A few months ago, we shared our ongoing work on the Great Smoky Mountains Railroad’s Southern No. 722. The iconic steam locomotive is being painstakingly rebuilt with a blend of new and reconditioned parts. Since that time, our team has made progress as the project moves closer to the final stages.
A Recap of Southern No. 722’s History
Built in 1904 by Baldwin, the Southern No. 722 was a 2-8-0 Consolidation steam locomotive. Originally, it hauled freight on the Southern Railway’s Murphy Branch in North Carolina. After its retirement in August 1952, it became an excursion engine until 1985 when its boiler certificate expired. The Great Smoky Mountain Railroad acquired the locomotive in 2000.
What New Work Has Been Done?
At the start of the project, we were tasked with inspecting and repairing the boiler, as well as performing machine work on the drive wheels. We also refurbished and manufactured new drive axle boxes, crown brasses, and cellars for the locomotive.
Since our last update, here’s what the team has accomplished.
The Boiler
Work on the boiler is at the forefront of the restoration. The new firebox crown and side sheets have been test-fitted, with crews creating perfect alignment for the stay bolts. The rear flue sheet has been spot-welded into place on the firebox, and the entire firebox was temporarily placed inside the boiler for alignment checks. The next step will be the final installation of the firebox and the rear flue sheet.
Our team also inspected the rivets and replaced any damaged or old ones. Rivets are heated to a searing 2,100-2,200°F before being hammered into place, replacing the temporary bolts. This process ensures the structural integrity of the boiler.
Before the restoration can be completed, a new rolled steel smokebox will be installed. One of the final tests will be a hydro test, which is used to check for leaks in the boiler courses, any patch work on the boiler, flue sheets, and firebox. This test also checks for interior or exterior leaks around the staybolts. This is part of its Federal Required 1472 Service Day Inspection. The team is also completing a digital UT grid for the necessary Form-4 boiler calculations.
Other Repairs
Beyond the boiler, other crucial components are also being worked on. The locomotive’s crown stay-bolts were recently treated to a process called annealing. By heating the stays to 1,740-1,840°F and then slowly cooling them, the team reduces internal stresses in the metal. This process helps increase their durability and was performed on over 200 crown stays.
The eight driving boxes, which are critical for the locomotive’s wheel assemblies, have been either reconditioned or newly manufactured in-house. All of them have new crown brasses and cellar boxes installed, and they are ready to be reinstalled on the locomotive.
As these complex tasks are completed, the Southern 722 is inching closer to a new life on the rails.
Preserving History One Project at a Time
As you can see, this is a multi-step restoration that is ongoing in our shop. We’re taking our time and not rushing any steps because we’re committed to doing the job right the first time.
We’re passionate about preserving and restoring steam locomotives. Our goal is to save these incredible machines from the damage of time, and we’ll do everything we can to prevent their loss.
Need help with your steam locomotive restoration project? Contact our team to get your project back on track.