail.
mcandrew1894
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Re: Understanding the adjustment of a compound

Post by mcandrew1894 » Thu Apr 22, 2010 12:54 am

Hi Piet,

Valve travel

Valve lap ( steam lap and exhaust lap if there is any exhaust lap)

Valve lead at top and bottom dead center (This with the steam lap will give us the angle of advance. The lead is the amount the steam port is open with the piston at dead center.
Take these numbers for ahead and astern....we will see if its even.



Width of the steam ports

Width of the exhaust port

Width of the bridges between the ports.

Do this on the HP and LP sides. Then we will know where we are anyway

It would be good to know what the volume of the reciever is.....filling it with water and then weighing the water is a good way to do that pretty accurately.

From this known point, we can start to think about the new gear and compare the motion/movement of the new gear to the old one. That way we will have an idea if we are getting better or worse as we design it.


A box link looks like a common bar link with two curved bars. The difference is the inside face of the bars has a machined groove that a bearing fits into. I have that on my engine and I did if for a reason. My engine runs about 600 rpm. There is no way in hell I can get an oil can spout on an oil hole in a moving link at that speed. With the bearing inside, capilary action wicks the oil in, and the enclosed form hangs on to it longer. I just squirt a little on the top side of the link and it goes right where I want it.

Its origins as I have been told were in our early steam navy on the Pinance and cutters.

It would appear the Engineers 3rd class where filing the link slots on conventional links longer trying to get better valve events and generally screwing up the engines.

This link is tamper proof....or at least tamper resistant.

Image
It is a true pain in the backside to make accurately....it requires a fixture and a rotary table on the mill.....not for everyone.....but I like it.
Heres a sketch of the information I think we need to start with anyway.
Image

Dave
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Re: Understanding the adjustment of a compound

Post by mcandrew1894 » Thu Apr 22, 2010 2:25 am

Oh and Cool Boat!

What do you do on her?

Dave
piet schuurs
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Re: Understanding the adjustment of a compound

Post by piet schuurs » Thu Apr 22, 2010 6:21 pm

Dave I don't get the scans uploaded here.
So I give the links to find them on my site.

http://members.chello.nl/p.schuurs/HP.gif

http://members.chello.nl/p.schuurs/LP.bmp

I hope this is what you guys want to have, if not, let my know

To measure the volume of the receiver is a little bit diffucult, the engine is stil mounted in the boat. So I only can give you the dimensions.

Ohh, by the way Iám her captain and she is the pressentation vessel of the
Port Authoryties Rotterdam.
mcandrew1894
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Re: Understanding the adjustment of a compound

Post by mcandrew1894 » Thu Apr 22, 2010 11:40 pm

ey ey captn'!

That's the stuff I was looking for.

I'll start on it.

Dave

Dave
piet schuurs
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Re: Understanding the adjustment of a compound

Post by piet schuurs » Fri Apr 23, 2010 9:28 am

Come on chief there is no hurry take your time.
piet
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Re: Understanding the adjustment of a compound

Post by mcandrew1894 » Fri Apr 23, 2010 9:51 am

I'll have to "nibble" at it as lately I have been working a lot of hours piet.

I have some ideas, but we need to quantify what you have first.

Dave
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Re: Understanding the adjustment of a compound

Post by mcandrew1894 » Fri Apr 23, 2010 11:24 pm

Jorgen,

I have not forgot about you my friend...I am reviewing your spreadsheet....I'll do some this evening with a bit of "brew"....been a long week. :roll:
Dave
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froya66
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Re: Understanding the adjustment of a compound

Post by froya66 » Sat Apr 24, 2010 9:19 pm

No problem – just take your time.

As I think I have said before– my spreadsheet is no rocket science.

If you can come up with a simple way to more precise handle the average compression and pre admission in relation to different cut offs, without actually designing the valve and reverse gear details, I should be happy.

Regards
Jørgen
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Re: Understanding the adjustment of a compound

Post by mcandrew1894 » Tue Apr 27, 2010 1:03 am

Piet,

Can you confirm the numbers for your LP chart? Port openings of 5.04mm and 5.84mm?

Additionally, you probably don't know this, but if you do, the angle of advance for the eccentrics would be great! :D ...Not knowing that, the lead when the piston is at top dead center would allow me to calculated the angle of advance.

Dave
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Re: Understanding the adjustment of a compound

Post by piet schuurs » Tue Apr 27, 2010 6:53 am

Hi Dave,
Aspecialy on the LP that are the correct numbers.
The LP receiver is easy to reach in the boat and very easy to take the measurements.
Nice that my feeling, as a beginner, about the performens on the engine is oke, she runs nice whit little use of steam.
So again Dave, take your time there is no hurry.
Take care Piet
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