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White Pass & Yukon Piston Rod Failure
https://www.rypn.org/forums/viewtopic.php?f=1&t=35354		 Page 1 of 2
Author:  softwerkslex [ Sat Jul 27, 2013 7:15 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
Is it a piston rod failure or a water slug smacking the head? Or maybe the piston fractured into pieces and then hit the head.
Author:  EBTRRM1 [ Sat Jul 27, 2013 7:47 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
The piston rod broke through at the cross head wedge slot allowing the rod/piston to shoot forward taking out the front head. Hopefully it didn't crack the cylinder casting around the studs that are now bent. The piston also shattered in the process.
Author:  mikefrommontana [ Sat Jul 27, 2013 7:51 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
In looking at the second video, it appears the piston failed which then blew the head. In the first video, the crew walk back two cars from the engine and flip over a piece of iron which appears to be the cylinder head cover, with a hole in the middle from where it might have been torn from the cylinder head.

At least it wasn't the rear cylinder head, or failure of the cylinder block. I hope the WP&Y folks will get the engine back on its feet.

Michael Seitz
Missoula MT
Author:  Dave [ Sat Jul 27, 2013 10:12 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
It sure looks like EBTRRM1 has it right......you can see the stub in the crosshead and no tapered end left on the piston rod. The piston failure is probably due to the piston blasting through the cylinder head, which broke through the studs as it is supposed to in the event of a catastrophic failure like this one - this is why we turn those narrow bits in the studs when we make them. The piston itself is probably a cored iron casting which shattered through the outer walls of the core.

An oops like this can ruin your day, but unless there's more substantial damage to the rods, crankpins, crosshead or front flange of the cylinder itself, it's really not a huge job - just a new piston, rod and rings, then new studs and head - all parts that were regularly replaced due to wear in service.

dave
Author:  AndyPullen [ Sat Jul 27, 2013 10:35 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
Typically the studs holding the heads on the cylinders have a groove machined in them to weaken them just so the heads and cylinder castings won't be destroyed in the event of a failure like this.

Hopefully, the shop forces made the studs to fail like they are supposed to.

Andy Pullen
Author:  EBTRRM1 [ Sat Jul 27, 2013 10:53 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
From the grainy video it appears that maybe only two studs broke like they where suppose to. The one just under the piston valve and the next one to the right of that. The rest look intact/full length except they are splayed out in a radial pattern.
Author:  Trevor Heath [ Sat Jul 27, 2013 11:38 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
Rods were bent in another incident in 2010. They were removed and sent south for refurbishment.

A replacement set, held back and stuffed under a bench when the sister locos were sold in the 1960's were then pulled out, cleaned up and fitted.

TH
Author:  sbhunterca [ Thu Jul 24, 2014 8:09 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
CBC's report:

http://www.cbc.ca/news/canada/north/9-injured-as-train-derails-on-historic-yukon-to-alaska-railway-1.2716668

If the White Pass had to have a derailment, there are much worse spots than this for it to happen!

Steve Hunter
Author:  softwerkslex [ Thu Jul 24, 2014 8:13 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
Bummer.

Is this downhill, and the reason for the jacknife behind the engines?
Author:  Chris Webster [ Thu Jul 24, 2014 10:12 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
softwerkslex wrote:
Is this downhill, and the reason for the jacknife behind the engines?


According to posts in this thread on the Narrow Gauge Discussion Forum, the train was moving upgrade and there is a spring switch (photo) at the derailment location.
Author:  Bobharbison [ Thu Jul 24, 2014 11:34 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
The derailment doesn't look too bad until you notice the first coach. Wow, that's pretty serious stuff.

Meanwhile, the first half of this was from an incident in 2013 (why not start a new thread for the second incident?) What was the damage to the piston and how were repairs made?
Author:  softwerkslex [ Sun Jul 27, 2014 12:32 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
So, the engines split the switch, and then the second truck of the lead coach took the diverging route?
Author:  Brian Norden [ Sun Jul 27, 2014 10:24 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
For an overhead view see this post on the NGDF:
http://ngdiscussion.net/phorum/read.php?1,270102,270309#msg-270309

view is from a Facebook account:
https://www.facebook.com/photo.php?fbid=795943140438415&set=gm.542826609177321&type=1&theater

Four cars derailed and the first two almost went into the lake. It appears that the safety chains worked!
Author:  p51 [ Wed Jul 30, 2014 1:35 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
What's the exact location of the derailment?
Author:  Bobharbison [ Wed Jul 30, 2014 4:48 pm ]
Post subject:  Re: White Pass & Yukon Piston Rod Failure
Found this deep in one of the articles:

Quote:
The 15-car train reportedly derailed near Mile 20 of the railroad, northeast of Skagway.


I hadn't realized there were that many coaches in this particular train. That helps explain the jacknifing on the first two cars. Locos fall off, dig and and stop quite quickly, and all that weight just keeps on shoving. Something's gotta give and it does.
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