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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Thu Oct 25, 2018 10:34 am 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 5540
Location: southeastern USA
All are good. I'm unclear as if the locomotive was in motion when the incident happened which could make some difference, so I'm just running a set of mental exercises in the absence of information from people who were there at the time. Most of my work has been on older smaller locomotives with a lot of slide valves, so it's puzzling to me. They're pretty robust, straightforward and forgiving.

Again, just one picture a friend forwarded me which shows some bent and twisted metal valve gear parts but nothing I wouldn't try to heat and straighten in it if it were my situation. No doubt the one picture didn't tell the whole story, the guys on site will make the best decisions about what techniques work best for them in their circumstances. It's simply just easier with today's technology and options to make custom parts than when things were more limited.

Learning, please - we are all stronger when we share experiences and allow each other to steal our good ideas freely, which makes it not stealing at all but - I dare to suggest - collaborate?

I have in the back of my mind an experience I had when a little tank engine with Richardson balanced slide valves but Stephenson gear locked hydraulically due to grunge coming down the drypipe with wet steam at a test run plugging everything up. It didn't cause any damage in my case but we only had about 50 PSI on her at the time...... a warm fog. Unlikely, but.....

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Santayana: "He who does not remember the past is condemned to repeat it."
Corollary: "He who does is doomed to watch those who don't repeat it anyway."


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Thu Oct 25, 2018 2:09 pm 

Joined: Thu Feb 27, 2014 10:08 am
Posts: 406
Thanks, Dave. From the photo you saw, could you tell if the damage shown was on a high pressure engine or a low pressure engine? As noted earlier in the thread, on startup a lot of condensed steam forms in the high pressure system which is then pushed to the low pressure engine when running in compound mode. If the engine was not started in simple mode such that HP steam from the boiler was being directed to the low pressure side until all the engines were warm and condensation ceased, and the cylinder cocks on a low pressure side became obstructed (or were not large enough to allow all the water to escape in a timely manner) such that the low pressure side filled with water, could this have caused the damage you saw in the photo?

With a compound locomotive, on rebuild should the high pressure engines be first blown out with steam before the low pressure engines are reconnected to make sure any welding residue, dust, and grinding dirt that may have been produced during the rebuild is blown out fully and does not get deposited in the low pressure side - and then connect the low pressure side and steam clean the whole thing?


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Thu Oct 25, 2018 2:22 pm 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1467
Location: Strasburg, PA
Scranton Yard wrote:
If the engine was not started in simple mode such that HP steam from the boiler was being directed to the low pressure side until all the engines were warm and condensation ceased, and the cylinder cocks on a low pressure side became obstructed (or were not large enough to allow all the water to escape in a timely manner) such that the low pressure side filled with water, could this have caused the damage you saw in the photo?

Nope. The valve and steam chest see no compression, only the piston in the cylinder. The steam chest can be full of water to the top and it will have no effect, other than washing off the lubricating oil film.

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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Thu Oct 25, 2018 3:03 pm 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 5540
Location: southeastern USA
We do know that either the valve was being forced and the wheels weren't cooperating which seems unlikely in a slide valve, or more likely the wheels were moving until they were stopped by the elements of the valve gear reaching their elastic limit and then some, probably accompanied by expanding verbal expressions....... due to something preventing the valve from being moved. The at least thirdhand report I got was she wasn't moving and this happened when the throttle was opened - but I can't figure out how it could have happened without at least a partial rotation of the wheel.

Outside admission piston valves can act like pistons, however.... but that's another story.

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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: Stretching her legs 63 years later
PostPosted: Thu Oct 25, 2018 3:10 pm 

Joined: Thu Feb 27, 2014 10:08 am
Posts: 406
Thank you, gentlemen. A very interesting puzzle indeed. I have nothing but admiration for the folks at OCSR who put this Humpty Dumpty back together again. I can not imagine how exasperating this last five yards must be for them. Nothing more difficult than rebuilding a machine that was taken apart years ago, often by someone else, especially if the parts were not properly inventoried. A lot of time is spent just correcting past errors and omissions. They got this far and so Im sure they will get into the end zone.


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 1:13 am 

Joined: Fri Mar 23, 2018 12:37 am
Posts: 6
Location: Arroyo Grande, California
This is the photo of skookum. Note, I’m not using it as an attempt to “slander” them. I’m merely calling out that this is NOT a “normal” issue or a simple teething issue.
This photo has been posted on multiple platforms and has made its rounds.

Not trying to get everyone worked up, this way those who aren’t entirely sure can see and make their own conclusions. In my opinion it should be out there and an explanation of what happened to further assist those of us in the steam industry so such does not happen to any other engine.......


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 2:11 am 

Joined: Fri Mar 05, 2010 3:41 am
Posts: 3419
Location: Inwood, W.Va.
Thank you for posting, and doing so without "malice" to the Skookum people.

Yes, it does look like something jammed, and I'm going to guess it was with the valve gear in "compression," possibly when the motion was in about the position it is in now. I'm not an expert, but the damage we can see looks limited to valve gear parts; crankpins and the hanger for the reversing link look OK (though the Skookum crew will have to check those to be certain). There may be other damage further forward we can't see, and of course there's the question of how the jamming occurred in the first place.

It's embarrassing and certainly saddening, but as others have noted, after all that this engine went through, and what the restoration crew has been through, it looks like the repair may be relatively minimal. I can't help but think that stuff like this happened every so often in regular service days; it's certainly less than some other things, like having main and side rods come off at speed, taking the valve gear and running board and anything else in the vicinity off in the process (and tearing up the cab, with the engineer, on a Camelback). There was even a case, in just the past year or so, where a main rod came off Southern Railway (of England) 4-6-2 Tangmere; it hit the third rail, shorting out the power system, throwing circuit breakers and killing operations of other trains for miles around.

Skookum, and her crew, can come out of this.

Let's wish them the best.


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 9:48 am 

Joined: Wed Feb 05, 2014 6:30 am
Posts: 46
J3a-614 wrote:
There was even a case, in just the past year or so, where a main rod came off Southern Railway (of England) 4-6-2 Tangmere; it hit the third rail, shorting out the power system, throwing circuit breakers and killing operations of other trains for miles around.
.

The Tangmere incident was actually in November 2013 - doesn't time fly? The complete RAIB report can be read here (all 45 pages of it!): https://assets.publishing.service.gov.u ... hfield.pdf

In the meantime we should all support the Skookum crew at this difficult time - they must be absolutely 'gutted' after putting all that work in.
Ray.


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 10:27 am 

Joined: Wed Mar 21, 2012 11:29 pm
Posts: 20
Bad things can happen to slide valves if lubrication is lost or not of enough volume. unlike a piston valve all of the pressure in the steam chest is pressing down on the valve; a force the valve gear must over come.


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 12:49 pm 

Joined: Tue Sep 14, 2004 7:52 am
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Location: Strasburg, PA
traindude70 wrote:
Bad things can happen to slide valves if lubrication is lost or not of enough volume. unlike a piston valve all of the pressure in the steam chest is pressing down on the valve; a force the valve gear must over come.

Yes and no. Most 20th century slide valve engines (other than very small ones) have balanced slide valves where spring loaded "balance strips" seal off most of the top surface of the valve from steam chest pressure, greatly reducing the effort needed to move the valve.

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New balance strips fitted to a slide valve. The bottom of the steam chest cover is faced flat for thes strips to bear against. The two holes in the top allow any leakage to pass straight to exhaust.

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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: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 2:42 pm 

Joined: Fri Nov 11, 2016 10:17 pm
Posts: 32
Kelly, thanks for the photo.

What material do the balance strips wear against on the top? like a brass shim on the bottom of the cover?


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 3:28 pm 

Joined: Tue Sep 14, 2004 7:52 am
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Location: Strasburg, PA
Practically everything inside the cylinders and steam chests is cast iron running on cast iron. As simple as it gets.

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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: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 5:04 pm 

Joined: Tue Dec 11, 2012 1:40 am
Posts: 325
The good news is they have the same parts on the loco on the other side which will aid in getting new parts cast and machined. They will probably be asking for donations to help with repairs at some point.

Robert


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 5:14 pm 

Joined: Sun Aug 22, 2004 7:19 am
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Location: southeastern USA
[quote="BigBoy 4023"]The good news is they have the same parts on the loco on the other side which will aid in getting new parts cast and machined. They will probably be asking for donations to help with repairs at some point.

New parts cast and machined? Please fill us in on the particulars of the damage and what the root cause was.

_________________
Santayana: "He who does not remember the past is condemned to repeat it."
Corollary: "He who does is doomed to watch those who don't repeat it anyway."


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 Post subject: Re: Stretching her legs 63 years later
PostPosted: Fri Oct 26, 2018 8:30 pm 

Joined: Tue Dec 11, 2012 1:40 am
Posts: 325
That I do not know. I am just pointing out that they have the ability to make replacements fairly quickly. It could have been worse and been a one off part that would set them back quite awhile.

Robert


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