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Looking for a Front End Throttle
http://www.rypn.org/forums/viewtopic.php?f=1&t=41916
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Author:  hadder [ Mon Apr 23, 2018 4:08 pm ]
Post subject:  Looking for a Front End Throttle

I'm looking for a Front End Throttle Casting, in reasonable shape that can be cleaned up and placed in service. If anyone has any leads, please PM me. Thanks.

Eric Hadder
CMO
Grand Canyon Railway

Author:  Dave [ Mon Apr 23, 2018 5:40 pm ]
Post subject:  Re: Looking for a Front End Throttle

I think it was SteamRanger in Australia that had to cast a new one several years back - you might talk to them about using their patterns to have a new one cast for you.

Author:  whodom [ Mon Apr 23, 2018 6:47 pm ]
Post subject:  Re: Looking for a Front End Throttle

I'm sure this will be an interesting search; hopefully something you can use will turn up.

Won't a front end throttle be somewhat locomotive-specific though? Assuming you mean a multiple valve type incorporated into the superheater header, I'd think the superheater arrangement for the new throttle needs to be relatively close to the existing arrangement in your boiler. Type A or Type E for instance, set up for a minimum number of superheater elements. "Excess" connections for superheaters could be blanked off. The overall width would be another detail that would be important, but as long as the superheater arrangement is similar hopefully it would be too. I imagine almost any throttle could be made to work, but the farther it is from the ideal configuration the more work it will be.

One other point that Dave's post reminded me of- at least some front end throttles used outside of the US had the throttle valves upstream of the superheaters, which would seem to negate much of the system's advantage (ability to use superheated steam for the blower and auxiliaries). Wardale mentions that the SAR 25NC and C 4-8-4's had their throttle valves upstream of the superheater header. It would be a good idea to determine that arrangement before you source one from outside the US.

Author:  SouPac [ Mon Apr 23, 2018 9:02 pm ]
Post subject:  Re: Looking for a Front End Throttle

I don’t have the header but I do have a hanging “grapevine” throttle lever, quadrant, and bell crank if you need it. Let me know.

Author:  whodom [ Tue Apr 24, 2018 12:24 am ]
Post subject:  Re: Looking for a Front End Throttle

Another thought inspired by Dave’s post: David Wardale also mentioned that the SAR used both cast and fabricated superheater/throttle assemblies, at least on the GMAM Garratts. If making your own becomes the only viable route, it’d be worthwhile to consider both methods.

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