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Post by Roger on Sept 30, 2014 11:20:18 GMT
Now that's a really simple idea, I like that. It would be very easy to make a reduction gear that would fit inside the lubricator. Once it's set, you wouldn't need a bypass valve to control it, but I still favour a sight glass. It's all very well adjusting the output of the pump but I can see what you mean about the minimum rotation per tooth. I guess trying to make that finer could result in it not working reliably. Also, very small deliveries per stroke might be an issue. It might need a two piston pump to guarantee a more even flow though. Food for thought!
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pault
Elder Statesman
Posts: 1,496
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Post by pault on Sept 30, 2014 12:14:40 GMT
Hi All I don’t think having a safety valve style valve would be of any benefit as you will still get pressure fluctuations. When coasting the pump would have to work against the spring pressure, be it whatever. When working hard the pump would have to work against the spring pressure plus the pressure of the steam pushing against the valve. In effect the pressure fluctuations would be the same as if there was no valve just at a higher pressure. As far as a mechanical lubricator goes there is little need for sight glasses, you soon get to know how much the oil will fall in the tank each trip, so you get a check on how its working each time you look in the tank. As far as delivery goes you have two options for governing the amount of oil delivered. One is the drive which if it is a ratchet is limited to a minimum of one tooth per rev. You can always make a wheel with more teeth if this is too much, or use a clutch which will work down to very small movements. The other way is to control the volume pumped with each stroke as in the Jim Ewins design. Once set up properly they require no further adjustment as they adjust for speed themselves. Whilst I would not argue that a properly designed and made Hydrostatic system will work well it is one more thing to remember and fiddle with which if you are learning the ropes of driving may well get forgotten or become a distraction to the point of neglecting something else. Overall a properly designed and sorted out mechanical pump gets my vote over a hydrostatic one after all the GWR only had them to be different to everyone else, not because they were better (puts on tin hat)
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Post by Roger on Sept 30, 2014 12:29:30 GMT
Thanks for that Paul, I think you're right about the relief valve, that's not the answer to getting a constant pressure. I think it's fair so say that mechanical lubricators in general tend to be set up to give far more than hydrostatic ones and there does seem to me to be a case for controlling that better. I wonder how reliable they become if you reduce the stroke to give the sort of output a hydrostatic lubricator gives? I'm definitely going to provide a sight glass, I like the look of them and it's positive way to see exactly what's going on. I really like the idea of gearing down a pump rather than reducing its volume too far. Mechanical lubricators obviously work really well and I guess most people just want a guarantee that oil is getting through. If there's no way to see that on a minute by minute basis, I can see why they take a very conservative view of how little oil to use. I like the idea of something that can be adjusted, but I don't see the need to adjust it on the run once it's right.
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pault
Elder Statesman
Posts: 1,496
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Post by pault on Sept 30, 2014 13:52:02 GMT
The main issue i could see with gearing down the drive would be that obviously the duration of each pumping cycle would be much longer. This would mean that the effect of a leak in the pump would be greater than on an ungeared pump. Sealing the ram with an oring would help on this. I have done this on a number of pumps to overcome leaking glands on commercial lubricators.
We have successfully got most of our mechanical lubricators to the point where the chimney is dry and there are no spots of oil on the boiler
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Post by Roger on Sept 30, 2014 14:17:23 GMT
I was thinking the same thing about sealing, I know that some designs don't use seals at all. My instinct is to always fit a seal where sealing is required, they cost next to nothing and it can only help. I might be concerned about long periods with no delivery and that's why I thought of using two pumps. They are so simple that it's no hardship to double them up. I don't see the point in having excessive oil being used, it's only going to make a mess.
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Post by andyhigham on Sept 30, 2014 15:12:26 GMT
Has anyone tried to use a gear pump?
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cotswold
Part of the e-furniture
Still testing the water
Posts: 307
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Post by cotswold on Sept 30, 2014 16:54:02 GMT
I think Jim Ewins suggested one. But that was very many moons ago and my pile of EiM have all been stowed away in boxes.
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Post by digger on Sept 30, 2014 16:54:24 GMT
Sight feed hydrostatic lubricator every time for me, you can see the oil being delivered, you can adjust that rate on the run, when the run is over and everything cooled down, if you drain the water from the oil tank and measure it, then that is the volume of oil consumed during that run. I have fitted a small cycle computer to my tender and at the end of the run, the total distance covered can be read, and calculated against the oil used, it is supprising how small a quantity you need for adequate lubrication, most locomotives are grossly over lubricated, with the attendant mess of oil spots everywhere.
Digger
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Post by Deleted on Sept 30, 2014 20:19:13 GMT
Sight feed hydrostatic lubricator every time for me, you can see the oil being delivered, you can adjust that rate on the run, when the run is over and everything cooled down, if you drain the water from the oil tank and measure it, then that is the volume of oil consumed during that run. I have fitted a small cycle computer to my tender and at the end of the run, the total distance covered can be read, and calculated against the oil used, it is supprising how small a quantity you need for adequate lubrication, most locomotives are grossly over lubricated, with the attendant mess of oil spots everywhere. Digger ------------------------------------the old "Dalmatian Driver"syndrome !!
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Post by andyhigham on Oct 1, 2014 21:15:12 GMT
I have used a hydrostatic lubricator for years, no problems at all. I used about a metre of copper tube from the steam valve to the oil tank, coiled up flat against the cab roof to act as a condenser. I have even used plain water in the sight glass without problems
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 2, 2014 0:39:44 GMT
hi john (JDEng), the reason the GWR locos such as the castles had mechanical lubricators fitted was only on the castles with the improved superheater arrangement in the 1950s. we dont have to worry about such details in miniature due to our lower steam pressures (and hence temperatures even if radiant superheaters are fitted) which cope perfectly well with ordinary steam oil. there is a school of thought that many drivers preferred the old hydrostatic lubricators anyway, adjusting the feed rate for trips such as the Bristolian and Cheltenham Flyer etc. i have it on good authority that the old senior link GWR drivers didnt like mechanical lubricators on their locos! cheers, julian
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Post by Deleted on Oct 2, 2014 1:00:24 GMT
Just out of idle interest, I wonder what the total volumetric capacity was of the oil delivery line from the cab to the point of delivery on say a Castle or Manor ??...............and how would Swindon have initially filled that pipe with oil before the lubricator was started ??
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Post by Deleted on Oct 2, 2014 1:02:37 GMT
hi john (JDEng), the reason the GWR locos such as the castles had mechanical lubricators fitted was only on the castles with the improved superheater arrangement in the 1950s. we dont have to worry about such details in miniature due to our lower steam pressures (and hence temperatures even if radiant superheaters are fitted) which cope perfectly well with ordinary steam oil. there is a school of thought that many drivers preferred the old hydrostatic lubricators anyway, adjusting the feed rate for trips such as the Bristolian and Cheltenham Flyer etc. i have it on good authority that the old senior link GWR drivers didnt like mechanical lubricators on their locos! cheers, julian ------------------------------- I believe those ones had a different grade of oil specified in order to cope with the higher temps as well ??
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Post by Deleted on Oct 2, 2014 1:12:56 GMT
Here's a bit of thinking "Outside the box" -----One form of variable output pump is the swashplate type....Take the rotary drive from any axle, incorporate a centrifugal mechanism to adjust the setting ( Thus output) and you have an entirely self regulating pump !! >>>>>>>>>>>>>>>>>>>>>>>>>>>>
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Post by Deleted on Oct 2, 2014 1:16:09 GMT
OR------ couple the output control lever to the reverser or die block setting to give output proportional to loading.....
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 2, 2014 1:20:20 GMT
hi alan, as you will know from the 'stores' at bridgnorth, mainline superheated locos of the 4-row type definitely had a different grade of steam oil. to prime the system on a hydrostatic lubricator system i think you simply have to start up the system before leaving shed. ive got the original GWR drawings and operating instructions for same for 1932 for the various types of hydrostatic lubricators, but am sure the above comment re priming the system is accurate. cheers, julian
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Post by peterseager on Oct 2, 2014 7:17:27 GMT
and how would Swindon have initially filled that pipe with oil before the lubricator was started ?? On a true hydrostatic system the oil is blown down the pipe by steam from the jockey valve. Peter
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Post by Deleted on Oct 2, 2014 9:21:48 GMT
and how would Swindon have initially filled that pipe with oil before the lubricator was started ?? 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 ??
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Post by Deleted on Oct 2, 2014 9:47:35 GMT
Because the Western had a ridiculous habit of doubling up on useless things, spare condenser just in case, a second whistle for emergencies (western men couldn't remember the whistle code for an emergency so just had a special whistle for the task) and then when a spare was a very useful requirement, say, gauge glasses, only had one and the second method was a stupid tap arrangement which gave you limited readings compared to a nice 2nd gauge glass!
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Post by Deleted on Oct 2, 2014 11:42:01 GMT
Ooopss----I feel a "Handbags-at-Dawn" scenario fast approaching !!----------chuckle !-----------As it happens I too would like to see a 5" gauge version offered on the market....As per Julian I think an 0-6-0 tender design is often overlooked........BEN, you forgot about the WR's double-engined diesel locos and Railcars ( ok, I suppose we'll have to let those ER chaps in with the Deltics as well)...........At this rate I'll be expecting the Spanish Inquisition to call here at any moment !! ( Cue for someone else to put up the relevant You-Tube videos...)...
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