Loco cylinder drain cocks

[Garry ColesParticipant @garrycoles69390]

Hi,

I posted the question the other day about which type of drain cock modellers prefer use, auto, lever or steam operated.

I would like to use the steam operated ones, but can’t quite see how they work from the drawings I have. I take it that when you open the steam valve, it opens the cock to drain. But what I see it doing is pushing the small valve towards the drain hole and blocks it. Or am I missing a simple operation here that confuses me. Can someone please explain the workings for me.

Thanks

Garry

[JasonBModerator @jasonb]

Not  a loco man but I think you run them with a two-way valve. When steam is connected as you say it closes the cock as pressure will be on both sides. Turn the valve the other way so it is open to air and the pressure in the cylinder will push the plunger open and drain the cylinder.

[Garry ColesParticipant @garrycoles69390]

Thanks Jason, but that means steam pressure has to be applied all the time. But I thought you open the steam vavle when you want to drain the cylinders of water.

[Brian Baker 2Participant @brianbaker2]

Greetings Garry, for a non loco man Jason has a good grip on steam operated drain cock operation.  When steam is on, they are closed, but will still open to relieve a hydraulic lock.  Shut off the steam and the steam in the pipe condenses allowing the pressure to fall and the drain cock will open, or as Jason described you could use a 2 way valve allowing the steam to vent.

I prefer to use a single on off steam valve to apply them and a “condensate drain valve” to automatically vent them.  A ball, held closed by steam pressure against a seat by a weak spring, will lift as steam condenses and pressure reduces, automatically.

I think it is easier to make than the usual rotating disc two way valve which always seem to leak.

Regards

Brian B

[DurhambuilderParticipant @durhambuilder]

Try these, drawings and description, not sure I understand how they work but they do.  http://ibls.org/mediawiki/index.php?title=Automatic_Cylinder_Cocks

[Derek DroverParticipant @derekdrover32802]

I use steam drain cocks on both my 5″ gauge locos, they’re very simple to plumb-up (easier than fiddling around with links)…

The valve I have made has two positions:-

On – steam is applied from the boiler to the drain cock and closing them (but will be forced open in the event of hydraulic lock).

Off – the pipes leading to the drain cocks are vented to atmosphere so releasing the pressure keeping them closed, enabling them to open with very little pressure on the drain side of the cylinders.

They can be susceptible to failing to close if any muck gets into them, but they’re not difficult t unscrew and clean.

If you pm me your email address I’ll take a photo of my valve (there’s no drawing), I just make them to suit.

 

[Durhambuilder]

On Durhambuilder Said:

Try these, drawings and description, not sure I understand how they work but they do.  http://ibls.org/mediawiki/index.php?title=Automatic_Cylinder_Cocks

I made a set of those for a steam pump.  I found that cylinder oil makes everything sticky and keeps the ball on the seat regardless.  Consequently they don’t vent condensate.

Martin

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