Please identify mystery linkage on this 0-6-0

[nkalanaga]

Doug:  That was my understanding.  There would be steam in at least one cylinder when the loco stops, and as it sits, the steam cools and condenses.  As you said, water won't compress, so the next time that cylinder is compressed, enough water can damage the piston, or rod, or even blow the cylinder head off.

As far as I know all steam locos had these.  However, there was a "starting valve", which Chris333 suggested, on some engines. I Googled "starting valve", and came up with two different valves, neither of which should be on an 0-6-0 cylinders.

The first is on compound locomotives, especially Mallets, and allows high pressure steam into the low pressure cylinders when starting, before the high pressure exhaust is available to work them.

The second is part of the throttle, and should be in the steam dome.  It seems to be a small "auxiliary throttle", which, when opened, allows the main throttle valve to open easier against the boiler pressure.  One page that described that mentioned that the D&RGW's K-37s didn't originally have them, and to open  the throttle from a stop, the engineer had to pull hard enough that, when the throttle finally opened, he'd end up pulling it fully open.  That led to a lot of slipping!

There may be other "starting valves", but those are the two I found.

[mmagliaro]

In your photo right about at the pilot beam there is a pivot. That pivot is a bar that goes over to the other side. On the other side the lever goes from the pivot bar down just like this side, but with no long lever sticking up. Moving the bar from the cab operates all 4 valves at the same time.

A Grandt Line On3 and On30 Porter kits contain all of these parts. I'll dig up the instructions when I get home.

Rod from the cab could be round or flat. Levers up front would be flat bar. Lever from the front to rear valve is flat bar.

I could draw a pic of all this if I was at home 

Like I said look at a Shay because all of this is right in your face on them.

Ack!

Yes, now that I realize there would not have to be another long control linkage on the other side, just a connection through the frame to the pivoting part we see in this photo, I looked at a left-side shot and I see the same arrangement of linkages.

Well well well, this just turned into quite a whole bunch of delicate little parts to model. 
The HO brass models of this engine do not have this linkage.  They only have the one rod across the bottom
of the two cylinder cocks, but nothing else connected to that.  Too bad.  I could get some really good photos from a large-scale brass version.

[Doug G.]

Oh well, HO, whatta ya gonna do?



Doug

[Point353]

The HO brass models of this engine do not have this linkage.  They only have the one rod across the bottom
of the two cylinder cocks, but nothing else connected to that.  Too bad.  I could get some really good photos from a large-scale brass version.

This model seems to have that linkage included:


http://brassdepartment.com/models/wr-enterprises-sps-a-1-0-6-0-steam-locomotive-usd1350-00/

You can see a reflection off the top of the vertical part of the linkage, just underneath and about one-third of the way back from the front of the smokebox, above the gap between the cylinder and the pilot.

[Chris333]

Well to be fair it is hard to see even on the real thing. Hard to even find a photo showing it.

I usually just mount 2 small stanchions under there and thread a wire through. You could add the lever and long rod and call it done.

[Doug G.]

That is an EXTREMELY fine model.

And, this is all a very fascinating thread. It seems the acquisition of knowledge about those incredible machines is never-ending.

Now, all Max has to do is figure out how to make steam come out of the bottom of the cylinders of his 0-6-0 right before starting it.



Doug

[Chris333]

Those Porter instructions, this is an O scale model.


You can see the lever here behind the cylinders:

Different locos had different lever arrangements.

And here is a crappy drawing of how it would look from the front.

[Chris333]

This shows how they operate on a model shay:

[mmagliaro]

Aha!  So, I already had the photos of those W&R brass models.  I don't know why I didn't see this before. 

So, here is a very close crop on the highest-resolution prototype photo of SP&S #4 that I have.  And in fact, you can see in this picture that the rear drain is blowing steam so they must have been just starting the engine moving in this photo!


Now, here is a close shot of the W&R model. 


One thing I don't get.  The prototype looks to me like the linkage connects to the rod somewhere between the two drains, whereas on the model, it is depicted as connecting to the front.  And in the prototype photo, the rod through the two drains does extend well past the front drain and even seems to have a hole in the forward tip of it.  It looks to me like perhaps it *used* to connect there, on the front tip, but was altered and now connects more in the middle in this prototype shot.  Note how the rod through the two drains isn't a round rod at all, but more of a flat bar (even though the HO model has a piece of round wire in there)

But honestly?  It will be much more practical to just let the curved linkage come down and rest on the
rod going through the two drains, the way the HO model is done.  Even on the HO one, they compromised and just have the curved link resting there without any actual joint.

[Chris333]

The shop could have changed it up over the years. Working on the cylinders is probably common.

Still look how close you had to look to even see it. Try not to lose too much sleep 

[OldEastRR]

The LL/Walthers Berk and the Bachmann TenWheeler both have the drain cocks and linkage molded on the cylinder bottoms, just no linkage from them to the cab.  For all you rivet-counters wanting exact models all you need do is add the long rod. 

[Lemosteam]

Drift for edification.  I realize Max is simply trying to model these parts, but:

OK, so what type of valve is that in the bottom of the cylinder?  With a fore-aft motion based on the linkage, that must be some kind of sprung lever valve, otherwise how would it close to maintain cylinder pressure?

Maybe a sprung vertical check valve but that would require additional levers to convert the fore-aft motion to up-down.

The steam release appears to be exiting outboard from the valve and not down as well.

[mmagliaro]

Drift for edification.  I realize Max is simply trying to model these parts, but:

OK, so what type of valve is that in the bottom of the cylinder?  With a fore-aft motion based on the linkage, that must be some kind of sprung lever valve, otherwise how would it close to maintain cylinder pressure?

Maybe a sprung vertical check valve but that would require additional levers to convert the fore-aft motion to up-down.

The steam release appears to be exiting outboard from the valve and not down as well.

I wondered this too.  That long linkage from the cab looks very flimsy, and you can see that it is even bent and skewed all over the place along its run from the cab to the front lever.   I wondered how such a relatively sloppy connection could ever work to open and close valves.  Remember, even on a small engine like that, that long rod runs about 22 feet.  So there's going to be an awful lot of play in it.

By the way, one of the things that makes that long rod and link so tricky in a model is that unlike the prototype, it cannot "connect" to the linkages down by he cylinders.  If it did, I couldn't get the engine apart.  It has to have a little hole and pin, or something similar, to allow it to seamlessly disconnect when I slide the cylinder saddle out and the boiler off.  The brass model achieved this by just having the downward vertical lever lie on top of the link across the underside of the cylinder.  Not a bad idea.

[up1950s]

Makes me wonder if all steam had cab controlled cylinder cocks , but maybe pneumatic or steam powered to a small activation cylinder buried under and between the steam chest with linkage to the cylinder cocks from there . We need under shots from wrecks .

[peteski]

I seem to recall seeing ones that looked like ball-valves.  So they would go from fully  closed to fully opened in a 90 degree rotation.  My initial post on this thread linked to an online discussion where I think automatic drain cocks were also mentioned (but that might have been elsewhere).  Just do a Google search for "steam loco cylinder drain cocks" and there is some good info available (although most seems to be referring to large scale live-steam models).