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Self Guarded Frogs; any ideas
https://fast-tracks.net/forums/viewtopic.php?f=4&t=1152
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Author:  Glen Moffat [ Wed Jan 26, 2011 2:07 pm ]
Post subject:  Self Guarded Frogs; any ideas

Noticed that some prototypes use a self guarded frog and wanted the forum's feedback/recommendations on how best to model this or if in fact it really makes sense to do it.

I am in N guage so this may also colour everyone's answer.

Author:  emccamey [ Wed Jan 26, 2011 5:47 pm ]
Post subject:  Re: Self Guarded Frogs; any ideas

Modeled self guarding frogs are possible ONLY if ALL the wheel sets have the same wheel profile. This can be a big problem, as many scales (and yes especially N scale) have a very wide variety of wheel profiles installed and marketed by the manufacturers. Even so, the use of self guarded frogs would have to obey the prototype practice of very slow speed operation in yards and secondary traffic routes.

N scale has 9 distinctively and widely marked wheel profiles - most would be incompatible with a single common self guarding frog. HO has at least 3 divergent wheel profiles (and even with all NMRA RP-25 code 110 wheels) there are interface problems.

There are some modeled self guarded frogs - but only in the pure PROTO scales specifications where the tolerance on wheel profiles is very tight. These are small display modules and obey very careful attention to trackwork, speeds, and equipment.

Possible yes - practical; not likely for most modelers.

-ed-

Author:  Glen Moffat [ Wed Jan 26, 2011 6:08 pm ]
Post subject:  Re: Self Guarded Frogs; any ideas

thank you for the reply and very informative response.

I now completely understand why I will go forward without this specific detail in place :D

I look forward to continuing this adventure

Author:  P Bender [ Thu Jan 27, 2011 12:42 pm ]
Post subject:  Re: Self Guarded Frogs; any ideas

Can somebody supply me with a picture of a self guarding frog (and what it is supposed to do)

I do not know what they are, being Dutch / Continental. Sounds like something typical for US practice

Author:  emccamey [ Fri Jan 28, 2011 11:02 am ]
Post subject:  Re: Self Guarded Frogs; any ideas

The self guarded frog has lip edges that raise up and contact the face of he wheel and guide the wheel flange properly. There is no guard (or for continental - check) rails.

-ed-

Attachments:
self_guard_frog.jpg
self_guard_frog.jpg [ 10.7 KiB | Viewed 10929 times ]

Author:  P Bender [ Fri Jan 28, 2011 2:24 pm ]
Post subject:  Re: Self Guarded Frogs; any ideas


Author:  emccamey [ Fri Jan 28, 2011 5:39 pm ]
Post subject:  Re: Self Guarded Frogs; any ideas

Cheaper (no guard rail and reduced turnout maintenance), relies on only wheel width for checking, the wheel check gauge can be worn or out of specification, and reliable (but slow speed operation is necessary).

-ed-

Author:  paultup [ Wed May 09, 2012 10:26 am ]
Post subject:  Re: Self Guarded Frogs; any ideas

Not sure if you all caught this:

http://www.proto87.com/new-products.html

Self-guarded frogs coming soon! I assume you'll be able to build up the Fast Tracks turnout, but leave the frog out, and then splice in their frog casting. I'll have to test it when they come out...

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