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Twins!!!
Shoulda Used Protection !*?%& After getting the bugs worked out of the first pump, I had an extra set of pump castings that were no longer needed and were put up for sale. Instead of selling just one of the castings, I ended up selling both. Now there was a vacancy where the second Westinghouse pump was located. Well, that kinda forced the issue to build a second air pump. Could never have too much air for the brakes on my rig. Before any chips were made, I had to figure out how to avoid all the issue I had building the first one. The biggest issue was keeping the alignment when making the center section. The process used wasn't precise enough to keep things aligned. Finally came up with something that worked out pretty good. After all was done, the pump ran great the first time it was assembled. Need I say I was pleasantly surprised. It took me a fraction of the time to get the second pump machined and operational. All that was left to do was to disassemble, paint, reassemble and install on the Daylight. For those of you interested in how I machined the second pump, my disclaimer is this. I'm sure there are many ways to do this. For what I had at hand and my abilities to get things done, this is what I came up with...
The eight 1/8" brass flanges for the pump were cut to approximate size, stacked, clamped on top of a 1/2" aluminum base and placed in the mill's vice. Two holes were drilled for the dowel pins (as indicated in the photo). The location for the dowel pins (2) were place in an area behind the pump so they wouldn't be visible when assembled. Once the dowel pins were installed, all the holes were drilled as required. Four of the holes were drilled/tapped for 3-48 screws used to hold the flanges together while machining. The dowel pins were used to keep things aligned instead of relying on the alignment washers that were used in the first pump. The alignment washers worked great for the individual air and steam portions of the pump, but when the center section was added, the misalignment was pronounced and difficult (but not impossible) to resolve.
After the holes were drilled in the 8 flanges, four flanges were taken off (top, bottom and 2 centers) and the remaining four flanges were bored to fit the cylinders. Here you can see the dowel pins used to hold everything in alignment. These pins were used throughout the build and to aid in assembly.
Once all the flanges were made, the subsections (steam head, steam cylinders, center section, air cylinders, air head) were soldered together and the mating surfaces machined flat as in the previous build. The steam and air cylinder ID's were roughed-in for final machining to size later.
The subsections were assembled together (using the dowel pins) and mounted on the aluminum base used previously (see below). The entire assembly was positioned so the reversing valve center was set to 0,0 on the DRO. All dimensions were taken from that base location. To insure all the subsections would be aligned, machining would start at the top and work its way down. Luckily, the mill had enough vertical travel to fit the assembled pump without having to re-align anything. Below is a summary of steps taken with pictures to follow.
All the assembled subsections were pinned and screwed together and placed in the mill. The top steam head was then machined for the reversing valve and rod. When done, it was removed from the stack.
The steam cylinders were then machined to final diameters. A 1/8" piece of sacrificial aluminum was placed under the steam cylinders so the center section would not be touched by the boring process. After machining, the steam cylinders and aluminum plate were then taken off the stack.
The center section was next. This was the piece that caused the most problems with alignment on the first pump. As mentioned, none of the piston rod holes were drilled before assembling the center section and were done at this time instead. This made absolutely sure all holes were aligned. When done, the center section was taken off.
The air cylinders were next. Final boring was done. The aluminum block at the bottom server the same sacrificial purpose as the 1/8" aluminum plate when boring the steam cylinders. That is, to allow the boring bar to extend past the cylinders for a clean bore.
After all the subsections were completed, the gaskets were made and the unit was assembled using the alignment pins for each section . When it was time to test the pump, I was totally surprised as the pump ran near perfect the first time. A little adjusting of the reversing valve was all that was needed. What a relief knowing I didn't have to disassemble/assemble the thing a half dozen times to get it running properly. I did have to disassemble it one time for painting. Here's a picture of them installed on the Daylight.
Here's a video if you want to see them working.
So... after a couple years of using these pumps, here are some of my observances. - They do use up steam (Doh!). Actually, I was surprised that it took more work to keep a full head of steam while running both of them. - Keep the steam and air cylinders lubricated. If you don't, they may stall. - Tons of parts on the pump, lines, valves, etc. where leaks can occur. Fix all of them. - The o-rings (Viton) used to seal the check valve caps kept breaking. I think it was a combination of the heat (pump mounted to boiler) and insufficient design to retain the o-ring from popping out. The leaks were temporarily fixed by using thread sealant on the caps. - Polyurethane tubing was used for the air lines with sections using copper tubing to protect it from the heat of the boiler. A leak developed where the Poly touched the mounting bracket and melted. A lot of heat is transferred from the boiler to these pumps which are mounted directly on the boiler. (again Doh!) - Not too impressed with the efficiency of the air pumps. They do work and they do pump up to +100psi but the volume is lower than I would like. I still use my electric pump while I have these pumps running. But... they do start and run reliably without any problems and they sound and look great!
What I would change... - Make the air passages larger. - Find an alternative for the 6 check valves. I think they may be restricting the air flow too much. - Eliminate the use
of the alignment washers. These aren't needed anymore since I now use
dowel pins for alignment. Will have to
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