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Post by suctionhose on Jan 4, 2019 12:01:17 GMT
I haven't tolerated over oiling or under oiling for that matter in any of my engines. I suspect that an oily wet chimney is over oiling but at least it is an indicator. My loco had a twin mechanical lubricator for 15 years and the change to hydrostatic was with no net change. It was just a curiosity and for something else to look at.
When they are going well they are trouble free. Problems I've had are changes from summer to winter - feed adjustment - and oil going sideways onto the glass which happened once while I left it running as I waited in the slope down to ground off the turntable. In reality, what goes in must come out and even if the droplet is not forming visibly in the glass then it is probably still working. You can't see it though.
Generally the system is very reliable.
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Post by terrier060 on Jan 8, 2019 12:27:06 GMT
OK, thanks to Julian I have now been introduced to later hydrostatic lubricator designs. I have to say though that they are more or less direct cribs from the Fred Cottam design, but missing the all-important atomising valve. There are minor differences in the design of the sight feed with the introduction of 'O' rings.
The atomising valve has a very important function besides atomising the steam (though I am aware of comments stating this does not work - though with no proof), particularly if you are building a GWR loco, in that it keeps the oil flowing while coasting and shuts it off when stationary as do the full-size.
The only advantage that these later designs have over the Cottam one is they dispense with this all-important feature. The quadrant adds more detail to the back head.
I have used the Cottam design for years with no problems. The only variation is that Bill and I used salt water in the sight feed. I have never tried glycerine, but would be happy to give it a try.
I am now trying to think of ways to hide the sight feed on the Terrier, which of course had what I assume was a displacement lubricator mounted on the smokebox and tallow cups.
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Post by Roger on Jan 8, 2019 13:04:34 GMT
OK, thanks to Julian I have now been introduced to later hydrostatic lubricator designs. I have to say though that they are more or less direct cribs from the Fred Cottam design, but missing the all-important atomising valve. There are minor differences in the design of the sight feed with the introduction of 'O' rings. The atomising valve has a very important function besides atomising the steam (though I am aware of comments stating this does not work - though with no proof), particularly if you are building a GWR loco, in that it keeps the oil flowing while coasting and shuts it off when stationary as do the full-size. The only advantage that these later designs have over the Cottam one is they dispense with this all-important feature. The quadrant adds more detail to the back head. I have used the Cottam design for years with no problems. The only variation is that Bill and I used salt water in the sight feed. I have never tried glycerine, but would be happy to give it a try. I am now trying to think of ways to hide the sight feed on the Terrier, which of course had what I assume was a displacement lubricator mounted on the smokebox and tallow cups. I'm not sure how you can hide the sight feed since you need to see it. Of course, you could always change your mind and use a mechanical lubricator which wouldn't need to be seen.
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Post by terrier060 on Jan 8, 2019 13:58:39 GMT
Hi Roger - I may just stick with a simple displacement lubricator - no site feed, and rely on the amount of oil used at the end of the run. After all I have no superheaters so am using wet steam. I don't like mechanical pumps - besides all the moving parts I would have to have a rod from some part of the motion which would be incorrect.
The displacement lubricator would only work when the regulator was open so in effect would replace the atomising valve.
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Jan 8, 2019 19:52:58 GMT
Hi Ed,
The devil is in the detail!
I have stated this all before on other threads, but the Cottam design is a very poor design. (It was copied by Martin Evans for Torquay Manor so you don't have to go back to the late 1940s!)
It has 2 check valves that are totally superfluous, and a 1/32" hole through the jet at the bottom of the sight feed which is way too big.
Anyway, your A1X Terrier had a sight feed in the cab, so the only question is the issue of a sight feed in the cab of the your also original A1 type!
I don't think on your A1 Terrier you should rely on simple displacement lubricators on a 7.25"g loco. (I know Shawki is an advocate of them).
If you don't want a sight feed in the A1 cab, then fit a hidden mechanical lubricator such as Roger has done. Personally, I wouldn't give a jot if an A1 Terrier had a non-prototypical sight feed in the cab for the oil feed.
The turret/manifold or steam pipe to the displacement oil tank can have an on/off screw down valve to use when the loco is at a station/stationary to save upsetting the setting of the needle valve on the base of the sight feed glass.
Cheers,
Julian
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mbrown
Elder Statesman
Posts: 1,724
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Post by mbrown on Jan 8, 2019 20:14:34 GMT
The sight feed fitting I made for the BMR loco has a shut off valve for the steam to the oil tank at the top (but it could just as well be on the manifold or elsewhere) and a stop valve where the oil rises from the tank to the sight glasses and before it gets to the regulating needle valves. You could use either to stop the oil flow when stationary, leaving the needle valves well alone - but I reckon the shut off just below the sight glasses is a more positive control. Malcolm Detroit lubricator by malcolm brown, on
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Post by suctionhose on Jan 9, 2019 2:01:46 GMT
what a beauty! how big is that?
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mbrown
Elder Statesman
Posts: 1,724
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Post by mbrown on Jan 9, 2019 7:32:36 GMT
Just over an inch wide. The small handwheels are from 1/4" hex brass. The glasses inside are standard ones from the trade - either 7/16" or 1/2" (can't remember which).
It's now on the loco and has worked fine for several steamings. The trickiest bit is setting the needle valves to get a nice slowly-forming blob of oil. The valves have a pretty fine taper but it's still very sensitive and you only need the valves barely cracked. That's why the main shut off (with the handle) helps as you can leave the needle valves as set but stop the oil flow temporarily.
Malcolm
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Post by terrier060 on Jan 9, 2019 10:54:32 GMT
Very nice Malcolm - really looks the part. I will have further thoughts about lubrication. Our launch engine which is a compound and is superheated relies on a displacement lubricator which seems to work fine. And so simple. I agree about a handy stop valve, but it would be nice to have it automatically connected to the regulator. Maybe I could do something in the smokebox. I am still a fan of Cottam though and certainly disagree that it is a poor design - quite the contrary. Has worked years for me with no trouble.
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Post by terrier060 on Jan 9, 2019 12:46:33 GMT
PS. My version by Cottam says nothing about two check valves. I have non on my setup. I do have an extra live steam shut-off valve though. One for the atomiser and one for the oil tank, for filling with pressure in the boiler. I have never had to use it because even with a long afternoon run the tank has never been more than a third empty. I suspect that a snifting valve is essential - certainly I have one, because otherwise back-pressure could be a problem.
PPS. Out of interest I have just taken the sight feed to pieces as I made some 50 years ago. I have made several modifications. The nipple from which the oil droplet forms has a No 80 hole through the middle and is filed to a knife edge (my eyes must have been a lot sharper in those days!). It is long as Cottam suggests - about 3/16". I have used 1/2" diameter Pyrex glass rather than 5/8" diameter as specified and four rather than three rods securing the top and bottom fitting. If I were making it today I would make the nipple removable and use 'O' rings rather than the Hallite gasket. The one on my 'Princess' is smaller and has a brass tube holding the top and bottom together, with a window to observe the droplet through. There is no atomising valve and the driver has to manually turn it on and off.
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jma1009
Elder Statesman
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Post by jma1009 on Jan 9, 2019 21:35:44 GMT
Hi Ed,
As you know, my own view is that the atomising valve is also unnecessary in miniature. I have the fullsize GWR drawings for same. (I also have a number of drawings of Fred Cottam, via a very old late friend of mine, Dennis Hunt, who was a fellow member of the Harrow club and a friend of Fred's and they were of similar age).
Roy Amesbury completely dispensed with the atomising valve on his 5"g GWR 'President' design and won IMLEC twice. Roy was a highly accomplished engineer both in fullsize at Rolls Royce, and in miniature. From what I remember of Fred Cottam, he was dining car attendant on the railways.
An on/off valve of the steam supply to the displacement oil tank, whether actuated as per GWR via a quadrant on the regulator, or manually operated, is required/desirable.
If your 50 year old sight feed you refer to has a No.80 hole through the jet, it is clearly NOT made to the Cottam drawings which show a No.55 (52 thou dia hole) through the jet! The Torquay Manor drawings show a 1/32" hole through the jet! The Torquay Manor drawings show 2 check valves.
You can actually go down to a 5/16" dia glass of say a pyrex test tube for the sight glass if you felt so inclined.
Cheers,
Julian
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Post by Jim Scott on Jan 9, 2019 22:46:30 GMT
..... I have been thinking of having the whole roof removable for driving, but the convenient join down the centre could be an advantage. I shall have to think about it. Seeing yours with the roof removed may help me decide. Hi Ed Regarding your roof, I think it might be possible to leave it in place in 7 1/4" gauge. It will depend how close to the roof your boiler fittings are and whether you can reach them easily. If not, the riveted strap (yet to be fitted ) at the midway point is an ideal break point for a removable rear half.
However the spectacle plate will have to be at least partly removable for firing purposes, the most convenient point to make the joint is not too far above the rear cab boxes. You can probably work out where the firehole should be on the photos even though the boiler isn't fitted at the moment.
The following photos are from the drivers viewpoint. Apologies for the distorted images, due to a close-up lens and having no wiggle room to get behind the camera..!
Jim
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Post by terrier060 on Jan 9, 2019 23:49:22 GMT
Thanks for that Jim. My rear spectacle plate will be split about the same place as yours. On Fenchurch there is a second plate at the front of the bunker. I suspect it is not original but there to stiffen the back of the cab after many years of coal being thrown in. Fenchurch has already had several roofs and I suspect most of the Terriers by now have had most of their steel sheets replaced as they rusted through.
I am making a start at cutting out the two cabs as soon as Jan and I get rid of this virus, which is very persistent and will not go away. Not quite flu but just as debilitating. Then I shall have a chance to see how much I need to remove to drive them comfortably.
Very nice work by=the-way.
Ed
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Post by terrier060 on Jan 10, 2019 13:31:50 GMT
PS. One thing that I cannot quite understand - I see you have used the correct eight screws to hold the glass in. On Fenchurch they are fixed in exactly the same way by eight screws on both the inside and the outside of the cab. This must mean they share the same holes in the spectacle plate. I find it hard to believe there is enough thread in the thin steel plate for the screws in both bezels?? What do you think. My sheets work out at 36 thou thick.
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Jan 10, 2019 14:58:55 GMT
PS. One thing that I cannot quite understand - I see you have used the correct eight screws to hold the glass in. On Fenchurch they are fixed in exactly the same way by eight screws on both the inside and the outside of the cab. This must mean they share the same holes in the spectacle plate. I find it hard to believe there is enough thread in the thin steel plate for the screws in both bezels?? What do you think. My sheets work out at 36 thou thick. Possibly they are 'screw into screw' fastenings, which are quite common for fixing windows in GRP boats. I don't know the proper name, but in effect a countersunk (or raised countersunk) machine screw is tapped for a smaller through-thread and another csk screw screwed into the thread from the other side (i.e. no nut is needed). There is no reason why the thread couldn't be blind, so that there is no drilling through the slot of one of the screw heads. -Gary
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Post by terrier060 on Jan 10, 2019 17:37:41 GMT
Good thinking Gary - the screw heads look pretty small so a pretty fine thread will have to be used - probably 10 or 12 BA. I notice on Boxhill they have eight on the inside but only three on the outside so the problem does not occur. But Fenchurch has the same eight each side. Ed
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Post by Jim Scott on Jan 10, 2019 20:10:36 GMT
Hi Ed I found this reference to a 'Stroudley Cab Window' in an old publication. Not necessarily from a Terrier but it may be relevant. From other photos there are eight screws fitted from inside the cab, ie round-head with slot. On the outside there is a corresponding dome which may be a tapped insert or might just be the end of the screw with a rounded profile. It doesn't appear to have a screwdriver slot though. I would imagine that the three screws inserted from the outside on 'Boxhill' and spaced between the others, is a later mod when the eight 'screw ends' in this case seem to be finished off flush or the holes filled.
What I have done with mine is tap the outer glass retainer 12BA with clearance holes in the inner retainer, the screws will be finished to length with the ends rounded to suit. Jim
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Post by terrier060 on Jan 10, 2019 20:42:07 GMT
Thanks Jim that's very helpful. I know now what I will do. Great.
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Jan 10, 2019 23:02:33 GMT
Hi Ed,
re the spectacle glass frames, Jim is referring to a F.C. Hambleton drawing in ME. There is a clearance hole through the steel cab sheet for the brass screws holding together the inside and outside spectacle glass frames. Like Jim, I did all mine as per the above and with 12 BA screws, except I fitted each frame with 6 rather than 8 screws. Countersunk screw heads inside the cab (fullsize they had slightly 'domed' heads, but not round heads). Jim and I used the same supplier for the glass.
Cheers,
Julian
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Post by terrier060 on Jan 11, 2019 10:54:57 GMT
Thanks Julian - I had kept some thin glass ready for the windows, but it fell and smashed on the floor a few days ago, after being on the shelf for 20 years or so! Me being careless - it smashed into nasty pointed strips! I suspect one can get Pyrex glass which should be tougher? There is a local firm that will cut it in Bridgend I seem to remember.
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