Pistons and Cross Heads

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It has been a while since I updated this blog, but I have been hard at work on my live steam projects. I have two steam engines in operating condition at my club – Finger Lakes Live Steamers – in Western upstate New York. Of course there is an old joke stating “steam engines are always broken.” Mine are no exception even though they are currently running well. I replaced the whistle valve on my Shay, but the brakes do not work at all! The “500” is sporting new handrails, and even though the steam brakes do work, some of the brake fittings in the cab are leaking steam.

Speaking of the “500,” I hope you all saw it featured on the cover of the May/June 2021 issue of Live Steam And Outdoor Railroading magazine. They did a really nice job of publishing my article.

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The piston rods are half inch 300 series stainless steel. It is very important to make the pistons concentric to the piston rod, so I assembled the piston blank to the rod and then turned the final dimensions as a unit. My six jaw chuck can be adjusted for runout, so I took extra time to indicate it in as close to zero as I could make it.

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The iron rings were purchased from Allegheny York LLC in Manchester, PA. The ends overlap and they are very reasonably priced.

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I honed the cylinders with a brake hone in the drill press before installing the pistons.

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The cross heads are bronze castings from Allen Models. Milling should be straight forward but, I managed to screw things up a bit. The cross hole for the wrist pin was not bored on the center line of one casting, so I had to silver braze a bushing and re-bore it. I also did not get the slots for the guide bars central to the center line for the piston and wrist pin. That means there is an extra step of adding shims between the guide bars and the cylinder mounts at assembly.

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The next step in this project is to get the cylinder assemblies mounted on the frame, so I can make the piston valves and attach the valve gear and rods.