Model Engine Maker
Supporting => Engine Ancillaries => Topic started by: Gas_mantle on February 04, 2019, 08:15:17 AM
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Hi,
I've nearly completed a vertical engine similar to a Stuart no4 and now thinking of make a small boiler feedpump for it to power and be permanently coupled to.
Can any one point me in the direction of some plans to make something relatively simple but reliable in use? I kinda thought about an eccentric driven piston pump similar to those sometimes seen on Stuart no9 engines but open to suggestions.
Thanks :)
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Almost every steam engine designed for work has one as part of the drawings.
The basic design is nothing more than a driven ram and a couple of one way valves - like the little one on Borderer.
Jo
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Thanks Jo :)
Ideally I was on the lookout from some basic plans that have dimensions so I could see what size the valve holes are and the stroke is compared to the bore. I think I could probably make one from guesswork but it would be useful to look at a proven design.
To be honest I'm not certain what size pump I need to keep my 5" boiler fed, I have a 3/8ths ram hand pump that I no longer use and I know from experience that hand operated it is inadequate but may suffice if it was constantly running to keep the water level static.
It may be worth rigging the hand pump up to a temporary eccentric on my engine output shaft to see what its realistic delivery rate is.
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You could base the size on the No9 pump which is 5/16" bore x 5/16" stroke or 8mm x 8mm if you prefer.
Harris's book "Model Stationary and Marine Engines" has a basic design that can be built to suit those sizes.
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Thanks Jason, that kinda sounds a bit small but but I guess Stuart must have made the pump of a size capable of feeding a boiler appropriate to the engine. Really I think I need to experiment with the size by trying the hand ram I have.
It's all unknown territory to me at the moment - do you think a Stuart 10 would be capable of supplying enough water for a 5" dia boiler if its sole job was pumping water ?
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Steam and therefore water usage really depends at the rate you are using it at which will depend on speed and capacity of engine and whether it is under load or just running for fun.
It would probably be better to make a small steam pump with similar bore than to make a 10 and have that drive a separate pump.
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Thanks, I guess the obvious thing is to try and make the 6" Southworth pump but at the moment I think that is beyond my skill. I have the castings for the 3" pump that I want to use on a smaller boiler but don't want to start it till I think I can build it properly.
Ultimately what I'm trying to do is have my boiler as a general use utility item with its own water tank and feedpump permanently fixed but use as little steam as I can in supplying water so that I have enough to run another engine(s).
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Hi
For any boiler, ideally, you should have 3 ways to get water in the boiler, and one of those should be A big juicy hand pump. For small display boilers that are easy to draw the fire I would live with two means of feeding, but always have a reliable hand pump.
Dave
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Hi Dave,
The intention is to have some form of powered feed with a 5/8ths ram hand pump as a back up. At the moment the hand pump can deliver enough water but it's a pain if my engine is revving hard as my boiler is thirsty. :headscratch:
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Yup hand pump is annoying, but if you didnt have one, and wanted practice before you made the steam pump...make the hand pump. ....engine driven is primary is a good plan.
Dave
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Here is a separate pump that can be made from bar stock (one of Elmer’s). You could scale it to meet your needs.
http://www.john-tom.com/ElmersEngines/49_donkeyPump.pdf (http://www.john-tom.com/ElmersEngines/49_donkeyPump.pdf)
Tony
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The axle pump on the Kozo A3 has a 0.4" stroke with a .25" ram, valves are 5/32 balls. Everything is doubled for the 1.5" scale loco with a 6" boiler.
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Thanks guys, that Elmers pump looks reasonably easy to make and is something to consider :)
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Hi Gas_mantle
This might be of some use to you, its a hand pump I built a while back and has been very reliable. I have recently used it to hydraulic test my loco boiler
http://www.modelenginemaker.com/index.php/topic,336.msg2089.html#msg2089
Cheers
Rich
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Thanks Rich that's very useful, it's the kind of thing I'm after and should be fairly easy to convert to power operation :)
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Hi Gas_mantle
This might be of some use to you, its a hand pump I built a while back and has been very reliable. I have recently used it to hydraulic test my loco boiler
http://www.modelenginemaker.com/index.php/topic,336.msg2089.html#msg2089 (http://www.modelenginemaker.com/index.php/topic,336.msg2089.html#msg2089)
Cheers
Rich
Rich, thats a slick setup with the o-rings, had not seen that before, seems like it should hold better than the steel ball method on seats that are not perfect. Interesting!
Chris
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Hi
Yes its a lot easier to get the O rings to seal than balls. It will pump a 100psi no problem and hold without dropping pressure
Cheers
Rich
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the o rings are a great idea!!!!!
I have trouble with the balls sealing, especially after they sit unused for a month or two.
Mike