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    Here is an idea for producing easily convertible dual gauge drivers and wheels.  This will work as long as the only difference between the gauges is the actual gauge.  All other standards should be the same (ie. Flange depth, flange radius, etc.).  This suggestion was presented and discussed on the Live Steam E-Mail forum.  Frank Hoppe originally came up with this idea.  This idea can be applied to the troublesome 7 1/2" or 7 1/4" and 4 3/4" or 5" gauge problems.

    The idea is that the wheels and drivers are equipped with adjustable tires.  The hubs and tires are threaded for either 8 tpi or 16 tpi threads and the tires are screwed in or out to adjust the equipment gauge.  A setscrew whose hole is drilled and threaded at the tire hub boundary is used to secure the assembly at the proper gauge (see Figure 1).   To adjust the gauge the setscrew is removed,  the tire is rotated either one turn for 8 tpi or two for 16 tpi, and the setscrew is reinstalled.  This gives an 1/8" change to each side for a total change of 1/4".

    For new equipment some considerations should be taken into account.  The frame and journal blocks must be made so that the tires can be set to the narrower gauge without interference.  This mainly involves building the frame to the 7 1/4" or 4 3/4" standard.  The cylinders, rods, and truck frames (for pilot/trailing trucks, rolling stock, or diesel engines) must be built to the 7 1/2" or 5" standard to allow the tires to be adjusted out.  The hubs themselves can be set to either standard.  I recommend building them to the gauge that you will must frequently be running on.  By doing this the tires will be fully engaged at most times, providing for a stronger joint and also protecting the threads from dirt, dings, and other hazards.   For 7 1/4" this means that the hub is set at 7 1/4" and the crankpins are extended an extra 1/8" to line up with the cylinders and connecting rods built to the 7 1/2" standard.  In any case, anti-seize or other compound should be used on the threads to protect them from rust and (of course) seizing.

    Modifying existing locomotives, diesels, or rolling stock can range from simple to impossible, but the challenge is part of the fun isn't it?

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