During the steam era, it took workers with many specialized skills to keep locomotives on the road -- and in fact those locomotives spent much less time on the road per day than their diesel successors: Not only do steam locomotives require much more daily maintenance (oiling, greasing, cleaning the fire, etc.) but their complicated mechanisms required fairly frequent and extensive "backshop" work, taking them out of service for days and even weeks at a time. Project 113 has brought a single locomotive back to life through the application of thousands of hours of labor, much of it on tasks that have largely disappeared in the "real world".
In this sequence of images by, we see the lathe used to grind the top seat of the steam dome. Atop the highest point of the boiler, the steam dome collects the driest steam (farthest from the steam-water interface a few inches higher than the crown sheet). The dome surrounds the throttle valve (top photo), which admits steam to the superheater tubes, from which the now-hotter steam travels to the piston valves and then the cylinders, where the steam does its work to move the locomotive.
Five photos © Vince Labert
With the dome bolted to the top of the boiler, any work on it has to get done in place. Here, two of our volunteers examine the ring lathe that they will lift up onto the dome.
Thirty bolts secure the dome lid. When 200 pounds per square inch of steam push against the lid, each bolt has to withstand more than 3000 pounds of pressure, the lid as a whole more than 100,000 pounds! Around the inner edge of the opening, a metal-on-metal seal keep the steam confined, and the lathe will make a smooth enough surface for that seal to work. The dial indicator at the right helps to get the lathe ring level with respect to the dome. Visible inside the dome, the reinforced opening that will bring steam to the safety valves.
Barely visible inside the boiler, some of the two-inch-diameter tubes that carry hot gases from the firebox through the boiler. In service, water surrounds the tubes, and the heat passes through the tube walls into the water. In the sealed boiler, the water increases in pressure as it heats, and that pressure prevents the water from all turning to steam; many water molecules do boil, making bubbles, and those bubbles rise to the top, just like in the hot water in a pot on the stove. In an open pot, the steam boils off into the atmosphere; put a lid on, and the pressure rises.
The ring lathe actually consists of two rings, one of which turns inside the other. The outer ring gets fixed in place and the inner ring rotates, driven by a compressed-air-driven motor (close to the camera in this photo, with the air hose connected at the top). The cutter, towards the top right in the photo, gets mounted in an adjustable fixture; with each pass, the cutter can get moved down, for a deeper cut, and in and out, to make as wide a flat area as necessary. Between the motor and the cutter we see some of the steel shavings.
With the job mostly completed, we see the shiny steel revealed as the cutter did its work. The dome lid itself will need work to ensure it has an exactly-mating surface, and then of course it has to get lifted into place, and all thirty bolts tightened. The Project 113 crew uses elbow grease by the barrel!
The dome lid offers the only person-sized access to the center section of the boiler as long as the front and rear tube sheets remain in place; we have lost count of how many times our volunteers have climbed in and out!