The steam fountain on this 1922 Baldwin steam locomotive is a cast steel manifold that distributes steam to accessories and appliances such as the air compressor and injectors. It is located on top of the locomotive boiler inside the cab. It is the main fixture for the distribution of steam to all of the appliances except the lubricator. (The lubricator has its own dedicated steam source.) The fountain gets its supply of steam through a pipe that runs all the way into the steam dome. The Turret Valve is the main “stop valve” that is used to shut off all of the steam flowing into the fountain in case of a steam leak or failure. Early locomotives do not have this valve.
All of the valves on the fountain are typically closed or open. The valves include – two injector valves for the Monitor lifting injectors, an air compressor valve, the dynamo valve, the steam heat valve and a valve that supplies steam to the fireman’s manifold. The air compressor valve was made by The Westinghouse Air Brake Company; the injector valves, firing manifold valve and lubricator supply valves are original valves made by the Baldwin Locomotive Works and have been on this locomotive since 1922. This 95-year-old locomotive is amazingly original.
The image above shows the fountain when it was removed from No. 28 last year. The original firing manifold valve was removed in 1992 when it failed and was replaced with a contemporary Lunkenheimer steam valve. It is quite common with historic locomotives that are operating to make field modifications that keep the engine running but may not be historically accurate. Twenty five years ago, the worn valve was put away in the parts warehouse in the valve bin. This valve was located and was rehabilitated by volunteer machinist Robert Williams. It will be put back in its historically correct location getting the No. 28 that much closer to how it would have looked back in the 1920s.
The type of valve that best describes the ones used on the fountain is the globe valve, seen below.
The valve stem or spindle (E) is located in the center. It is the bronze rod with the red handle on it. The stem is held in place by the valve body (G) and the bonnet(C). The bonnet also holds the packing nut (F) in place over the stem. This packing nut along with the packing bushing hidden underneath the packing nut (F) (not shown in this image) keeps the steam from escaping up the stem. When the packing nut is tightened, pressure is applied evenly to the top of the packing bushing which then compresses the packing on the stem creating a steam tight seal. The union nut (B) holds the bonnet in place. The threads on the valve stem allow the sealing disc (D) to travel into the seat (A) or away from the seat (valve in the open position) when the handle is turned. This diagram shows the valve in the open position. A top nut (H) secures the handle to the stem/spindle.
The work on the valves at the fountain is extremely specialized; as with most parts on a steam locomotive, there are no part numbers and no technical support.
All of the fountain valves needed attention. Most stems/spindles were completely worn out allowing a lot of play- some almost to the point of thread failure. We ordered C464 bronze stock and volunteer Robert Williams fashioned completely new valve stems for these two valves. Since the stems were very worn, and the internal threads in the bonnet were somewhat less so, Robert used reverse engineering (and some guesswork) to sneak up on the exact dimension and make a perfect fit between the internal threads of the bonnets and the new spindles.
The two identical appearing injector valves gave us a big surprise when it was discovered that one is a 6 pitch (threads per inch) Acme thread and the other is a 5 pitch. We are still wondering if they came from Baldwin that way. For more information on Acme threads click here. https://en.wikipedia.org/wiki/Trapezoidal_thread_forms
All of the packing bushings in these globe valves were found to be in poor condition so all new packing bushings were made to fit the needs of each valve. At the request of George, Robert included a custom lip on the top of each new packing bushing which will make servicing the packing in the future much easier.
The nuts that secure the handles to the top of the stem/spindle, was also of dubious quality with no common design between any of them. It was easier to start fresh with stainless steel hex stock and make tall heavy style hex nuts that will complement the entire set of rebuilt valves and look great for the next century. A custom “washer cut” was made on the nuts while in the lathe so the bottom of each nut will never need a flat washer in service.
The turret valve had a much-corroded seat. Our gracious volunteer machinist used a 3 ½ “valve seat cutter to recut the turret valve seat to perfection, removing almost a century of pit corrosion that looked like Swiss cheese.