Re-gauging Super Simplex

[David WassonParticipant @davidwasson11489]

I am beginning the build of a freelance steam locomotive design by Martin Evans, Super Simplex. I am re-gauging it to run on 4-3/4" track. Two things that will have to be squeezed to fit between the frames are the saddle and the bottom of the fire box. Since the bottom of the fire box and grate will be 1/4" narrower than originally designed, is there a relationship between the grate size and any other part of the boiler or steam system in general?

[David WassonParticipant @davidwasson11489]

[julian atkinsParticipant @julianatkins58923]

hi david,

as Simplex and Super Simplex have large grates in relation to the overall boiler proportions you can safely reduce the width of the firebox.

one tip i would make is to NOT bore out the cylinders to the drawing size but to make the bores less on Super Simplex. the loco is 'over cylindered', a fault also with Simplex. bore the Super Simplex cylinders out to 1.5" dia, no more. fit top feed to the boiler, and you may also want to add proper crown girder stays or crown rod stays instead of the martin evans arrangement of strengthening the inner firebox crown.

cheers,

julian

[David WassonParticipant @davidwasson11489]

Hi Julian,

Okay, this is the kind of information I need to know. I will bore the cylinders to no more than 1-1/2". What are the potential problems with "over cylindered" locomotives? The Simplex was designed for 1-1/2" bores and the Super was to have 1-9/16" bores.

The crown girder stays were increased in width on the Simplex from 7/8" to 1-7/16" width on the Super. Also, three webs have been added between the girders on the Super. Will this be sufficient?

Thanks for the help,

David

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