When I saw my first Shay locomotive it was a 1:20.3 model, I was intrigued by its eccentric offset boiler but to my eye it looked all wrong. Back in 2001, I rode my first full-sized Shay at the Roaring Camp and Big Tree's Railroad located in Felton, California. The first thing that amazed me was the torque of the loco. I have experienced the power of a dog sled team and also that of just a couple of horses in tandem. The Shay was no different in that it went from a stand-still to its cruising speed in an instant. Infinite acceleration. A low top speed, but I was hooked.

As I investigated the Shay a little more I realised that it had great scalability as it could be built with 2 or 3 cylinders and 2 or 3 trucks, way better than say the Climax. It was also very easy to re-gauge as there was no need to quarter the drivers. It also became to be known that it could easily negotiate rough track with ease as found on many logging railroads. Wow!

On to the model. The photo above shows the Bachmann Two truck On30 Shay sitting on a short length of HO-scale track. It's a great model but its gauge is wrong for what I need. The two trucks are what we're about to re-gauge. The current gauge of the stock trucks is just a little over 31" (full size). What I'm about to describe is how we can convert this to 3' or 36" gauge. In terms of this project, the gauge will have to move out 5" or 0.100" in terms of the O-scale model.

Please keep the 0.100" measurement in mind because we're going to space the geared side frame out 0.040" and the other 0.060" making a total of 0.100". We're also going to add 0.100" to the driver axles.

At this point, please locate the extremely useful exploded diagrams that came with the locomotive as I will be referring to them as we progress.

Using the box the locomotive was delivered in, line it with a soft cloth and turn the locomotive upside down in the box. The soft cloth will reduce the chances of damaging the locomotive. Locate the bolster cross head screws (part number 10297 on the Bachmann exploded diagram) and using a small cross headed screw driver remove the trucks.

Now, let's take a look at one of the trucks. Identify the bolster at the center of the truck, the driving wheels, the side frames and the brake beams at the ends of the truck. Note the spring wire electrical pickups. Note that some of the parts are made from plastic and others, metal. It's a good idea to use a digital camera or a smart phone and photograph the trucks before they are taken apart. This will be of great help when you come to reassemble them.

Using a small flat bladed screw driver, remove the side frame plastic covers on both sides of the truck (part numbers 00P01 and 00P02). The covers are glued on with a fairly weak glue. I'd recommend working on one truck at a time and storing the parts that are removed in another small box. This will help prevent losing these small, valuable parts. Now to disassemble the truck it will be necessary to break the glue joints that hold the brake beams to the side frames. Remember, the side frames are cast metal while the brake beams are fragile plastic. If you're not sure about this, I'd recommend stopping here. Otherwise, be careful here and avoid breaking the plastic brake beams themselves. Next, unscrew the newly revealed screws that hold the side frames in place on the bolster (part number 10213). Note, the screws on top of the bolster (part number 10033), these should be backed off only a fraction of a turn and not removed. Ensure the spring wire electrical pickups remain aligned.

Remove the driving wheel sets from the truck. Disassemble the driving axle assemblies by gently twisting the driving wheels apart. In doing so, this will reveal a small plastic isolation part so put this aside. Leave the crown wheel beveled gears in place on the driving wheels.

In order to remove the geared side frame from the bolster, it will be necessary to push the upper hooked tab of the gear shaft lid from the inside of the geared side frame toward the outside of the truck. Do this at an approximate 45 degree angle - refer to the drawings and study the plastic hooks on part number 00N01 to see the reason for the 45 degree angle. Remove the gear shaft lid (part number 00N01) from the side frame. Set the drive shaft aside and unscrew the geared side frame.

Click here to see part 2.