Re: K-27s D-Slide Valves Question?
| January 02, 2011 10:59PM |
Oh, the kid asks BIG questions!
Cole, the conversion to superheat is not an easy or simple task. You strip the boiler of all of its flue tubes and the flue sheets. You install new flue sheets with a mix of small and large holes for the normal flue tubes and the large diameter flue tubes into which the superheater elements are inserted. You have to decide whether you are going to continue with a dome throttle or convert to a front-end (smokebox) throttle, you make the appropriate changes in the throttle system and perhaps run a new dry pipe through the front flue sheet. On the hot side of the superheater elements, you have to install new branch pipes through the sides of the smokebox to the cylinders, and since you don't want to have to replace the cylinders and saddle, you plug the old live steam passages, leaving the exhaust passages for continued use. You remove the old "D" (slide) valves, buy a piston valve kit from the locomotive builder or an "appliance" manufacturer like Franklin, and install them in place of the old D valves. If you have a locomotive with Stephenson valve motion lurking inside of the frame, you might want to scrap the Stephenson motion and replace it with some sort of more efficient radial gear like Walschaerts, Baker, or Southern. If everything falls into place, you now have a modernized, superheated steam locomotive. As you can see, it is a time-consuming and expensive task, so you need to have a commitment to using a locomotive for an extended period of time after the conversion. Often these conversions were done when a locomotive was in the shop for a "class" overhaul and would be torn apart anyway. Don't ask me about valve motion, because what I know of valve motion long ago convinced me that they were creations of He Whose Name Shall Not Be Spoken!
Below is a photo of ex-IRCA/ex-Georgetown Loop Baldwin #40, which wears a superheater conversion. #40 retained her dome throttle, so she has a damper plate in the smokebox that operates off the steam coming from the throttle to open when the throttle is opened and to close when the throttle is closed, thus keeping the superheater elements from being burned out by the fire. The problem with dome throttles is that, when they are closed, there is no steam in the superheater elements to "cool" (I use that term loosely) them, hence the damper. With a front-end throttle, there is always steam in the superheater elements. Another problem with dome throttles is that there is always a delay when you open the throttle, as steam must pass from the throttle through the superheater before it can reach the cylinders and do useful work.
Also below are a couple of illustrations that may or may not help you understand superheaters. They were taken from an on-line write-up posted by the San Diego Railroad Museum, with information taken from Locomotive Boilers and Engines, published by the American Technical Society in 1920. There are several varieties of Superheaters; this is a Cole superheater.
The reason for the conversion to piston valves when superheating is that it was found that there were problems keeping the wearing surfaces of the valve components lubricated, resulting in accelerated wear. Lima stubbornly resisted installing piston valves on superheated Shay locomotives, even when the railroad shop guys were clamoring for them. After Willamette Iron and Steel of Portland, OR, introduced its Shay "clones" (when the Shay patents expired), Lima sure got religion real quick and started offering piston valves for installation on Shays.
OK, TMI again. No apologies--Cole needs to learn somewhere.
Other shop rats are invited to comment on, add to, or challenge the foregoing thoughts!
PS. I strongly recommend you acquire for yourself a copy of John H. White, Jr.'s book, A History of the American Locomotive--Its Development: 1830-1880. It won't answer all your questions about modern steam locomotives, but it will give you a firm basis for learning more about steam locomotives. It's available through Amazon. Don't even ask about a new copy ($194.10!!!), but you can buy an used paperback version for $24.95 and up. The price suggests that it is a "must have."
Can't answer your question about #462.
Mike
Edited 1 time(s). Last edit at 01/02/2011 11:02PM by mikerowe.
Cole, the conversion to superheat is not an easy or simple task. You strip the boiler of all of its flue tubes and the flue sheets. You install new flue sheets with a mix of small and large holes for the normal flue tubes and the large diameter flue tubes into which the superheater elements are inserted. You have to decide whether you are going to continue with a dome throttle or convert to a front-end (smokebox) throttle, you make the appropriate changes in the throttle system and perhaps run a new dry pipe through the front flue sheet. On the hot side of the superheater elements, you have to install new branch pipes through the sides of the smokebox to the cylinders, and since you don't want to have to replace the cylinders and saddle, you plug the old live steam passages, leaving the exhaust passages for continued use. You remove the old "D" (slide) valves, buy a piston valve kit from the locomotive builder or an "appliance" manufacturer like Franklin, and install them in place of the old D valves. If you have a locomotive with Stephenson valve motion lurking inside of the frame, you might want to scrap the Stephenson motion and replace it with some sort of more efficient radial gear like Walschaerts, Baker, or Southern. If everything falls into place, you now have a modernized, superheated steam locomotive. As you can see, it is a time-consuming and expensive task, so you need to have a commitment to using a locomotive for an extended period of time after the conversion. Often these conversions were done when a locomotive was in the shop for a "class" overhaul and would be torn apart anyway. Don't ask me about valve motion, because what I know of valve motion long ago convinced me that they were creations of He Whose Name Shall Not Be Spoken!
Below is a photo of ex-IRCA/ex-Georgetown Loop Baldwin #40, which wears a superheater conversion. #40 retained her dome throttle, so she has a damper plate in the smokebox that operates off the steam coming from the throttle to open when the throttle is opened and to close when the throttle is closed, thus keeping the superheater elements from being burned out by the fire. The problem with dome throttles is that, when they are closed, there is no steam in the superheater elements to "cool" (I use that term loosely) them, hence the damper. With a front-end throttle, there is always steam in the superheater elements. Another problem with dome throttles is that there is always a delay when you open the throttle, as steam must pass from the throttle through the superheater before it can reach the cylinders and do useful work.
Also below are a couple of illustrations that may or may not help you understand superheaters. They were taken from an on-line write-up posted by the San Diego Railroad Museum, with information taken from Locomotive Boilers and Engines, published by the American Technical Society in 1920. There are several varieties of Superheaters; this is a Cole superheater.
The reason for the conversion to piston valves when superheating is that it was found that there were problems keeping the wearing surfaces of the valve components lubricated, resulting in accelerated wear. Lima stubbornly resisted installing piston valves on superheated Shay locomotives, even when the railroad shop guys were clamoring for them. After Willamette Iron and Steel of Portland, OR, introduced its Shay "clones" (when the Shay patents expired), Lima sure got religion real quick and started offering piston valves for installation on Shays.
OK, TMI again. No apologies--Cole needs to learn somewhere.
Other shop rats are invited to comment on, add to, or challenge the foregoing thoughts!
PS. I strongly recommend you acquire for yourself a copy of John H. White, Jr.'s book, A History of the American Locomotive--Its Development: 1830-1880. It won't answer all your questions about modern steam locomotives, but it will give you a firm basis for learning more about steam locomotives. It's available through Amazon. Don't even ask about a new copy ($194.10!!!), but you can buy an used paperback version for $24.95 and up. The price suggests that it is a "must have."
Can't answer your question about #462.
Mike
Edited 1 time(s). Last edit at 01/02/2011 11:02PM by mikerowe.
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488 stops for water at Los Pinos tank on closing day Oct. 1979. Photo courtesy Don Richter
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