How does this pump work?

[PaulR]

I saved this image from eBay some time ago but can't figure out how it works, can anyone enlighten me or tell me if the style has a name?

It has inlet and outlet connectors at the bottom in the photo, but also has another connection about halfway up (at the back on the left). The mechanism on the left is similar to the valve control on Stuart Turner and other pumps - does that mean the inlet/outlet are for steam and the mid connection is for water and if so where is the other one? I have a few other photos if that helps.

[uuu]

I wonder if it's a pressure cylinder rather than a pump.  Perhaps pneumatic. The pump part could be another cylinder mounted on the top.

I'm thinking this from the rod on the left, which would seem to trip the valve at the bottom one way at the end of the up stroke and the other at the end of the down.  Very like the way a Stuart (or similar) steam pump works - as you say.  Perhaps the upper union connects in some way  to the valve block at the bottom?

Wilf

[PaulR]

I wonder if it's a pressure cylinder rather than a pump.  Perhaps pneumatic. The pump part could be another cylinder mounted on the top.

I did wonder about the disc at the top but it doesn't appear to have any holes to attach to a cylinder. The rod at top is thinner than the 'pump rod' and it has a rounded end which doesn't seem to attach to anything. Are you thinking it's more likely from an air compressor or to pump small volumes of air for some purpose?

[PaulR]

Forgot so say, if the info I saved at the time is correct it's 22 inches long - quite a size!

[uuu]

This is the kind of thing I was thinking of: <a href="https://www.youtube.com/watch?v=MEnQBf019Sw" target="_blank">http://www.youtube.com/watch?v=MEnQBf019Sw</a>

Wilf

[PaulR]

I found a 'how it works' video but this one doesn't show how air is getting to either end of the cylinder or any sort of valve (and it only seems to exhaust about half the air). Other than that it looks like a regular pump.

<a href="https://www.youtube.com/watch?v=IWLm1yMYxug" target="_blank">http://www.youtube.com/watch?v=IWLm1yMYxug</a>

[PaulR]

Some years ago I made a weedy little thing using that type of valve control, it runs really well but I never added a pump as it doesn't have anywhere near enough oomph! I might just make a bigger version while cogitating on the next engine project.