Axle pump

[JBodenmann]

Here are a couple pics of the axle pump for the 0-6-0. After chatting with my friend Doug Alkire it was decided to build a three cylinder pump for smoother operation, instead of a two cylinder. The main body and cylinders is 932 bronze. The packing caps are aluminum bronze with 7/16-40 threads. I am using poppet valves with O ring seats. I like this set up as opposed to a metallic ball on a metallic seat. I have been making my boiler check valves this way for years and they seem to be less vulnerable to contamination (small junk in the water) than a metallic ball. Still have to make the bottom valve body, and the top bit. The excentric straps will be 932 bronze and the excentrics will be ductile iron. This combination of iron and bronze works really well. It pays to think about things for a while. I have been thinking and scribbling for a bit and was able to simplify the design and eliminate a few parts that I originally thought I needed.

[JBodenmann]

Here is a close up of some of the poppet valves. I just love the small size of the parts when working in 3/4" scale. I have been keeping my frame on the coffee table so I can look and brainstorm with my note pad in the evening. The poppet valves are silicon bronze, nice tough stuff but you must have very sharp tooling. Time to get out in the shop, Too Much Fun!
Jack

[Pennsy fan]

Jack,

Is the 932 the same as ALBronze?
d.

[LivingLegend]

David:

932 is the same as 660 bronze.

LL

[ccvstmr]

Jack, first time I saw your poppet valves...reminded me of the working part in the boiler check valves on my Rutland. Nice work. Let me ask...after silver soldering (I assume)...will you give that the same treatment as your steam turret? ...rounded the corners and face-to-face meeting with the sand blaster so it looks like a casting? Carl B.

[prlawiii]

Jack, where is the outlet from these valves? I had determined to make almost identical valves for the axle pump on my Allen Mogul, but thought that I would have to groove the top of the poppet (shuttle?), to provide a path for the outlet flow. Is there some simpler way?

Thanks,

Herman


Just starting an Allen Mogul

[Bill Shields]

$1.00 says that the outlet is part of the cover plate yet to be attached that will also limit the poppet lift.

It's a beautiful job. I have built quite a few 2 cylinder pumps, but the 3rd seems like a very logical progression to minimize pulsing.

[JBodenmann]

Here are a few more shots of the axle pump. This is the main body upside down. The cavities for the poppet valves are 7/16" diameter and the poppets are 5/16" diameter. The slots in the bottom of the cavity (which is actually the top as it is upside down) will let the water flow around the valve and into the cylinders.

[JBodenmann]

Now you can see the bottom, or inlet valve assembly at the upper left. The main body on the right will flip over onto the inlet valve assembly. The cavity's on the main body will allow the poppets to lift .030".

[JBodenmann]

Here we now have the outlet valve bits. The top for the outlet valves in front, the recesses in it will allow the outlet valves to lift .030" just like the inlet valves.

[JBodenmann]

Here is a good view of the outlet valve cavities and the porting. As the valves are 5/16" diameter and the cavities are 7/16" the water can flow around them through the milled slots and down and out through the hole to the bottom of the valve. I will not drill the water inlet and outlet until I get a bit more of the locomotive built. Murphy's law being what it is, I know if I haul off and drill them now I will get them in the wrong place.

[JBodenmann]

All assembled with it's eensy weensy little pistons. Pistons are 5/16" diameter 300 series stainless. This was a delightful little puzzle, but a bit of a challenge. There just ain't much room to play with.