# Cylinder drain cocks



## pappde (Jan 21, 2014)

I want to elicit the expert advice of our Live Steamers on the topic of drain cocks.<br>On small scale models 1:13 to 1:22 is there a REAL need for cylinder drain cosks?<br>Is it more fore the eye/engineering challenge or is it function?<br>P.S. I understand the function and necessity of cylinder drain cocks on larger scale and full scale locomotives.<br>Thanks: Denes<img smilieid="7" class="inlineimg" src="http://forums.mylargescale.com/images/smilies/rolleyes.gif" border="0"><br>


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## Semper Vaporo (Jan 2, 2008)

If the engine uses "D" valves, they often will lift on excessive pressure and release the water from the cylinder, but it often requires some external power (your hand) to push the engine to get enough pressure to lift the valve off the seat (it is being held down by the pressure of the steam above it and that same pressure is what is moving the piston that is pressing against the water to be removed).

Piston valves can be a problem since they don't lift. In that case, the only way to get the water out is for it to seep between the power piston and cylinder walls or the valve piston and its cylinder walls. Tight seals formed by "perfectly" machined parts and thick oil can produce a hydro-lock that can be near impossible to get rid if. I have heard of people that had to remove a cylinder cover to get the water out! In that case, cylinder cocks are a definite plus!


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## Gary Armitstead (Jan 2, 2008)

pappde said:


> I want to elicit the expert advice of our Live Steamers on the topic of drain cocks.<br>On small scale models 1:13 to 1:22 is there a REAL need for cylinder drain cosks?<br>Is it more fore the eye/engineering challenge or is it function?<br>P.S. I understand the function and necessity of cylinder drain cocks on larger scale and full scale locomotives.<br>Thanks: Denes<img smilieid="7" class="inlineimg" src="http://forums.mylargescale.com/images/smilies/rolleyes.gif" border="0"><br>


In my opinion and with 40 years operating live steam locomotives..........you DO need cylinder cocks. In the smaller scales in the garden (as you mentioned above) with water in the cylinders between the piston and the cylinder heads, you will have hydro-lock. The worst that can happen in this scale is that the loco will not move. In 1/8th scale on up to and including full-size locos (I have experience in 1/8th scale owning/running a Mogul and a Pacific), enough water can build up in the cylinder, to literally blow the heads off the cylinder block.


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## Gary Armitstead (Jan 2, 2008)

Deleted double post.


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## David Leech (Dec 9, 2008)

I only have 1:32 scale models that do NOT have drain cocks, and they don't seem to have any problems.
Any steam that has condensed into water, or water that has entered the steam line when the loco was inverted, just gets blown out the exhaust when you push the loco.
Unless your cylinders are a lot larger, I would think that the same would apply.
Drain cocks are nice, so that you do not coat your pristine loco with water when starting, or splash onlookers, but you can learn to live without.
All the best,
David Leech, Delta, Canada


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## Nick Jr (Jan 2, 2008)

I have seen first had what happens if you try to compress water in a piston valve engine. As David said, a much bigger cylinder. Friend had a Chevy Suburban with the diesel engine that was initially designed as a gasoline engine. The head gasket weeped into the cylinder and when his wife attempted to start it, the connecting rod broke. 
Could easily see how the D valve assembly would be more friendly to condensate in the cylinders as most all of mine are thus. Unfortunately my K4 just leaked steam out of the cocke's for no reason what so ever, they were never used. When I called the manufacturer to inquire a fix, I was told I must have hit switch controls. Rather than argue, I just said Thank You and moved on. I sealed them and have had no trouble ever since. While it was cute to see, I just couldn't see wasting the steam power that was being blown out of it. JMHO


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## pappde (Jan 21, 2014)

Since I finished my first garden loco (Kleine Dicke in 22.5) I am thinking on a new project, of a highly detailed and well equipped small loco, based on the Kleine Dicke.
One of the added features would be cylinder drain cocks, operated by servo.
Hence the question.
My next inquiry would be, what do you think is a good cylinder drain solution for a 1:22.5 scale locomotive would be?
Something thet is not too much out of proportion and also works.
Thanks: Denes


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## weaverc (Jan 2, 2008)

I recommend you get the advice of David Bailey. He can advise you, but he also makes and provides draincocks to fit most locomotive. See his stuff here: http://www.djbengineering.co.uk/ His drain cocks are under the Live Steam Fittings tab.


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## derPeter (Dec 26, 2010)

Hallo together,
in my opinion this matter depends if the loco has 2- 3- or 4cylinders.
2-cylinder-loco can easily pushed forwards to spill out water, 4-cylinder-loco (e.g. T1) will block like a mule.. ;-))
greetings derPeter


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## Chris Scott (Jan 2, 2008)

Denes;
This is a link to an old The Home Machinist forum thread on Linkage Operated Cylinder Drain Cocks http://www.chaski.org/homemachinist/viewtopic.php?f=8&t=73078

DJB MODEL ENGINEERING LTD (David Bailey, UK) offers Automatic Drain Cocks; Look under Live Steam http://www.djb.brushhouse.co.uk/index.shtml


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## HMeinhold (Jan 2, 2008)

In model engineer a couple of years ago someone described extremely simple automatic drain cocks. I think Bill Allen tried them out. He might comment if he reads this thread.


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## Chris Scott (Jan 2, 2008)

Denes,
I have a set (4) of David Bailey's Automatic Drain Cocks - one of those great projects forever in the plan. If you would like them send me an email or PM.

s2sonoma3 @ gmail . com


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## pappde (Jan 21, 2014)

Thank you all.
I have a set of those automatic draincocks. I think they would look much better on a 7/8ths locomotive. On 22.5 they would be too big. And on my loco the cylinder blocks hang relatively low, so they might touch the rails.
I picked up this idea on the German forum:




























The rod should be a tight fit.
Cylinder cover on front end seals distal end of the rod, a tight fit or o ring seals the rear end?


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## Kovacjr (Jan 2, 2008)

bore needs to be drilled and reamed and the rod be precicision ground. Easy stock material. No seals just the tight fit. Ream it for 2.5mm and use a 2.5mm ground rod. Will go in only straight on and be a smooth fit. 

Hard to drill that small hole long distance without wander though.


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## pappde (Jan 21, 2014)

Kovacjr said:


> use a 2.5mm ground rod. Will go in only straight on and be a smooth fit.


Would you use stainless steel?


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## Kovacjr (Jan 2, 2008)

Yes Stainless or tool steel one of the few materials you can get in a ground finish. SS will drill easier than the tool steel. Either will be fun at that small dia.

Not easy to get 2.5mm but you can use the .093" and reamer will be cheap too.

You have a mill to drill this? Not sure Id attempt in a small drill press

http://www.mcmaster.com/#88915k12/=120ru5e


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## pappde (Jan 21, 2014)

Hi Jason,
How about this:

http://www.ondrivesus.com/documents/pages/shafts-303SS-GS-GSM.pdf

and if it is too hard to drill holes, just cut two 1mm slots a little over half the cross section of the shaft?


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## bille1906 (May 2, 2009)

In my opinion, automatic drains are the only way to go. the cylinders are outside the track so they really cant hit the track. I don't think they stick down any more than the manual ones. I have them on two 1/32 engines and they work fine with plenty of clearance.
There is a diagram of them on my "Making Parts" thread


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