Re-facing Slide Valve & Ports

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Re-facing Slide Valve & Ports

Post by Builder01 »

Hi Bill,

I have pulled the forward cover off the cylinders, and they seem to be just fine. I am using graphite yarn/string in the "ring" groove of the piston. This seems to be working well.

In fact, every time I have opened a steam chest, there is always evidence of remaining steam oil, but I think there is not always enough when running. There are occasional "squeeking" sounds while running for some time, and then it stops. So, this is intermittent and difficult to trouble shoot. Probably there is sufficient steam oil for the pistons, but, not for the "flat on flat" of the slide valve to the port face.

As previously mentioned, my lubricator is moving only one "click" per oscillation of the pump rm. I am going to see if I can connect the motion closer to the pivot of the lubricator and get two clicks. I'll see if that makes a difference.

Better to have too much rather than too little. I think I may have too little right now.

David
User avatar
Bill Shields
Posts: 10464
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Re-facing Slide Valve & Ports

Post by Bill Shields »

if you see any oil at all, that is more than enough...by all means check that it is working, but if you see any oil all should be ok.

Have you ever seen how little oil a full size steamer actually used (all things considered)? Our little locos typically DROWN in oil by comparison.

I would think more 'dirt' and the result(s) of dirt.

silly question: but it the oil getting to both cylinders equally? I know this sounds like a silly question, but it pops up more often than you would think.
Too many things going on to bother listing them.
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Re-facing Slide Valve & Ports

Post by Builder01 »

Bill,

Well, I do not know for 100% sure that the oil is getting to each cylinder equally. The oil enters at the bottom of a sort of T that is also fed by the main steam from the throttle . Each leg of the T goes to a cylinder. The "damage" to the port face is quite equal on each cylinder.

So, I assume that what oil is getting, or not getting, to each cylinder, is pretty much equal. This leads ms to believe that whatever is happening, is equal.

Perhaps dirt is an issue, hard to tell or to know.

As for my lubricator, it is a single "cylinder" little pump. It sucks oil into it's pump cylinder for half of a revolution of the ratchet wheel, and then is pumping it out for the other half.

David
User avatar
Bill Shields
Posts: 10464
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Re-facing Slide Valve & Ports

Post by Bill Shields »

pretty standard stuff. doubt it is lack of lubrication I this case..
Too many things going on to bother listing them.
RET
Posts: 960
Joined: Wed Jun 07, 2006 8:36 am
Location: Toronto, Canada

Re: Re-facing Slide Valve & Ports

Post by RET »

Hi,

Two things:

Does your locomotive have "snifter valves"? If it doesn't, then you could be drawing ash in through the blast pipe as far as the exhaust port. Over time that could cause your problem.

Second, Are both parts wearing equally? If the port faces are wearing more, then there could be dirt or ash embedded in the valve face.

Finally, If this is 7 1/4" / 7 1/2" gauge, because of the size of the valve, the pressure on the valve faces will be several times the steam pressure, potentially at least several hundred pounds. Because of this, you might consider a balanced valve design even although it is more complicated.

However, when you look at Bill's pictures, you can see that others don't have your problem, so its just a case of finding the underlying cause, whatever that may be.

Richard Trounce.
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Re-facing Slide Valve & Ports

Post by Builder01 »

Richard,

Yes, I do have a snifter valve. It is a single one piped to the hot header of the super heater tubes.

The loco is a 1" scale, so, the valves are not as large as a 1.5" scale.

I think the root cause of all of this may be the lubricator. I have been given a suggestion from someone a way to test to see that the lubricator is actually delivering oil at a pressure greater than the boiler.

The problem is, when you close the throttle, the lubricator may be pumping oil, but it's not working against the boiler. Then, you open the throttle, and whatever had been pumped into the steam line, when the throttle was closed, will be blown into the steam chest, until that runs out. So, you do actually get some oil into the steam chests and cylinders, but not as it really should be if the lubricator is delivering when the throttle is open to boiler pressure.

David
RET
Posts: 960
Joined: Wed Jun 07, 2006 8:36 am
Location: Toronto, Canada

Re: Re-facing Slide Valve & Ports

Post by RET »

Hi David,

What you say makes sense. At least 10 years ago I made 3 lubricator pumps and put two of them on the 3 1/2" gauge Boston & Albany (one on each side). They worked fine, the only issue I had was with the discharge check valve sealing. The least bit of dirt would cause the check valve to leak and blow back into the pump reservoir blowing all the oil out. I came up with my own simple soft seat check valve design and I've had no problems since.

When I made the pumps, I used graphite packing on the ram gland seal and the spring I used that applies pressure between the pump body and the ram housing was evidently strong enough that the ram pressure didn't leak away so they worked.

Because the pump delivery rate is so low, any leakage at all at those two points would give the result you are talking about. I used 1/8" dia. rod for the pump ram and the pumps are the simple L.B.S.C design. On the Boston & Albany, I believe the ratchet gives two clicks per revolution of the drivers. Because the Boston & Albany has stainless superheaters that extend into the firebox, I use a heavy gear oil in the lubricators, not a water soluble steam oil.

I haven't run the Boston & Albany for quite a while, I guess my main focus is in building, not running.

Hope some of this helps.

Richard Trounce.
southwestern737
Posts: 168
Joined: Sun Nov 12, 2006 8:45 am
Location: Magnolia, TX

Re: Re-facing Slide Valve & Ports

Post by southwestern737 »

Something in your last post caught my attention, you said “superheater”, our scale super heaters normally don’t get hot enough, but it is possible that your steam oil is not holding to the the dry steam, you my check the specs on Lycurgus steam oil. Just a thought.
Brent
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Re-facing Slide Valve & Ports

Post by Builder01 »

Richard,

The pump you describe sounds very similar to mine. The problems you describe will be part of my investigation of my pump when I get home, along with refacing the ports and valve. (On the road right now visiting a few tracks as my loco limps along!). My main focus is running, not building. For me, building, was a necessary evil to get a locomotive! Made my own copper boiler too.

David
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Re-facing Slide Valve & Ports

Post by Builder01 »

Brent,

This problem has happened just recently. For a year and a half, my oil and lubricator combination has been working well. (at least I think it has been okay!) So, something has changed recently. I am suspecting the lubricator, not the oil.

As for the super heater, that is what it is called in the drawing. I understand it is probably more like a steam "dryer" than a true super heater.

David
Mike Walsh
Posts: 955
Joined: Sun May 06, 2007 10:14 pm
Location: St. Louis, MO

Re: Re-facing Slide Valve & Ports

Post by Mike Walsh »

I just read through the whole thread, and one thing is not glaringly apparent to me, so forgive me if I accidentally glazed over it.

One thing that hasn't been mentioned here is the alignment of the valve stem and valve with respect to the valve deck. If any misalignment (and no provision for 'give' of the slightest angular difference, you could see your valve see-sawing into your valve deck. I've seen this on a 12" gauge 4-6-2 where the crossheads were so worn out that the piston was digging into the cylinder wall at the ends of the stroke.

I agree that CI valve should be considered. The Allen cylinders are CI with bronze valves. I've also seen a 12" gauge cylinder block in CI, with a CI valve. Over the years she started sounding lame. We finally gave up and pulled the valve chest. Found some pretty serious wear -- about 3/32" when you tip the valve from front to back. Needless to say the valve deck was stoned and the valves were re-ground. Sometimes these things just need a little TLC. But I suppose if you run your engine every weekend for ten years you're bound to see a little wear and tear.

If you're passing through St. Louis on your way back to the northeast, let me know. I know you have probably left Marty's by now.

-Mike
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Re-facing Slide Valve & Ports

Post by Builder01 »

Mike,

Since this "problem" is a recent event, I am pretty sure the alignment of the valve spindle to the port face is quite parallel. It has run well for almost two years. The valve is not "bound up" on the spindle and is free to float. It is held to the port face strictly by steam pressure. The groove that is wearing in the port face is pretty even from front to back. One of the challenges in refacing the valve is to make sure that the face remains square to the slot that the "nut" rides in. Depending on how badly worn the valve is, I may just take a skim cut on the shaper to re-establish to valve face.

I will not be passing through St.Louis, I'll be home this afternoon.

David
Post Reply