Mechanical Lubricator Question

[runner42]

Hi all,

I have made a mechanical lubricator for my LMS Black 5 as per LBSC's instructions. I now want to test it to see if it works OK. What sort of oil pressure output should the mechanical lubricator provide to overcome the oil check valve and provide oil to the cylinders and is there an easy way to test this?

Thanks in advance,

Brian

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[peterseager]

Can I please add a rider to this question because it lines up with work I am doing to get the Simplex Hydro lubricator going. For those of you with cylinder presure gauges what cylinder presures do you see under typical running conditions?

Peter

[wiltsrob]

morning..

To the best of my knowledge the cylinder pressure can reach as much as 90% of boiler pressure but most of the time will be at about 60% max as we never really load the train up or run at full regulator and so on...it has been a while since I ran a loco with gauges on..

to test a mechanical one .. place your finger over the end of the pipe and turn the ratchet.. you should NOT be able to hold back the oil .. if you can then it needs looking at..

Robert

[runner42]

Thanks Robert, can't be any simpler than that. Would engine oil suffice for the test?

Brian

[wiltsrob]

no.. you need to use the oil you are going to be using normally... engine oil is far to thin...

I use 460 grade steam oil ...I found this to be best..

Robert

[albert]

Hello,
Engine oil is OK--if it will hold pressure with thin oil it will be better still with thick oil.
Albert

Looking at more replies the engine oil is ONLY for test purposes

[Deleted]

Depends what you mean by "Engine Oil" ??-------- Def. NOT what goes in your car....If you're trying to replicate actual running conditions then why not do as WILTSROB suggests and use the oil that's going to be in there anyway Surely that's the whole point ??---------I would suggest a "Protected" finger is more appropriate as it's quite easy to inject a small quantity of oil into the skin if your'e not careful !!........As a Model Engineer why not construct a simple test rig with a view area, a connector for your air compressor and a screw-in point for the oil check valve ??.............. a piece of thick-wall, circular bronze/steel/iron ( say 2" dia ??)would do it with a blanking plate at one end and some "Thick" ( 6mm ) perspex at the other........ Don't forget to "prime" the whole system first ie}-- purge the air out.EDIT}--- Forgot to say generally a rule-of-thumb for cyl. press. might be 75% at full cut-off....Why not add a cylinder chest pressure gauge anyway ??........certainly will give a bit more "Technical" look to your backhead !!

[GWR 101]

Being a novice at this can I quote LBSC, " The lubricator can now be tested by putting some oil - automobile oil will do- in the tank and turning the ratchet wheel clockwise with your fingers. A distinct resistance should be felt as the ram takes the downward stroke and the oil forces the clack balls off their seating's. Put your thumb over each outlet in turn; and if the lubricator is OK no matter if you are as strong as Samson you won't be able to prevent the oil coming out .......... These weeny lubricators have been tested to pump against 450lb pressure." M.Evans quotes delivery pressure of 400 to 500 lbs/sq inch. Hope this helps, not wanting to complicate Alans question but I would have thought volume flow would also be a consideration regarding the number of points being lubricated. Paul

[Deleted]

Hi Brian,

A good mechanical lubricator will pump 200psi or more but you may be limited on yours by the spring pressure holding the oscillating cylinder onto the port face, You can test by attaching a pressure gauge to the outlet but be careful not to damage the gauge! Remember that even thick steam oil goes thin when the lubricator gets hot (and it probably will!) so testing with a thinner oil will give truer results.

My brother's 5" loco has pressure gauges on the steamchests and they rarely get above 20psi under normal running. They will get up to 40psi when the loco is pulling hard though with the regulator fully open. The working pressure is 80psi so it's possible the regulator or pipework is restricting the steam flow. The gauges do pulse even though they are connected to the steam pipes before they enter the steamchests. I would have expected the gauges to read higher as Robert suggests.

John

[Deleted]

Hello again---- As it's a proven design down the years I don't think you'll have any problems with its' performance..As BAGGO pointed out if it's location is such that it gets hot then yes, the oil will thin out before it gets to the pump...My Simplex and Polly 2 have their pumps mounted on the running boards alongside the smokebox and the oil seems to stay quite viscous in this position...

[jma1009]

a few points arise from all the above very good advice...

1. always test these things before fitting them including the spring loaded check valve
the slightest error in drilling the ports on the oscillating cylinder etc will reduce its effectiveness.

2. there is no point having a spring loaded check valve with a spring that exerts a pressure greater than the working pressure of the loco otherwise you are just straining the pump. ive checked quite a few commercial ones and the springs all exerted far more force than necessary. the seal of the check valve must be absolutely perfect. you can pump oil into your pressure gauges if you want to, but mine will only ever get used for steam or water!

cheers,
julian

[albert]

Hello,
I use a modified tubeless tyre valve as an inline check valve in my oil line,the main mod is to shorten the spring so it just holds the valve on its seat.
Albert

[runner42]

Thanks for all your replies, I'll digest these more fully later as I have failed the simple test. I need to modify my initial statement that I built it to LBSC's instructions, viz I didn't have all the data necessary to build it. The initial sketch I had was as produced above, which is only an outline sketch, nothing on the inner workings. I solicited more details on the construction via the internet and received the below drawing. It was almost complete but like many LBSC's output rely on details being provided in the narratives that accompanied it, which I didn't get. But alas beggars can't be choosers.
The spring sizes for example was a guess and maybe overspecified in one instance and underspecified in the other. 

PS Is that an oil check valve integrated in the mechanical lubricator, because LBSC also specifies a check valve remote from the lubricator at the junction of the inputs to the cylinders?

Regards Brian.

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[jma1009]

hi brian,
there is no need for anymore than one check valve below the lubricator.
cheers,
julian

[GWR 101]

I understand that LBSC approach was to provide "words" to go with his designs. I see that the drawing you show above is as shown in his book Shop Shed and Road, if its any help after a quick read through he mentions making a spring of 24 gauge hard brass wire wound round a piece of 3/32 silver steel, so this may give you some idea of the size of spring required. He does comment that its fitted to a 2-4-0 engine of 3.5 gauge and if its any consolation he does make reference to forcing oil past two check valves, however I am not in a position to know why he proposed two so I will leave you to follow advice from more knowledgeable sources. Paul

[GWR 101]

Hi just to come back on this I decided to see if Martin Evans was any more precise in his "Manual of Model Steam Locomotive Construction" and he refers to a 32 gauge spring. Incidentally in reading this he refers to two check valves the other one being on the steam pipe or steam chest, and states it is a good plan to have a slightly stronger spring on the one on the lubricator. Hope this is of some help, I am only just reaching this part of the build on my first loco so it is of interest to me also, and as previously stated there are plenty more knowledgeable than me out there. Paul

[jma1009]

paul,
all you need to do is have a check valve on the lubricator with a spring no more no less than than the working pressure of the loco. use a pinch of salt with much of what martin evans wrote in his book - he copied lots of other stuff and was pretty 'green' in those days! it stands to reason that if the check valve on the lubricator works ok there is no need for a second check valve. same as there is no need for 2 check valves on the delivery side of an injector, or a hand pump, or axle pump.
cheers,
julian

[runner42]

Thanks Paul and Julian. So the oil check valve is intergrated in the mechanical lubricator. It appears that I have a too strong a spring in this valve. Does the simple test apply equally after the oil check valve? Indications are that it does to force open another check valve downstream and then oppose the steam pressure to get it into the cylinders. Providing 200psi output as Baggo states is REALLY necessary. All this from an 1/8th" dia bore and a 1/4" stroke! 

As an asside I have purchased a mechanical lubricator from a UK source. It has tank size of 2" x 1 5/8ths" x 1 3/4", far too big. I was debating whether or not to use it by cutting the tank down to nearer the specified size. However, the height is of major concern, since it is predicated on the below tank measurement, which has a straight down oil pipe connection instead of an elbow, which requires further intrusion into the space above the front bogie and at the top of the tank by the cam at TDC being just below the rim.

Regards Brian

  
 

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[wiltsrob]

Brian.

I have 2 of these lubricators on the A4 ( 1 single ram 1 a twin ) they work really well ..BUT .. you have to adjust them as per the sheet that comes with them first..

Robert

[ejparrott]

If space is an issue, horizontal pumps can be employed instead, as long as the suction point is low enough. Scotch crank designs are better than oscillating in this instance, as they take up less room to operate.