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 Post subject: Steam Brake Question
PostPosted: Mon Oct 15, 2018 5:01 pm 
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Joined: Mon Jan 09, 2006 4:37 pm
Posts: 56
Sounds crazy but, I'd like to put brakes on a locomotive that will likely never run.

About a year ago, I acquired a 36 inch gauge 0-6-0 locomotive, built in 1890 by H. K. Porter as a street motor or steam dummy, CN 1167.

It originally had steam brakes but, the cylinder is missing.

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File comment: Original Brake Rigging
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The cylinder is very similar to that on CN 922 shown below.
I regret not closely examining the feature circled in red below, when I had the chance.
However, based on the Porter drawings, it appears to be just a support.

Anyway, the cylinder seems simple enough to replicate.

CN 922 has a single steam line connection and small vent hole in the cylinder head.
There was no return spring so, any pressure was released either at the brake valve or through a cylinder drip valve, when the steam was cut off.

Does my theory about the support and steam connections make sense?

I'd like to hear about any similar setups.

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File comment: CN 922 Cylinder
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File comment: CN 922 Cylinder
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File comment: Porter Drawing
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File comment: Porter Drawing
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File comment: Porter Drawing
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Thanks,
Dave


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 Post subject: Re: Steam Brake Question
PostPosted: Mon Oct 15, 2018 6:26 pm 

Joined: Tue Sep 14, 2004 7:52 am
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Location: Strasburg, PA
I believe that steam brakes use double acting cylinders. If not, there wouldn't be any reason to have a packing gland on the piston rod. I expect that the circled feature in your photo is the steam inlet to the piston rod end of the cylinder.

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 Post subject: Re: Steam Brake Question
PostPosted: Mon Oct 15, 2018 6:57 pm 

Joined: Sun Aug 22, 2004 7:19 am
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Location: southeastern USA
I've worked on some small lokies with steam jams - the majority do not have the steam pipe on the end with the packing gland - in fact, don't have a packing gland at all, because the steam goes in and out of the other end. Some don't even have a head on the steam side.... anyhow, what's important in your pictures is the slope down from the bore to the steam line in / out. At the lowest point is the condensation relief valve which is a poppet valve like a snifter but held up from its seat by a spring with very little spring rate on it. Steam entering the line to the cylinder close it against it's seat. Steam having been removed by means of the 3 way steam brake valve in the cab the lack of pressure in the cylinder / line allows the spring to lift it off its seat and gravity drains the condensation - vacuum is broken through the valve being open to the exhaust / outside air. Somewhere I think I have the Glover Machine Works drawings for this stuff...….

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 Post subject: Re: Steam Brake Question
PostPosted: Mon Oct 15, 2018 11:20 pm 

Joined: Wed Nov 23, 2016 7:05 pm
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Looks to me like the cylinder is in fact a single acting 'pull' type with packing gland. The rigging drawing confirms it's a pull type with the (looks like 5.5" x 5.5") dead lever arrangement on the rear brake beam. Do you have a drawing of the cylinder head? It would tell if there was provision for a spring return, even if 922 didn't have one. An older, small, inexpensive, very-low-tech switch engine might not have much of a return system since banging around would loosen things up fairly quickly and they weren't operating at high speed. The small hole in the head would be the air exhaust for applying the brakes - its small size would function as an orifice to limit the speed the piston can move to avoid hammering the brakes. The boss you circled looks like it's intended to be bored as an oil cup or lubricator line fitting for the piston. Might have been a customer option since there isn't any boring/finishing drawn on the prints. It's a pretty crappy location for a cup, being right in front of the ash pan. A better solution was probably steam oil in the brake steam supply - maybe a small single displacement lubricator if the customer wanted to splurge.

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 Post subject: Re: Steam Brake Question
PostPosted: Tue Oct 16, 2018 8:55 am 

Joined: Tue Sep 14, 2004 7:52 am
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Location: Strasburg, PA
TrainDetainer wrote:
Looks to me like the cylinder is in fact a single acting 'pull' type with packing gland. The rigging drawing confirms it's a pull type.

Right you are, good eye.

Here is the only published information on steam brakes that I could find. Per the plumbing, they are pull to apply as well, but they have "push" rods coming out of the piston rods:

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"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."
C. S. Forester

Strasburg Rail Road Mechanical Department


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 Post subject: Re: Steam Brake Question
PostPosted: Tue Oct 16, 2018 11:26 am 

Joined: Thu Sep 22, 2011 4:29 pm
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Location: Youngstown, OH
The Lima brakes were double acting, in that they had a steam back-off feature. When a Lima brake is released there is a very audible clunk as the brake fully retracts.

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 Post subject: Re: Steam Brake Question
PostPosted: Tue Oct 16, 2018 12:54 pm 

Joined: Sun Aug 22, 2004 7:19 am
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Location: southeastern USA
The release on the little lokies is from the weight of the shoes dropping themselves away from the treads. I think the hole in the head in your picture is to prevent back pressure or vacuum on the "wrong" end of the piston space in the cylinder. The boss at the low corner could be for the steam line or a separate condensation drain valve.

Lima sure did know how to complicate things......

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Corollary: "He who does is doomed to watch those who don't repeat it anyway."


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 Post subject: Re: Steam Brake Question
PostPosted: Tue Oct 16, 2018 4:02 pm 
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Joined: Mon Jan 09, 2006 4:37 pm
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I certainly appreciate the comments.

Here's a slightly different or vertical setup with a drip valve.
I'm guessing this is single action, with piping from head to drain condensate.

Attachment:
File comment: Porter Drip Valve
DSC05444r.jpg
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Thanks,
Dave


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 Post subject: Re: Steam Brake Question
PostPosted: Tue Oct 16, 2018 4:52 pm 

Joined: Wed Nov 23, 2016 7:05 pm
Posts: 131
I've worked on a Davenport that had double acting steam brakes and Kelly has the Lima literature - so another question is was Porter the only one to use single acting?

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 Post subject: Re: Steam Brake Question
PostPosted: Tue Oct 16, 2018 5:13 pm 
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Local museum has a Vulcan locomotive with a single acting steam brake cylinder.
It's about the same size but slightly different configuration. Original piping is missing.

The Porter drawings show many configurations of brake cylinders, including air, vacuum and steam, single and double action.

Thanks,
Dave


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