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[kno3]

Hello,

I am planning a steam plant for a twin screw ship model and it should have two engines with a single boiler. I was wondering what is better, to use a single lubricator for both engines or two separate ones.
So far I am thinking that two lubricators might be the easier way of making sure that both engines receive oil, but maybe this isn't necessary. A single lubricator would have the advantage of a simpler and lighter plant. What is your experience?

Please explain your vote.

[boatmadman]

I voted for 2, mainly 'cos it seems right to me. There probably is no real critical engineering reason to favour one or two.

With two, you can also have a nice symetric layout. I dont think weight will come into it really, lubricators arent heavy,and, any boat big enough to need/carry twin engines wont notice the difference in weight between 1 and 2 lubricators.

Ian

[benjaml1]

2 here too, because it seems to me ( with the limited knowledge I have) the right thing to do...

Having spent a lifetime studying and designing systems involving flows of liquids & gases, it is very difficult to plumb a system that shares flow equally without instumentation/controls, especially if the liquid is immiscible...

[HS93 (RIP)]

two you could never guarantee that both engines get the same amount.. if you have one oiler you would need to have it set to supply enough oil for both engines so double what you would normally supply , if you stop one engine maneuvering one engine then gets all the oil or double what is req..
my thoughts anyway
peter

[derekwarner]

kno3....I would strongly agree with the points put forward by benj & HS93......all valid & logical........you should use two independent [Winfreid Niggle quartz tubed] lubricators....Derek

[Circlip]

Untill just recently, the illustrious Bogstandard was prepared to put two on a twin cylinder engine. The toy train guys put one lubricator to feed two or more cylinders separated by frameplates or whatever.

  What you have ommited to tell us Kno3 is what TYPE of lubricator you are considering?? If a mechanical lubricator you should only need one, but for a Displacement type, where one should surfice, two looks and works in a more balanced view.

  Regards  Ian.

[kno3]

Hi guys, thanks for the answers. I don't know yet what kind of lubricator to use. I am inclined towards the Niggel fully adjustable displacement lubricators with glass tube (http://www.modellbau-niggel.de/Verdraengungsoeler-mit-Glaszylinder-410-113-i263.html ), but I have a mechanical one too.
Why would the type of lubricator make a difference?

[SteamboatPhil]

Although a displacement is as simple as you can get, and I would certainly fit one to each engine, as has been stated by benjaml1 trying to guarantee equal amounts to each from one source could be hit and miss (even fitting a displacement lubricating a D10 can be tricky) A mechanical lubricator is pumping and can be split equally between engines.
I have one lubricator on my loco for two cylinders and have never had a problem.   

[kno3]

Hi, how can you split the oil from the mechanical lubricator evenly? Mine has a single ram pump in it.

[benjaml1]

Hi, how can you split the oil from the mechanical lubricator evenly? Mine has a single ram pump in it.

With two flow paths & one source you will find the flow prefers one path over the other. This is because the "easy" higher flow path has the least restriction. One would put a variable restrictor in the easy path & trim to balance. Quite a crude system which will require trimming if temperature/viscosity/Cv change...

[kiwimodeller]

I have been thinking about this question for a little while. I am planning to link two double acting single cylinder oscillators together in my next paddler project. I was intending to fit separate displacement lubricators to each engine until I started contemplating the piping arrangements. Realy the engines are no different to say a V Twin oscillator and those seem to work fine with one lubricator. My concern with the two lubricators is that they would have to be fitted after the forward/reverse and throttle valve. This would mean that when the engines were in reverse the lubricators would effectively be in the exhaust piping and might well feed more oil in to the separator/condensor as there would not be any resistance to the passage of the oil. I also began thinking that perhaps there should be separate valves and separate condensors to ensure there was no backpressure from exhaust ports opening at different times. Now I am thinking I am worrying too much as the V Twin works fine with one lubricator and one condensor. Thoughts please, save me from lying awake at night pondering this! Thanks, Ian.

[benjaml1]

Would it be possible to post a sketch of your proposed pipework/flow diagram... It would get rid of any possible ambiguity

[geoff p]

Attached is an image of my mechanical lubricator.  It has twin-rams, operated by two cams opposed to each other.  I (sincerely) hope this will make a more continuous flow than would a single-ram, albeit also causing twice-the-flow of oil.
It is driven from a simple eccentric - about 4mm throw - tucked between the main bearings, and a ratchet-and-pawl to reduce its speed.



I intend to inject the oil upstream of the reversing/regulating valve, via a simple Tee-piece.

The black, plastic gear is only for concept-testing and will be replaced by a decent ratchet wheel when I can find one.

It does seem to me that a mechanical lubricator overcomes the lack of condensed steam while developing / running-in an engine on air - which was why I started making mine.

Geoff

[Circlip]

Ian (Kiwi) if you fit a single (Or two for that matter) displacement lubricator it/they must be fitted between the steam source and any controlling valves.

  Regards  Ian.

 Edit :- "on yer oscillator"

[benjaml1]

Ian (Kiwi) if you fit a single (Or two for that matter) displacement lubricator it/they must be fitted between the steam source and any controlling valves.

  Regards  Ian.

 Edit :- "on yer oscillator"

From someone not versed in model steam engines, may I ask why ?

[Circlip]

Sorry Benjaml, it was an ambiguous statement, for control valves I should have said reversing valves in the case of oscillators, due to the fact that the reverser is normally located on the port block in a single cylinder.

  Another misnomer for the displacement type lubricator is that there should be seperate steam inlet and outlets on one.

  Regards  Ian.

[benjaml1]

Thanks Ian... 

[kiwimodeller]

I had always thought the lubricator should be in the line from boiler to control valve and that is why I had come back to thinking that one large lubricator would have to do for two cylinders whether it was as two engines or two cylinders of one engine. My computer skills are not up to putting a drawing in my post but I will see if I can get some help with that however I have more or less decided that I will have to try just the one lubricator in the main feed line and just try and establish that both engines are getting oil. I may try it without the reversing valve in the line to begin with and that way I can run separate exhausts and look to see if oil comes out of both. Will keep you posted. Cheers, Ian V.

[benjaml1]

Try to keep the pipework that splits after the lubricator/control valve a mirror image of each other & of the same plane & you may well be in luck... You may test the system without the engines connected to see if it is "balanced"...

[kiwimodeller]

I have now bench tested (not terribly successfully but thats another story) the two single cylinder engines controlled by the one reversing valve from Dream Steam. The valve worked fine after a bit of tweaking so it would take more pressure than it is designed for. The displacement lubricator was fitted in the line from the boiler just before the control valve and I tried to make the pipes were equal lengths. I can report that both engines definitely received ample oil although I cannot prove they got equal amounts. Encouraging enough to make me want to perservere. cheers, Ian.

[tobyker]

I've added a home-made displacement lubricator in the steam line ahead of the DreamSteam reversing block in my ST V-twin. Apart from any other advantages, it lubricates the reversing block as well. Mind you, since I've sealed the drain screw I've not tried it again.