You really start to realize how many parts make up a locomotive when you are making each one by hand. You also realize that one small mistake can mean starting all over to build a replacement part. So, they measure, measure again, check their measurements, and then have another workman re-check their work again.
The engine frame is the foundation that everything else depends upon to be straight and square. Here we see 1¼ inch thick steel plate being shaped by a cutting torch.
Next, the frame rails have to be heated and straightened until they are perfectly flat. See the big clamps holding everything in place?
It takes two identical pieces to make up the left and right sides of the engine frame, and the only way to get them exactly the same shape and size is to clamp them together and make all the finishing cuts and surfaces on both rails at once. It takes a big milling machine to do that!
This is an example of turning the wheels in a big lathe to make them exactly round, and also exactly the correct size.
Once the wheel (the inside part) is finished, the tire is put on the lathe and the inside of the tire is cut until it is just 8 one-thousandths of an inch smaller than the wheel. Why smaller?
The tire is heated with a “ring of fire” as you see in this picture, and heat makes it expand. You can see the wheel ready for the tire.
Then the workman, with very special gloves and tools, puts the hot tire over the wheel, where it cools and shrinks into its place, so it won’t get loose or come off.
One other very interesting operation is squeezing the axles into their wheels. The axle is finished to be just five-thousandths of an inch too big to go into the hole in the wheel. This is about the thickness of a human hair. Instead of heating the heavy wheels though, this time we use a very large hydraulic press to force the axle into the smaller hole on the wheel. It takes more than 70,000 pounds of pressure to squeeze the axle into the hole. That’s about as much as a fully loaded semi-truck!
Here we can see the wheels, bearings, and axle after they’re all pressed together, ready to be assembled to the frame.
Next we see the very beginning of the assembly of the tender frame and undercarriage. The tenders of the full sized Mason locomotives were made with oak timbers and strap iron, so that’s how this frame is made too. Next, the axle assemblies are added, then the equalizing springs that are the “suspension”.
There are many, many metal parts that need to be finished to their exact size according to the blueprints. This is a very important step, especially for the “running gear”: the valves, rods, slides, and other parts that move in order to make the locomotive run. The parts are assembled, sometimes several times, to be sure they fit exactly, before they are taken apart and powder coated, painted, or otherwise finished.
In another part of the shop the boiler shell is being built. Even though this engine won’t be powered by steam, the boiler still must look right, and that includes all the other parts that still must work — the smokestack, the bell, the sand dome, and other appliances.
It’s a striking change from the paint marks on raw steel to what we see here! Now it’s starting to look like the locomotives we all recognize from books and videos.
The distinctive “cow catcher” in the front of the engine is being built in a different part of the shop. You can see it here, while the workmen are checking to be sure of the fit. Yes, a cow catcher was an important safety device back in the early days of railroading, because a collision between and train and a cow could derail the train, possibly hurting many people. In the mountains, the cow catcher would also help to bump stray rocks off the tracks too.
It won’t be long now before we’re ready for testing the engine to be sure everything is perfect before we start final assembly.