steam4ian
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One good turn deserves another
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Post by steam4ian on Sept 4, 2016 11:07:35 GMT
Yes!
A pump needs hysteresis provided by
A compressed spring and latch
A toggle mechanism
A pilot valve operating a shuttle
A second steam cylinder (Duplex pump)
You asked elsewhere about the ratio between steam and water cylinders. Looking at dimensions provided in designs here it seems that about 1.5 to 1 is a typical ratio.
Ian
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Post by suctionhose on Sept 4, 2016 11:58:07 GMT
I don't know why we are talking about springs and over centre devices or eliminating the shuttle or .......
If any of these things were the solution - they were mostly proposed by eminent model engineers of 30 years ago - would we be discussing the lack of reliability of these things here and now in 2016?
Google Westinghouse Air Compressor. Images. Sectional views appear.
Take the proven design (of 2016) whereby the pilot is a slide valve in a circular bore, the shuttle is modified to be pushed both ways by live steam and you're on the track to making a reliable pump.
Let the discussion be on where the ports go, how to make them, what to use for seals etc
No pump I ever saw worked hour after hour without missing a beat using those over-centre spring arrangements. We used to ask the owners "does the pump work well?" "Er Ah Well, not today. Maybe later..."
Yet these days there are pumps everywhere that run like a Swiss timepiece. Someone, somewhere has moved on from 1984. So should we....
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Post by joanlluch on Sept 4, 2016 15:02:41 GMT
Hi Ross,
Please do not forget that in my case you are talking with an absolute novice. I began to look closely at steam pumps just one week ago, so you can't assume I will know everything. Yes, just one week ago. Learning is one of the purposes for me posting here, and I can tell you that it works. I could also buy a commercially available pump and just install it without caring about how or why it works. That's not my interest though.
Said that, I have no doubt that the Westinghouse pump works reliably. That's out of the question. I have also posted that I don't think the simple over-centre spring arranged pumps will work, not without some modifications. But I am still interested on them because I think it's potentially a simpler design, specially if you replace the burden of the sprung connected rod by suitably placed magnets on the trip rod, leading to a much cleaner design.
As said, I know very little, so I would appreciate any further elaboration on what are the problems people find with over-centre spring pumps, and whether they incorporate some of the enhancements proposed here.
Thanks.
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Post by suctionhose on Sept 4, 2016 20:45:48 GMT
No problem Joan. I'm not upset. I just get bored with reinventing ideas that never were ideal.
Fully respect your enjoyment of alternative thinking.
See what you can find on the Moore Pump. I'll try to get a drawing up when I have time this week.
The Moore is very simple. I restored a real one at one time. I made the innards of it myself and worked well.
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jma1009
Elder Statesman
Posts: 5,923
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Post by jma1009 on Sept 4, 2016 22:15:00 GMT
I agree with Ross, no point in re-inventing the wheel.
The LBSC pivoted rocker arm type works very well in miniature, and is about as simple as you can get but offends purists like me as it looks nothing externally like anything used in fullsize in the UK. But if you arent bothered about this, then it is an excellent starting point. The pivoted rocker arm also avoids the need for crossed passageways.
Cheers,
Julian
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Post by suctionhose on Sept 4, 2016 23:39:47 GMT
This the Moore. The steam comes in at top / centre of steam cylinder. It's directed down the appropriate port by the position of the floating piston.
When the pump strokes it carries the floating piston with it until it passes the inlet hole. The floating piston shifts to the other extreme opening a port for steam to be directed to the other end.
Exhaust passes out through the centre of the shaft and exists to the left of the picture.
The one I made was pre internet days and the only information I had was a verbal description from someone's memory. I had found a rusty pump body - but no working parts - under a piece of iron on a farm one day. (It was a sought after component for the Traction Engine I was restoring)
The parts I made for it were slightly different to this drawing. However, once the principle of operation was described to me I knew what I needed to get it working.
This process is in essence what I am suggesting we can do with the Westinghouse - accept there are proven miniatures about and use our time to uncover those secrets.
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jma1009
Elder Statesman
Posts: 5,923
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Post by jma1009 on Sept 4, 2016 23:59:35 GMT
Hi Ross,
Im sorry, you've got me stumped there with the Moore drawing. There must be a second drawing showing the ports and passages on the steam side surely?
Cheers,
Julian
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Post by suctionhose on Sept 5, 2016 0:14:49 GMT
 I've marked the drawing with a Red line for Steam and a Blue line for exhaust. I had to zoom 300% to see the detail. |
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Post by joanlluch on Sept 5, 2016 6:04:01 GMT
Julian, with all my due respect. You tend to make mentions of things, people or designs as if everyone knew about them. This is not always the case. Then you fail to further elaborate on them. You have kept doing this since I met you in the forums. This is not useful at all. You'd better refrain from posting in such a /half/ way or you risk to be regarded as a petulant person. Furthermore, you have never sent me a single piece of information from old ME magazines despite you have told me you will in multiple occasions. Frankly, I don't think that you have a genuine intention to help. I am not going to insist on that because I become quickly fatigued due to my health issues and I rather want peace. Take care.
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Post by joanlluch on Sept 5, 2016 6:10:14 GMT
Hi Ross, thanks for having taken the time for posting this. That's quite an interesting design.
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Post by suctionhose on Sept 5, 2016 10:29:07 GMT
Joan,
I've always thought it would translate well to a miniature although I haven't had the occasion to try (working on other things).
I chased up another lead as well today but the person had no additional information to offer on the Moore.
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Post by masterdrain on Sept 5, 2016 11:16:49 GMT
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Post by suctionhose on Sept 5, 2016 11:52:23 GMT
Thanks Iain. That is another variation Moore produced having a piston type Main Valve - a spool without rings by the look of it (there's a larger drawing amongst web images for Moore Steam Pump) The "starting buttons" ie a means to give the shuttle a kick if required makes you wonder whether stalling was a problem without a solution in 1898. The drawing I posted refers to a later (I think?) design. They were fitted to 14hp Twin Cylinder Buffalo Pitts TE's of which mine was a 1912 "Special Australian Pattern" (which probably mean't bugger all - the boiler was a foot longer). I guess the recurring feature of single cylinder pumps is that a steam driven shuttle valve imparting movement to the Main Valve is essential. Steam ensures the shuttle is either this way or that. The positivity of Movement for the main valve is necessary to prevent stalling mid stroke. |
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Sept 7, 2016 10:17:36 GMT
Ross
My experience with spring driven pumps disagrees with you assertions. End of story.
Ian
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Sept 7, 2016 10:19:46 GMT
As for the Moore pump. I have seen something similar on full size steam pumps on USA locos. There was no immediately discernible valve gear which one would expect from experience with Westinghouse air pumps or Worthington single cylinder pumps.
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Post by suctionhose on Sept 7, 2016 11:29:51 GMT
Hopefully this links to a video of a Sandberg Pump of the Westinghouse pattern on my 5"g 2-8-0. The pump is about 80mm overall height (the video is tilted 90 deg) No external valve gear. Very controllable and positive. Would keep doing that slow stroke for a couple of hours before the displacement lubricator needed refilling. View My Video |
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jma1009
Elder Statesman
Posts: 5,923
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Post by jma1009 on Sept 7, 2016 23:04:17 GMT
Hi Joan,
The weather here was awfull at the weekend with poor light conditions. I have to take digi pics on my digi camera of old ME articles. I do not have a scanner. The fading brown copies of my old ME's require very good light to take a decent pic that can be read and understood.
The rest of the time I have been in work coming home in darkness. I have found artificial light not good for taking digi pics of old ME's.
You will have to be patient and wait for the weather in South Wales to improve, and coincide with my days off.
Cheers,
julian
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Post by joanlluch on Sept 25, 2016 8:32:30 GMT
Hi Joan, The weather here was awfull at the weekend with poor light conditions. I have to take digi pics on my digi camera of old ME articles. I do not have a scanner. The fading brown copies of my old ME's require very good light to take a decent pic that can be read and understood. The rest of the time I have been in work coming home in darkness. I have found artificial light not good for taking digi pics of old ME's. You will have to be patient and wait for the weather in South Wales to improve, and coincide with my days off. Cheers, julian Julian, I wonder if sunlight has improved in Wales, or your willingness to help rather. I'd suggest you to use a mobile phone camera, these devices are truly amazing at taking fantastic pictures in darkness. |
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