# Unit Shop Steam Oil Ring Dam for Accucraft locos



## Two Blocked (Feb 22, 2008)

My opening photo is of a Unit Shop inspired Ring Dam that I built for my Accucraft B&O, sloped back tendered, 0-4-0 goat. The loco had a high lube oil consumption rate, but more than that it was slopping up the track rails with slippery condensate. As I remember I used a 1/2" length of 11/32" dia. K&S brass tubing, saw-split down one side to make the dam.










That's the ring dam prior to slipping it into place with my fingers, and then positioning it in place by screwing down on the reservoir's oil cap.










This gadget works by restricting the flow of steam into the steam oil reservoir, and thus the flow of steam oil out and into the steam flow to the cylinders. The slot in the oil dam is indexable through a 180 degree arc so that the steam oil's rate of flow can be adjusted to suit the engineer's fancy. 90 degrees, as shown, is a very safe place to start the adjustment process.

I have done this to six local locomotives that include the C-25, SP-12, two engine Shay, 1:29 0-6-0 Yard Goat, and something else I forgot about. My SP-12 has been running with a ring dam for five or six years with no problem. Some locos, the Shay and the 1:29 for instance, need to have the ring dam made from 5/16" dia. brass tube.

One of my steamup buddies who holds dual citizenship [he steams up in both Roseville and Sacramento] told me yesterday that the Roseville steamers have fitted ring dams to their C-25's and have forgone the "double-nutted" Accucraft sorta-fix that the factory first suggested to address the problem.


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## Charles (Jan 2, 2008)

Kevin

Thanks for the post on a fix that annoys both owners and fellow steamers in regards to excess oil everywhere.


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## Semper Vaporo (Jan 2, 2008)

Question:

I am trying to figure out the path for the steam and oil to exchange. If the sleeve were to cover the port where the steam line and the reservoir connect then no oil would enter the steam path.

Is the tubing loose in the chamber such that steam pressure pushes it aside and that allows some oil to pass the other way at the same time?

Or do the threads in the reservoir body for the cap extend below the port, such that when with the split tubing is inserted, the steam and oil path is restricted to following the path formed by the tubing and the threads. I perceive that to be a pretty narrow path and would probably work well to reduce the quantity of steam and oil exchanged.

Do the threads extend that far down on all incarnations of the Accucraft oil reservoirs?

I think a warning is in order here that SOME oil MUST enter the steam path. I say that because I remember a post many years ago where a newby soldered up the hole completely and bragged that he was not using any oil at all anymore and never had to drain water from the reservoir!


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## weaverc (Jan 2, 2008)

After doing a lot of messing with both the Accucraft hydrostatic and displacement lubricators, my solution, as that of others also, was to install a Regner hydrostatic lubricator. It is a precision device that is easy to install with the only soldering being the compression fittings on the ends of the 3 mm copper lines. The 40405 is a good substitute as it holds about the same amount of oil as the Accucraft one does and the 40404 holds enough oil for 3 to 4 runs of a large locomotive. I did modify the cap with a handle. Also, I mounted it on the floor of my C-25 instead of through it, so the drain is not accessible and a syringe has to be used to empty the grunge after a run. It works perfectly.


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## Ray Cadd (Dec 30, 2008)

Funny, I had this same idea, but never carried it to fruition. Semporo raises the same question I do; exactly how does the oil enter the path in what I'm seeing as the 'closed' (90deg.) position? It would seem to me, the slot would have to at least partially engage the weep hole. And, the fit would have to be tight enough to keep the sleeve in place.


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## weaverc (Jan 2, 2008)

A displacement lubricator is supposed to lubricate the inner working parts of the cylinders. It is called a displacement lubricator because of the way the condensed steam displaces the steam oil in the chamber. The lubricator has a filler cap at the top and drain at the bottom, both of which have o rings to seal against the internal pressure. The steam pipe from the throttle valve passes through the chamber and has a very small hole in it. This hole is the only thing that allows the exchange of steam and oil. Here is how it works.

As steam passes through the steam pipe from the throttle valve, through the lubricator to the cylinders, some steam enters the chamber via the hole in the pipe. Because the lubricator is cooler than the boiler, the steam condenses into water which then sinks to the bottom of the lubricator because it is heavier than the steam oil. This in turn causes a pressure that displaces the oil upwards. A small amount of steam oil passes out through the same hole and is carried along with the steam to the cylinders.

The apparent issue with the C-25 and the displacement lubricator that came with it, which I discovered while evaluating it for a Steam in the Garden review, is that the hole in the steam pipe through the lubricator is too large. When the cylinders and steam pipe are cold and not yet warmed up, water passes into the lubricator instead of steam and displaces large amounts of oil early in the run. Not only does it make a mess, but the oil only lasts about 20 minutes. One solution is to refill the lubricator once the cylinders are warm and the oil should then last the entire run, but the splatter mess is still there.

My first thought was to change to an Accucraft hydrostatic lubricator, which I did. But that also had issues. The main one was that the hole in the steam line was aligned with the shaft of the adjustment needle and not aligned with the tapered part of the needle. No steam could pass by the shaft into the lubricator. Also, the threads on the needle were too short to back the needle out enough to expose the taper to the hole. The second issue was that the cap when inserted to the gasket was too deep and also blocked the hole. The apparent solutions are to drill out the center of the cap with a ¼ inch drill to create a head space over the steam hole and to close up the original hole and re-drill it so that it is aligned with the tapered part of the needle valve. BUT, I elected to NOT modify the lubricator and changed to a Regner lubricator which works perfectly and can easily be modified to fit in an Accucraft locomotive. See my reply with a photo below.


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## jfrank (Jan 2, 2008)

I sleaved my C25 with the 11/32 tubing something similar to what is illustrated and it cut down the oil flow significantly. Later on all of us here in houston switched to the Accucraft adjustable llubricator. As far as I can tell ours are working. The sleave, however, also works and saves the $80 purchase price for a new lubricator. I plan to retro fit some of my other oil hogs with the sleave arrangement.


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## Dwight Ennis (Jan 2, 2008)

So are people saying here that the new Accucraft C-25 does NOT have the newer adjustable lubricator?


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## weaverc (Jan 2, 2008)

Dwight,
I discovered this with my C-25 and reported it in the review I made for Steam in the Garden. The hydrostatic lubricator was on the engineering sample, but according to Cliff Lusher, it was removed and replaced with the old type because they had been having trouble with the hydrostatic on a previous locomotive. Not all hydrostatics are bad, but evidently there are production issues with the hole being drilled in the wrong place. Unfortunately, the displacement lubricators on the C-25 are also troublesome because of the high rate of oil use, which I also reported in my review.


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## roadranger (Jan 6, 2008)

Can you actually regulate the oil flow by turning the sleeve? 
Or is it a one flow rate sleeve where it does it not matter where the slot in the sleeve is located, as long as the steam/oil hole is blocked by the sleeve?


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## Semper Vaporo (Jan 2, 2008)

I want to point out a difference between "Hydrostatic Lubricator" and the common "Displacement Lubricator" as used on most small locomotives (more properly named a "Roscoe Displacement Lubricator".

The Hydrostatic and Roscoe are both "Displacement Lubricators", but they are not the same. Roscoe Lubricators scale down well, but a true Hydrostatic Lubricator does not, nor is there always room for the additional pipes used by a Hydrostatic type.

The Roscoe Displacement Lubricator injects a small amount of oil into the main steam pipe, so there is both steam and oil in the portion of the main steam pipe from the reservoir to the steam chests of the engine.

Whereas a Hydrostatic Lubricator uses steam pressure to push oil in separate pipes to any places needing lubrication (not just the steam engine itself) and there is not supposed to be steam/water present in those pipes (you don't want steam/water in the journal bearings of the axles, Dynamo, etc.!)

In a Roscoe Displacement Lubricator, an amount of steam enters the oil reservoir from the main steam line between the boiler and the engine. The steam condenses to water, which sinks to the bottom of the reservoir because water is denser than oil. The water thus displaces an equal amount of oil, which is then forced out the same opening by which the steam entered. The distance between the main steam line and the reservoir can be just the thickness of the wall of the steam pipe or a longer pipe that Tee's into the main steam pipe. It is still debated as to whether there is a simultaneous flow of steam into the reservoir and a flow of oil out, each passing the other in the pipe between the main steam pipe and the reservoir, or if the steam and oil take turns in pulses through the connection.

In a Hydrostatic Lubricator, the steam line to the reservoir is dedicated to supply steam just to the reservoir to pressurize it. Some of the steam condenses and sinks to the bottom of the reservoir and thus displaces the oil. The oil exits via any number of separate pipes to appliances on the locomotive that need constant lubrication. At least one pipe will go to each steam chest where the oil exits the pipe directly into the steam chest to lubricate the valve mechanism (D-valve or Piston-valve) which then drains (or is picked up by the flow of steam in the chest) into the power cylinder to lubricate the power piston. Each pipe out of the Hydrostatic Lubricator has a valve to regulate the amount of oil that exits. Each pipe also has a sight glass for the operator to monitor that no water is entering the pipe. The user is supposed to monitor a separate sight glass near the top of the reservoir and when water is detected there then the reservoir is full of water and the oil supply is exhausted. The steam is then shut off and the water in the lubricator is drained via a valve in the bottom and the reservoir is refilled with oil via a (sealable) port in the top. Unlike the Roscoe, no oil exits via the steam supply pipe.

There are problems with the Roscoe Lubricator...

1) The oil sometimes will only go to one of the steam chests, leaving the other one with no lubrication. It is unknown why this happens, but it has been documented by several of the early Live Steam enthusiasts.

2) If the throttle is left open on the boiler during the cool down phase and no other way is provided to allow air to enter the boiler to take the place of the condensing steam, then the vacuum caused by the condensing steam draws oil back through the throttle, thus contaminating the boiler. There are other ways to relieve the vacuum. One is to open the blower valve (is so equipped). Another is if the boiler has a Goodall Valve installed (the one-way seal of a Goodall will allow air to enter when the pressure inside the boiler is less than the atmosphere outside).

The problems with the Hydrostatic Lubricator...

1) The necessity of a valve to regulate the steam supply and separate valves for each oil pipe.

2) The additional piping necessary to convey the oil to each location it is needed.


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## BigRedOne (Dec 13, 2012)

Thanks for that detailed explanation, SV.


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## JoelB (Jan 3, 2008)

I'm not certain about how the oil ring dam (aka "sleeve") that was the original subject of this thread actually functions...in order for this to work (and not completely block the flow of oil to the steam line), there has to be some minute clearance between the outside of the sleeve and the inside of the lubricator body. Anyone have an idea what that is, and if there's an ideal measurement? And if that's the path that the oil takes to get to the steam line, how does moving the dam change the flow?


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## roadranger (Jan 6, 2008)

Joel, that's what I'm wondering too. 
My guess is; the steam/oil flows along the threads from the cut out section to the piping hole. 
Then maybe the closer the cut out is to the hole, the more oil flows? 

Maybe Two Blocked will come back with a definitive answer...


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## jfrank (Jan 2, 2008)

I pushed the sleeve out a little where the steam line hole is. It worked very well for such a simple solution. I only slit the tubing part way. There are probably a few diff ways to do this. But the main idea is really simple and easy to do.


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## Two Blocked (Feb 22, 2008)

Yes, the oil flow to the cylinders is somewhat dependent on the position of the slotted portion of the ring relative to the steam port in the oil tank. The further the slot moves away from the steam port, the less steam enters the tank. The less steam condensing in the tank, the less steam oil is forced out of the tank and into the steam line to the cylinders. My advice is to start to experiment with the slot 90 degrees away from the steam port. I first ran on rollers with a sheet of white paper under the smokebox to catch waste oil. With this as a benchmark, I started to further move the slot away from the steam port to reduce the uptake of steam oil. My setting is now at 5 pm with the steam port at high noon. Cliff tells me that they are making this approach known to customers that are asking about excess oil consumption. Everyone who has tried this approach to lubrication control on the C-25 series loves its simplicity and effectiveness.


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