|
Post by Deleted on Oct 2, 2014 14:16:00 GMT
On a true hydrostatic system the oil is blown down the pipe by steam from the jockey valve. Peter ---------------------------- so what are the TWO condensing coils for then ?? The coils are to condense the steam supply to the oil tank so that only water reaches the tank. Out of curiousity, where were the oil tanks situated? Under the cab floor? John
|
|
|
Post by Deleted on Oct 2, 2014 14:25:32 GMT
No----in the lubricator body itself--------
|
|
|
Post by Deleted on Oct 2, 2014 15:48:06 GMT
All joking aside, on the western lubie systems I have come across so far (excluding the Dukedog) the 2 separate coils are indeed that, separate, the cock on top of the lubie at the end of the pipes from the coils decides which is used
|
|
|
Post by Deleted on Oct 2, 2014 16:05:15 GMT
The GWR NEVER makes jokes about railway Engineering, good Sir !! ( We let others do that.....).... Sometimes we supply "Solutions" to a problem the owners didn't know they had...Indeed, this "Western Streak" railtour that I'm going on shortly is almost a form of the Exchange Trials in a way and I'm eager to see "our" centre big-end in action ( That's put the mokers on it for sure now !!)........I made several new coil assemblies whilst contracting at Bridgenorth MPD ( Including the 3-piece bracket that has a support piece for every turn of the tube....I believe that valve is referred to as the J-valve or the 3-way valve ?? --- and indeed does select either one or the other coil...(In todays terminology it's called a "Redundant System" in case of failure of the first one.....Common practice in Automotive brakes or Aircraft control systems nowadays, I believe ??.........................................
|
|
|
Post by Deleted on Oct 2, 2014 18:22:28 GMT
There we go, straight from the horses mouth! I always thought the J valve was the one attached to the regulator linkage, J being short for jockey? Live and learn!
|
|
|
Post by Deleted on Oct 2, 2014 18:30:56 GMT
I think I'm more of a Donkey !!
|
|
jma1009
Elder Statesman
Posts: 5,901
|
Post by jma1009 on Oct 2, 2014 22:28:37 GMT
hi ben, you are quite correct as the jockey valve is actuated by the regulator quadrant linkeage. in fullsize there is no atomising unless the regulator is moved off the closed position. in miniature there is no need for the atomising part of the jockey valve, or for that matter any need for the Cottam/Evans check valve on the bottom of the sight feed. this considerably simplifies the well known Cottam/Evans design as per 'Torquay Manor' etc. cheers, julian
|
|
|
Post by Deleted on Oct 2, 2014 23:31:21 GMT
Yes, I know the JOCKEY valve by that name and in that function as well--------It's just I had a part-memory that the condensing coils selector valve was either called the 3-way valve OR the J-valve because of it's shape........An atomising valve within the Jockey valve ??......I thought they were at the other end ie at the delivery end, (after the choke-)-where the oil is about to be fed into the cylinders.........JULIAN, here is a typical GWR footplate view .. Could you talk us through the various pipes involved with the Hydrostatic system as I'm beginning to think I've been labouring under a misapprehension all these recent years regarding what's actually happening........I see the condensing coils and the two pipes leading down to the main body.....the condensate water displaces the oil which moves up from the lower gallery--controlled by the screw adjusters----through the water in the glass tube, to the upper gallery....but then what ?? How does the jockey valve ( which I thought only had oil within it ) fit into the system then ??>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
|
|
|
Post by Deleted on Oct 3, 2014 0:03:28 GMT
After some research, I think it might have been the "W" valve that I had in mind ?? ---------
|
|
jma1009
Elder Statesman
Posts: 5,901
|
Post by jma1009 on Oct 3, 2014 0:53:05 GMT
hi alan,
on the GWR arrangement the condensing coils lead to the body containing the oil behind the sight feeds - in miniature they go to the bottom of the displacement tank hidden under the footplate as if scale the 'body' is too small for practical purposes in our sizes.
the feed is regulated by the needle valves on the bottom of the sight feeds same as in miniature, except that if properly designed in miniature regulation is also controlled by the size of pipes and jet at the base of the sight glasses.
in miniature the roy amesbury arrangement which i use has the sight glass AFTER the valve actuated by the regulator quadrant (in fullsize the 'jockey' valve).
note that in fullsize one of the feeds from the jockey valve actually leads direct to the Churchward smokebox regulator - one of the reasons why GWR locos were much easier to drive.
in your above pic some of the pipework is missing on the jockey valve which is a bit disconcerting as the loco is in steam with a fire!
there is an extra steam feed into the jockey valve in fullsize which is opened when the regulator is opened that mixes with the oil from the sight glasses and 'atomises' same on its way to the cylinders. the jockey valve also acts as an on/off valve for the oil for the cylinders being open when the regulator is open, there being a clever part of the quadrant so that the valve opens when the loco is coasting before the regulator is properly open. as previously stated many times the atomising part isnt necessary in miniature - after all no mechanical lubricator has an atomising extra steam feed!
i hope the above description is of help. ive got the original GWR instructions and drawings and will happily post same but i dont think they add much to our miniature versions and probably overly complicate matters! (they confused Fred Cottam and lead to him overly complicating his design which was copied by martin evans)
cheers, julian
|
|
|
Post by Deleted on Oct 3, 2014 1:43:13 GMT
Hi Julian and thanks for that comprehensive reply....Most of that I'm glad to say I'd remembered correctly ( The cranked link, coasting, oil to the regulator, oil to the valve spindles, etc)....It's this business of the jockey valve opening both steam and oil into the line to the cylinders and atomising it BEFORE the oil has even left the backhead vicinity......Does that mean then that the two pipes (L/H and R/H ) that go from the Jockey valve to the cylinders are carrying atomised oil as opposed to normal oil ??.........I was under the impression that it was straight oil from the reservoir---via the jockey---down to the restrictor---then into the cylinders via an atomiser at the last moment............................................................................................... In this photo is that smaller joining union on the R/H side the steam supply then ?? ---------If so then where is it tapped into---the steam fountain I presume ??----------------------------------------------------------
|
|
|
Post by Deleted on Oct 3, 2014 1:52:57 GMT
This is going to be fun when I look in detail at the Hydrostatic set-up on The Bear as it'll pre-date the later Churchward types........Might be more in keeping with the Dean Goods style maybe ??
|
|
|
Post by peterseager on Oct 3, 2014 7:05:15 GMT
On a true hydrostatic system the oil is blown down the pipe by steam from the jockey valve. Peter ---------------------------- so what are the TWO condensing coils for then ?? Only one condesing coil is used at a time as was pointed out above. The condensing coil takes steam from the manifold and feeds condensed steam, ie water, into the bottom of the lubricator. The oil leaving the lubricator meets the supply of steam from the jockey valve so there is no actual steam presure forcing the oil out. It is all about the presure due to a column of water and a column of oil being different, so forcing the oil out to be displaced by water and independent of boiler and cylinder pressure. Hence the term hydrostatic. A choke is placed at the end of the pipe conducting oil to the cylinders. This limits the amount of steam that can flow down the pipe and so maintains boiler pressure at the lubricator. Peter
|
|
JDEng
Part of the e-furniture
Posts: 384
|
Post by JDEng on Oct 3, 2014 8:05:46 GMT
There's a few points raised over the last few days that I wanted to reply to but have been a bit busy.
Julian: I accept what you say about mechanical lubrication on the GWR Castles regarding superheat but I don't follow your argument totally. I personally can't see the degree of superheat making any difference to the successs or otherwise of a lubrication system. I accept that different oils are used depending on the degree of superheat but the lubricator is just a means of supply; unless I'm missing something, the thickness of the oil won't make any difference to the operation of the lubricator and it thins once it's warm anyway. The King Arthurs had hydrostatic lubrication, as did some of the LNER A1's (including 4472 by the way) and I would be interested to know how their level of superheat compared with a Castle - I suspect it may have been higher but am prepared to be corrected.
Regarding mechanical lubricators and steam atomisation - I think you'll find that a lot of mechanical lubrication systems for cylinders and valves were fitted with atomisers. The valve was usually connected to the drain cocks so that the atomisers were turned off when the taps were open; the idea being to provide a proper mist of oil to the various working parts.
I think, at the end of the day, that the use of a hydrostatic/displacement type of lubricator or a mechanical one is largely a matter of personal preference. Both types were used extensively in full size and both offer certain advantages and disadvantages. Personally, I prefer a mechanical system BUT I don't have a problem with hydrostatic and wouldn't rule out fitting one.
As I said in a previous post, the problem with miniature mechanical lubricators is that they are relatively crude and cannot offer the fine control that a hydrostatic system can. Driver's can see how much oil a hydrostatic is delivering but a mechanical is a bit of a mystery so they tend to "crank it up - just to be safe". A well made, accurate mechanical lubricator would be just as efficient as a hydrostatic/displacement.
To accurately control the flow from a mechanical you need to be able to adjust the stroke of each pump individually. The bore needs to be relatively small. You don't need seals, you're only pumping to around 100psi, a full size Wakefield doesn't have seals and they're tested to somewhere around 1000psi. I don't think you need a delivery sight glass, the ones you see in full size tend to be on industrial or narrow gauge locos or stationary engines; main-line locomotives didn't have them, presumably because they're too likely to get broken and cause the loco to "fail" - you can't see them when the engines running anyway because the lubricators usually outside on the running plate. Ideally the pump rams and the bores are lapped together to give a perfect joint - something that should be well within the capability of someone like Roger with his precision background and range of equipment. The pumps work in an oil bath so wear will be at a minimum.
Just a few thoughts to chuck into the 'pot. At the ned of the day, I think, like many things, it's largely a matter of taste.
Kind regards,
John.
|
|
|
Post by Roger on Oct 3, 2014 8:18:44 GMT
That's very interesting John, and it sounds like a balanced and fair assessment of what's required on a model. I think the key thing you've highlighted is that a less crude mechanical pump arrangement could be made that would result in better control of the delivery. Do you think a long delivery pipe back to the cab for a sight glass would be an issue, would the pump need to go at the back to shorten the pipe run? My instinct says not. After all, the hydrostatic ones feed half that distance without any issues. It's only a small amount so the flow is small. The tubes could always be made a little larger if necessary.
|
|
|
Post by Deleted on Oct 3, 2014 8:26:53 GMT
Hi PETE----I shouldn't have put the word TWO into that sentence.....I was actually questioning the need for the coils per sey if the oil was being "blown down the pipe by steam from the Jockey valve"---something I hadn't appreciated right from the word go and I have been labouring under that mis-apprehension ever since......I knew the jockey valve controlled the "on-off" function but I thought it was oil-only being passed along to the cylinders ---with an atomiser at each point of delivery----Hence my question a while back about how did they initially fill the delivery pipe when the loco was new/been overhauled.... My apologies to those that I may have inadvertently mis-lead....My brain's RAM faculty has diminished somewhat down the years...........and I don't have the luxury of any printed matter to refer to ( Can someone E-mail me the actual GWR instructions ??....There is precious little in the Black Book and --- very surprisingly----NOTHING at all in E J Nutty's Blue book !!)...........Yes people, it really IS worth being on this forum.... Dr.s'---- Emmas' come what may !!
|
|
JDEng
Part of the e-furniture
Posts: 384
|
Post by JDEng on Oct 3, 2014 8:54:48 GMT
That's very interesting John, and it sounds like a balanced and fair assessment of what's required on a model. I think the key thing you've highlighted is that a less crude mechanical pump arrangement could be made that would result in better control of the delivery. Do you think a long delivery pipe back to the cab for a sight glass would be an issue, would the pump need to go at the back to shorten the pipe run? My instinct says not. After all, the hydrostatic ones feed half that distance without any issues. It's only a small amount so the flow is small. The tubes could always be made a little larger if necessary. Roger, I think the length of the pipe run doesn't really matter, what goes in at one end will come out at the other regardless of diameter because it's being pumped. I can't really see the point in making a run all the way back to the cab in order to put a sight glass in, it does seem toi be over complicating things to me but I can understand your concerns about knowing the system is working. You will need a non-return valve at the point of delivery from the pump into the pipe, you will need a second non-return valve at the point where the pipe delivers into the steam chest or main steam pipe - this prevents any back pressure forcing the oil backwards and also keeps the pipes full whilst the loco is standing for any length of time. A lot of full size systems have a bleed valve incorporated in the non-return valve on the main steam pipe/steam chest; if you include a "flushing wheel" in the design of the ratchet you can then spin the lubricator over with the bleed open to check the line is full and that the pump is delivering - the oil takes the easier route to atmosphere (which is why you shouldn't use a by-pass in this application by the way). Whether it is practical to do this in reality will depend on what room you have available and how good the access is of course. I don't think I'd worry too much about two pumps as you suggested in a previous post. Silvertown lubricators were double acting and the LMS used them on cylinders but the LNER were happy with single acting Wakefields in the same application. In an ideal situation you would have a pump for each cylinder though, then you can be sure that they are both getting the right amount of oil. J.
|
|
|
Post by Deleted on Oct 3, 2014 9:01:16 GMT
I have just found a set of cab pics I took a few weeks ago for a mate who is building a Dukedog in 5 inch. So can briefly describe the system on that. There is one steam cock on the left of the regulator housing, this feeds the jockey valve and condenser (only one of them!) There is another cock on top of the lubie itself which isolates the incoming water from the condenser (this must be off for filling purposes as it may be condensate in there but it is at boiler pressure and won't be condensate for long when the filler cap is removed!) The lubie has 3 other cocks on it, 1 underneath the sight glass which adjusts your feed rate another right at the bottom of the lubie which drains the condensate out to allow filling up again with oil and the last is a bypass which is normally off, it's located above the sight glass, this does the same job as the feed rate one but only if the glass breaks! The oil then departs the lubie via the pipe at the top left to the jockey valve where it is atomised (only when the regulator it set to make it do so) and sent on its merry way to the cylinders. As a point of interest, the regulator has a separate displacement lubie of its own situated on top of the dome. Hope this is of interest! Cheers Ben
|
|
|
Post by Deleted on Oct 3, 2014 9:09:06 GMT
Oh there is also a warming system, there is a cock on the right of the regulator housing, this feeds a pipe which disappears into the body of the lubie, coils around inside a few times and then pops back out and exhausts into the lubie drain pipe. The cock was only just cracked so steam was just exhausting from the drain, this was enough to warm the oil nicely and thin it from its normal gloopy self!
|
|
|
Post by Roger on Oct 3, 2014 9:16:13 GMT
Thanks for posting those Ben, that's really useful.
|
|