RGS #20 Update

We have been working steadily on #20 throughout December and into this month. Erich Armpriester has completed refurbishing the shoe and wedge faces of the frame. Chris Zahrt has been measuring wheels, axles, and valve gear in preparation for making the two new driving axles. Linn finished assembling the frame components and installing the 1-2 equalizers, along with making two new header valve bodies for the injector steam supply. Paul Deevy finished most of the radial and crown stays - which I think I reported previously.

The Colorado Railroad Museum is ramping up the fund drive so we can complete the restoration of #20. We are currently in a state of work where much will be done with little graphic evidence of it. Lots of measuring and re-measuring, some machining and assembly but not a lot of big stuff appearing on the locomotive. The next major assembly sequence will be installation of the driving wheels after all the shoes, wedges, boxes, eccentrics, and tire work is complete.

Here are a few photos showing progress.


This is a view of the valve gear links and link blocks. Note that one in the rear has bushings for the small end of the eccentric rods and the other does not. The one with the bushings has a crack in the block wear face on the back arc. This will be replaced. These links are case hardened steel. They are hardened over their entire surface including the eccentric rod pin holes. The hardening appears to go about 0.020" to 0.040", determined by less hardness detected in the area where the eccentric rods wore laterally into the links. The new rear link arc will be made the same way. It will either be EDM cut or water jet cut with final CNC machining prior to case hardening. After hardening and assembly, the link arc wear faces will be ground to the proper radius to receive the link block.Shims are present to space out the link arcs. This allows for future adjustment as the faces of the block and the links wear. We have yet to determine if we can re-use the old link blocks. If the case appears deep enough, we will grind the blocks to match the link arc and assemble the link with very little (shoot for 0.005") clearance.


The eccentrics shown here and the eccentric straps which ride on these pieces have been measured and we determined that we need to replace the eccentrics due to wear. The combined lateral and radial wear is such that truing up the eccentrics would result in too much material being machined out of the eccentric straps. The eccentrics will be less expensive to replace than the straps and minimal machining will be needed on the straps with new eccentrics.


Prior to designing the axles for #1 and #2 drivers, all the wheels have been bored and the hub faces (down and not shown in photo) machined. This setup is to see where the axle keyway is in relation to the centerline running through the axle and crankpin. Ideally this should be centered on that line and should be oriented radially to the axle center. This is not the case on two wheels, so the keyways will be re-machined. Radial orientation is probably more critical than being centered on the centerline since a step, or offset key can be made. If the orientation is off, the radial planes of the key are no longer parallel, making fabrication more difficult.


Here is an overview of the other drivers.


Here we see Erich's handiwork on the frame pedestals. On the new portions of frame only grinding and surfacing was required to give good bearing for the shoes and wedges. On the old sections of frame, worn areas needed to be built up with weld and ground and polished to be straight, perpendicular, and parallel. The shoes and wedges will have their frame-mating surfaces machined and then they will be put in place on the frame. Once in place the outer faces will be measured and machined to give the desired axle center and proper lateral.


Here we see the main steam header with the new injector steam supply valves attached. The original valves (shown in the background) were installed with the pipe connection facing up. We believe the valves probably had water in them that could not drain out. This water froze and cracked the valve bodies. These are really neat valves and you can't buy new ones, so I made new valve bodies to replicate the originals. They will have stainless steel discs and teflon seats.