Steam & Excursion > SPNG # 18 stubbed it's piston

Just received these images of SPNG # 18 today.
She blew a piston ! - near Rockwood
I don't know any more details. photos from W. Pettersen and Allen Pollock
 

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Hopefully the bore isn't badly scored, at any rate that's not good news.

Out

Is this what happens when you don't have all your water fully drained from your cylinder cocks or something else?

If the cylinder was full of water it likely would’ve blown the entire head off. The way it punched a hole leads me to think something came loose.
Unfortunate but they will get it fixed!

Posted from iPhone

Are the piston and cylinder head both cast?

up3985 Wrote:
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> Is this what happens when you don't have all your
> water fully drained from your cylinder cocks or
> something else?

Judging by photos elsewhere, it's a slim chance it was water in the cylinders.   The incident happened some 15 miles from Durango.

Looks like something worked loose on the piston rod until it struck the head.  I'm sure things got exciting.  Hope it didn't do damage to the cylinder casting.   Tough luck.

Probably the cross-key, or other securemrnt, locking the piston rod to the cross head failed.

Notice that the cylinder head was knocked in the center... the end of the piston rod is what went through the head.. Looks like it was a cast piston & shattered...

With slide valves, in case of “hydraulic lock” ( water in cylinders) you would not have the center of the head broken out.

It was common with slide valves to slightly lift off their ‘seat’ and relieve the water pressure... piston valves don’t do that relieving action..

You need a picture of the cross head, and the back end of the piston rod..

W.

( Been THERE, done THAT, got the
tee-shirt...)

Posted from iPhone



Edited 1 time(s). Last edit at 04/09/19 13:56 by wcamp1472.

It appears to have been a lubrication issue.

Posted from iPhone

GrandePete Wrote:
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> It appears to have been a lubrication issue.

What do you see in just those few photos to make such a deduction?

I was shooting video of it when it happened. It sure made a lot of racket!  I'll post it on my channel Saturday.

Well, guess it does show, that the D&SNG and C&TS shop personnel do a good job of maintaining their steam fleet. 

Not saying anyone is any worse, but to be able to maintain a daily active roster, year after year after year, says something about the skill level of the crews. 

Mike ONeill
Parker, CO

wcamp1472 Wrote:
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> Probably the cross-key, or other securemrnt,
> locking the piston rod to the cross head failed.
>
> Notice that the cylinder head was knocked in the
> center... the end of the piston rod is what went
> through the head.. Looks like it was a cast piston
> & shattered...
>
> With slide valves, in case of “hydraulic lock”
> ( water in cylinders) you would not have the
> center of the head broken out.
>
> It was common with slide valves to slightly lift
> off their ‘seat’ and relieve the water
> pressure... piston valves don’t do that
> relieving action..
>
> You need a picture of the cross head, and the back
> end of the piston rod..
>
> W.
>
> ( Been THERE, done THAT, got the
> tee-shirt...)
>
> Posted from iPhone

I believe it's like Wes said, illustrated in this pic of another engine (D&NM 14).  The Piston Rod (A) is press fit into the crosshead (B).  Don't let the hex shape of the boss on the crosshead at (C) fool you.  It is pure compression, and is not a fitting tightened by turning a nut at (C) - there is no nut.  The boss is just shaped hexagonally on this particular engine.  A brass (or steel) wedge just above (D) in the photo is driven into a keyway in the crosshead and the piston rod to double protect the press-fit connection of the piston rod and the crosshead.  The key itself may be further triple protected from falling out by a screw, bolt, or rivet.

It appears to me that this particular failure was a "perfect storm" of multiple protective measures all failing at the same time. 

-LD

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Now the question is how long will the repair take. Mostly how long to manufacture the parts.

Well, could they "borrow" some parts from sister #9 in Laws, CA.?

Is there any valve oil in the cylinder? Looks completely dry to me.

Dreamer

Posted from Android

Dreamer Wrote:
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> Is there any valve oil in the cylinder? Looks
> completely dry to me.
>
> Dreamer
>
> Posted from Android

Because you can absolutely tell from that picture looking into the dark cylinder. Normal circumstances anyway it's just a thin coating, not oozing and slopping all over.

Brasspounder Wrote:
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> Dreamer Wrote:
> --------------------------------------------------
> -----
> > Is there any valve oil in the cylinder? Looks
> > completely dry to me.
> >
> > Dreamer
> >
> > Posted from Android
>
> Because you can absolutely tell from that picture
> looking into the dark cylinder. Normal
> circumstances anyway it's just a thin coating, not
> oozing and slopping all over.

It would be nice to see a thin coating on part of the pieces. Even if the lubricator was shut off with the incident there should have been a line slowly drooling oil from the line. SP instructions speaks of starting feeds for several minutes prior to start. Based on what I can deduce from the photos, those appear to be overload failures due to the cleavage pressent in the breakes.

Does 18 normally live at the D&S or was it just visiting?

filmteknik Wrote:
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> Does 18 normally live at the D&S

No.

or was it just
> visiting?

Yes, in order to train their crews on oil firing.