|
Post by peterseager on Feb 19, 2012 10:23:09 GMT
Ian
The steam is taken from the boiler.
Basil touches on this point in his article. He puts the oil tank under the footplate and arranges the rest high in the cab looking like a complete Detroit lubricator.
Basil also has chokes where the oil pipes meet the steam pipes going into the cylinder.
Peter
|
|
jma1009
Elder Statesman
Posts: 5,901
|
Post by jma1009 on Feb 19, 2012 12:25:49 GMT
peter, thank you for your very helpful posts re basil palmer. saved me trawling through through my old MEs to find the exact date of basil's article cheers, julian
|
|
|
Post by fostergp6nhp on Feb 19, 2012 20:58:33 GMT
On GWR the ........ steam supply to the resevoir via the condensing coil is controled by the valve under the regulator handle which is also the atomiser(choke) Not so, the steam supply to the condenser coil comes directly from the fountain on top of the boiler. Sorry! Correct, what threw me without checking is that the valve under the regulator has 2 live feeds in to it.
|
|
jma1009
Elder Statesman
Posts: 5,901
|
Post by jma1009 on Feb 19, 2012 22:06:42 GMT
i have got a copy of GWR circular 5801 issued to footplate crews showing how the 4 sizes of GWR sight feed lubricators work with drawings of the sight feeds and regulator valves and all the pipework, and the smokebox arrangements, if any one is interested. unfortunately i havent got a scanner
|
|
|
Post by fostergp6nhp on Feb 20, 2012 20:14:59 GMT
Is this any help? Attachments:
|
|
jch
Member
Posts: 4
|
Post by jch on Mar 7, 2022 18:58:36 GMT
Good evening, I have been following this discussion with interest as I am planning to use hydrostatic lubrication on my large scale 7.25" engine . Most of the comments refer to 5" engines. I have been pondering over such things as pipe size, nozzle and needle valve size. Also, why should there be a need for a choke at the steam chest end of the delivery pipe. Any suggestions would be appreciated. BTW the cylinders are 3.5" X 4.25" Cheers, John.
|
|
mbrown
Elder Statesman
Posts: 1,720
|
Post by mbrown on Mar 7, 2022 21:25:54 GMT
Interesting questions.
Others may disagree, but my own view is that a hydrostatic system as used for 5" g would be fine for 7.25"g. We tend to over oil our locos and it is surprising how little a standard gauge loco uses in comparison. A bigger loco won't need a proportionate increase in the amount of oil. The systems like those designed by Don Young are partially self-regulating. If you open the control valve too much the oil builds back in the glass. For a larger loco, you can just let the drops form a little more rapidly than for a smaller loco.
The choke at the cylinder end is part of that self regulation. With the regulator open, there is a pressure drop between the oil tank at boiler pressure and the steam chest which feeds the oil through. But when the regulator is closed, the steamchest pressure drops to almost zero and the choke prevents the pressure in the oil tank forcing all the oil through in one gulp.
Hope that is helpful.
Malcolm.
|
|
|
Post by davewoo on Mar 8, 2022 13:28:23 GMT
I'd agree with Malcolm, When I made a hydrostatic system for my Rob Roy years ago, I made another for my Simplex (waiting to be fitted since 1993!)a friends Simplex and a twin sight glass system for a 71/4" Black Five (Highlander?). The one for Highlander had exactly the same size jet as the others drilled No 78, I think the regulating valve spindle is 7BA with a long taper and with a 1mm drilled choke as the oil feed entered each steam chest. It ran fine for many years, I saw it for sale at an auction long after the original owners death, still fitted with the same arrangement. The dimensions are all available, there are some drawings and a very well written article posted on here by Julian (jma 1009), the dimensions and system are exactly as I used. Little engines use very little oil Rob Roy's tank is only about 5/8" dia and less than 2" long, hidden behind the cab steps, and that lasts seemingly forever, my bum gives out before the oil! I always use Glycerine in the sight glass, I tried brine at first but found the sight glass goes cloudy and difficult to see through quite quickly. Dave Do check on jet sizes if you buy a commercially made sight glass, some have a much to large jet size, and a short taper on the regulating valve, not sure from which supplier.
Just remembered I made some single sight glasses and one ended up on a 71/4" Jessie, I know the builder was happy with it as he had had problems with the mechanical one. One thing I wouldn't do again is that R-R has a small screw on cap on the bottom of the oil tank to drain the water out, this has proved a bit of a faff. A drain valve is a much better idea, The bigger you can make the filler cap the better, mines a bit small and steam oil is very thick.
|
|
|
Post by andyhigham on Mar 8, 2022 15:58:02 GMT
First time out with Alice Nutter, the steam oil wouldn't pour into the tank, I ended up putting my steam oil bottle in a bucket of hot water to heat it up. Next time out I filled a cheap pump action oil can, it works a treat
|
|
jch
Member
Posts: 4
|
Post by jch on Mar 9, 2022 14:19:19 GMT
Thanks for your advice regarding these lubricators.......makes sense really....bigger cylinders, more oil. As you say just increase the flow of drops. Regarding the choke it's much as I thought but wasn't sure. There has to be a drop in pressure in the system (steam chest end) to draw the oil down. Next step is buy a pack of 78 drills! Bound to break a few Thanks again, John
|
|
jch
Member
Posts: 4
|
Post by jch on Mar 9, 2022 14:35:24 GMT
Just another thought on the hydrostatic lube, why is it that in miniature scales the oil tank is as low as possible when on a full size western engine it is right under the jets? John
|
|
mbrown
Elder Statesman
Posts: 1,720
|
Post by mbrown on Mar 9, 2022 15:14:30 GMT
The oil tank for models is usually a lot bigger than scale size - oil drops don't scale down in proportion which is one reason we use a disproportionate amount of oil. So a big tank needs to go somewhere inconspicuous and low down offers more possibilities. On my LYN, the tank is under the driver's seat and on the Burma Mines loco it is in a cab side locker invented for the purpose.
The tank also needs to be kept cool so that the steam evaporates. On full size locos, the hydrostatic lubricator was often on the side of the cab at about eye level for convenience. The GWR position close to the firebox door would be cool enough at 12" to the foot but not in our scales because of the conductivity across smaller distances.
Malcolm
|
|
baldric
E-xcellent poster
Posts: 208
|
Post by baldric on Mar 9, 2022 18:58:42 GMT
Don't forget on GWR locos there is a separate condenser, away from the fire, in the roof, the amount of steam used is so low there is plenty of time for it to condense.
Baldric.
|
|
jch
Member
Posts: 4
|
Post by jch on May 2, 2022 19:51:42 GMT
C
|
|
|
Post by davewoo on May 3, 2022 9:45:39 GMT
I've seen a loco, I think it was a Butch or Ajax, fitted with an oil tank very close to the boiler and the builder found that it originally would not condense properly, he cleverly made a spiral copper condensing tube like a spring and soldered it to the back of the cab steps to act as a heat sink, obviously outside the frames and in relatively cool air. It seemed to work perfectly and had been in use for some years, so it seems as long as there is somewhere for the steam to condense the oil tank can be somewhere quite warm. An added advantage is de icing of the cab steps on a frosty morning!
Dave
|
|
|
Post by andyhigham on May 3, 2022 14:00:53 GMT
|
|