Stretching her legs 63 years later

softwerkslex · **Posted:** Sun Dec 09, 2018 3:46 am

Kelly Anderson wrote:

softwerkslex wrote:

ironeagle2006 wrote:

Most low pressure steam engine cylinders are designed for about 60-80 PSI if I remember my triple expansion steam engine setups right. The middle cylinder of those was low pressure the 3rd was very low pressure. Well you hit a cylinder designed for 80 PSI with a full shot of 200 PSI steam when it expands to try and condense back into water and things are going to break and bend. The back cylinders where exhausting to soon feeding higher than expected pressure steam into the front cylinders and things got bent. It would be like shoving a turbo from a C15 Cat OTR engine onto a VETC Honda 2 liter. Things are going to shatter.

i.e. too much pressure on the slide valve, causing it to seize, and then the momentum of the wheelset bending the return crank and link motion.

With all due respect, bull pucky! The LP cylinders of a mallet locomotive are not mechanically tied to the high pressure ones like a marine engine's are. If you introduce too much pressure into the LP cylinders of a mallet, the front drivers spin on the rail, and dissipate the excess pressure. Also don't forget that the slide valves are most likely balanced, and therefore less affected by pressure increases.

The answer lies elsewhere.

Yes, on second thought, I think so too. The LP cylinders can see full pressure with the simpling valve, so they should be able to take it. How about:

1) material obstruction in the valve chest
2) lubrication failure

softwerkslex · **Posted:** Sun Dec 09, 2018 4:15 am

Further......

I was involved in a restoration - intermittently, long time ago, where the first steam up, the engine had difficulty moving (I think the specific complaint was that reversing was near impossible). After cool down, we opened up the valve chest. One or more of those rectangular sealing pieces ("rings") that sit in the top of the valve were missing on one side. I think they were actually sitting loose in the valve chamber. I recognized what they were, but some of the others in attendance were not aware of their purpose. We put them back, and had no trouble with movement on the next fire-up.

It could be that someone was delegated to close up the valve chest on a volunteer work night, and they forgot or did not know to look and make sure those pieces were in place.

Dave · **Posted:** Sun Dec 09, 2018 8:11 am

Balancing plates. They are what prevents the full pressure from shoving the valve down onto its seat. Easy to imaging trying to manually reverse against that would be difficult.

Still trying to make sense of the explanation offered without success so far.

John T · **Joined:** Sun Sep 14, 2014 5:05 pm **Posts:** 1228

Let's just say, hypothetically, that a loose object like a nut or bolt was left in the valve chamber.

J.David · **Posted:** Sun Dec 09, 2018 6:54 pm

Or again, hypothetically, a collection of of old beer cans, etc. and/or cuttings from a one pass knife type tube cutter, left in the steam passages.
After doing our first tube job on Valley Railroad's No.40, we blew out the steam passages prior to installing the valves. Even though we had carefully covered the exhaust nozzle opening with rags under a plywood cover that was bolted down where the exhaust nozzle mounted, after blowing out the passages (with full boiler pressure), I found cuttings from a one pass knife type tube cutter out in the parking lot ahead of where we had blown out No.40...
Be well,
J.David

hamster · **Posted:** Sun Dec 09, 2018 11:23 pm

Here's a similar, but much more catastrophic real life incident similar to what happened to Skookum.
https://www.facebook.com/railroadfools/ ... =3&theater

Kelly Anderson · **Posted:** Sun Dec 09, 2018 11:52 pm

John T wrote:

Let's just say, hypothetically, that a loose object like a nut or bolt was left in the valve chamber.

That would do it. An engine that I worked on had surprisingly little clearance between the valve yoke and the steam chest, IIRC less than1/4" on each end. A good sized nut left in the steam line can certainly ruin your day.

choodude · **Joined:** Wed Jun 29, 2016 11:58 am **Posts:** 251

I'd imagine that this is an official enough announcement as to where Skookum is going:

Niles Canyon Railway will host 'Skookum' during celebration of the first transcontinental railroad

http://trn.trains.com/news/news-wire/20 ... l-railroad

Brian

John T · **Joined:** Sun Sep 14, 2014 5:05 pm **Posts:** 1228

The Skookum preformed wonderfully March 2 & 3. There were a few miner problems to work out but she put on a great show on several runs from Garibaldi to Rockaway Beach. A run to Wheeler was planed for Sunday but I had to get home. Many thanks to Chris Baldo, Scott Wickert and all the crew.

John T · **Joined:** Sun Sep 14, 2014 5:05 pm **Posts:** 1228

The Skookum arrived at Niles Canyon RR yesterday.

Kelly Anderson · **Posted:** Mon Dec 30, 2019 2:10 pm

Sort of off topic, but I clicked on this YouTube video because my grandfather's Army service in WWI was building bi-planes in Washington state, when at 1:48 into the video, what did I see?!? It's just for an instant, but there is no mistaking Skookum's unique shape.

John T · **Joined:** Sun Sep 14, 2014 5:05 pm **Posts:** 1228

Yep! Rhat's her all right. Note that the Heisler is lettered for Larkin-Green Skookum's second owner at Blind Slough.

Stretching her legs 63 years later

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