Brass for cylinders

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Brass for cylinders

This topic has 7 replies, 6 voices, and was last updated 14 November 2016 at 13:58 by Phil H1.

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13 November 2016 at 20:25 #266425
Phil H1
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@philh196021
Does anybody have any experience with the use of drawn brass bar for the fabrication of 3 1/2" gauge locomotive cylinders? I can understand the need to exclude brass from a boiler but is it any use for cylinders (with the correct piston material and the use of 'o' rings etc)?.

Phil H
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13 November 2016 at 20:25 #8387
Phil H1
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@philh196021
13 November 2016 at 20:46 #266427
Another JohnS
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@anotherjohns
Phil;

Kozo Hiraoka's "Building the New Shay" specifies brass, with "O" rings on pistons. His previous books specified copper-tin bronze, with graphite packing.

The Gauge 1 builders (e.g. "Project" design) use brass for the cylinder(s).

I've no direct experience, but others design this way – I'd assume it would be ok.

John.
13 November 2016 at 23:34 #266445
julian atkins
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@julianatkins58923
The problem with fabrication if silver soldering the parts together is that the brass will be soft. It can be age hardened. I dont know of a quicker process. I remember LBSC stating even phos bronze/gunmetal should not be silver soldered for cylinder and valve parts as it significantly affects the wearing properties. Whether this is correct or not I dont know myself.

Generally one should avoid brass in cylinder parts as it wears badly anyway compared to gunmetal castings or bronze.

If you are building a 3.5"g loco it would be a shame to spoil it by not using the correct materials for the job.

Cheers,

Julian
14 November 2016 at 05:36 #266454
michael howarth 1
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@michaelhowarth1
I am a Gauge 1 type and invariably use brass for cylinders, but, at this small scale "O" rings are usually used as piston rings so that there is little or no wear in the cylinder walls. Whether this is possible in larger scales I have no idea but I would tend to take the advice given by Julian if I were investing the time, effort and expense in building a 31/2" loco.

Mick
14 November 2016 at 06:24 #266455
MW
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@mw27036
Posted by julian atkins on 13/11/2016 23:34:10:

If you are building a 3.5"g loco it would be a shame to spoil it by not using the correct materials for the job.

Cheers,

Julian

Agreed, it's disappointing to be told to need to change things; it's better to try again for the sake of a better outcome and at least one now knows more than one did the first time around.

Michael W

Edited By Michael Walters on 14/11/2016 06:25:30
14 November 2016 at 10:25 #266492
Ian S C
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@iansc
If the cylinders were to have liners, softening by heating would not be a problem, although you might want to put something harder on the valve face, but I can't see a difficulty there.

Ian S C
14 November 2016 at 13:58 #266553
Phil H1
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@philh196021
Thanks for the answers chaps. Perhaps I should have been more specific because my main concern was not the wear. My main concern was how the material behaves in contact with superheated steam followed by wet soggy steam, water and oil etc

One of the reasons for asking is that I notice many of the steam and water valves that you can buy definitely specify a brass body rather than bronze or gunmetal. Again I understand that valves can be replaced but what happens to the brass bodies and seats? Do they basically corrode and fail or start passing within a relatively short service time? Does brass just go orrible but gunmetal remains relatively clean and unharmed?

PhilH
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