Author Topic: Cylinder Drain Coxs  (Read 28316 times)

Offline Dan Rowe

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Re: Cylinder Drain Coxs
« Reply #30 on: July 27, 2012, 01:53:02 PM »
Pete,
Yes the Chaskis website is a gold mine of large scale locomotive information. One of my favorite posters over there is Bill Shields. He is a steam engineer who builds 3/4" scale locos.

Here is the link to where he has a few useful drawings including of course another steam operated drain cock in the misc section.
http://www.mehrs.com/

Dan
ShaylocoDan

Offline sbwhart

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Re: Cylinder Drain Coxs
« Reply #31 on: July 27, 2012, 02:00:28 PM »
Dan

Thats a real usful site with some very interesting drawings

Thanks for sharing

Stew
A little bit of clearance never got in the way

Offline doubletop

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Re: Cylinder Drain Coxs
« Reply #32 on: September 06, 2012, 10:26:11 AM »
You may recall Stew made 6 auto drain cocks and offered the two spares to a good home. Well they arrived in NZ today and it didn't take long to get them fitted.



Thanks a lot Stew the are great. Hopefully the weather will hold out for the weekend and I'll be able to try them on my first steaming and give you a report.

Pete
« Last Edit: July 16, 2017, 09:21:12 AM by doubletop »
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline doubletop

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Re: Cylinder Drain Coxs
« Reply #33 on: November 08, 2012, 09:51:33 AM »
I tried Stews automatic cocks but couldn't get them to be closed when I thought they should be closed or open when I thought they should be open. To be fair I didn't give them a fair chance as I had other things that needed attention. Time moved on a bit the weather was bad so I couldn't run so I thought I'd use the time make some steam operated drain cocks.



(flex hose is the compressor line fitted to the lubricator clack. I find that the easiest option when testing on air as with the regulator closed the boiler doesn't get pressurized)

They are based on the drawings on the link posted by Dan http://www.mehrs.com/cylinder_cocks.zip I liked the look of these but they didn't work for me either. They'd be open at the start but once closed they wouldn't open again. Even with the steam 'off' pushing the shuttles back with a 1/16" rod I could feel pressure behind them keeping them closed.  I tried all sorts in an attempt to work out why they wouldn't open again. Then it occurred to me tonight the the setup that came with the loco, of a simple steam valve in the cab, wouldn't work. Once pipework was pressurized there was no way to dump the pressure. That then explained why Terence Hollands valve in ME4433 was more complicated than I had thought necessary, his is the only drawing of an operating valve I've seen. It allows the pressure in the pipe to be vented. So that's the job for the weekend, make one.

I've also fitted Stew's two valves with two steam operated valves to do a comparison. I'll report back

Pete
« Last Edit: July 16, 2017, 09:21:46 AM by doubletop »
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Stuart

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Re: Cylinder Drain Coxs
« Reply #34 on: November 08, 2012, 11:14:28 AM »
Pete

 the valves that Stew sent you do work I have some on a class 2 and they are fine


as to your steam operated ones

1 the stam lines are far to big I used 1/16 od pipe on the class 4 tank
2 you need a valve that when you shut off the steam it opens a port to atmosphere , not a screwdown one but a rotary one with two ports one to your steam supply and one to air with the outlet to the valves,

on the class 4 they are one the same line as the atomiser for the steam oil so when the steam is on the atomiser runs and the valves close and visa versa with the atomiser doing the pressure release

I uses a ptfe slug for the valve in the cock and used a center drill up the back end to form a skirt to make a lip seal

Stuart
My aim is for a accurate part with a good finish

Offline doubletop

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Re: Cylinder Drain Coxs
« Reply #35 on: November 09, 2012, 10:29:48 AM »
Stuart

Thanks for the post. I saw it this morning and have spent the day waiting to get home.

I'm not suggesting there is anything wrong with Stews auto cocks. circumstances meant I didn't have the chance to try them properly. The plan is to try them again this weekend. They are already fitted to the loco along with two steam operated cocks.

The steam lines are 5/32" or 4mm which is what I had available and was similar to the steam feed from the backhead. I had no other point of reference to determine whether that was correct or not, I had assumed what had been fitted originally was "right". The loco came with the steam feed pipe capped off, a screwdown valve and four individual manual drain cocks. I had assumed tat the steam drain cocks had got themselves ripped off at some point and what was fitted was a quick fix. I now believe the steam operated drain cocks never worked properly so were replaced.

Your point 2 is what had me thinking as soon as I read it, something based on a rotary reverser sometimes fitted to "wobbler' engines. I got home tonight, sketched it up and have most of it made. just the steam connections to be turned and silver soldered in the morning and we'll see if it works. Lets call it a prototype for now. The drain cocks themselves are to the drawings I linked to.

So thanks for the input it triggered some thoughts on an alternative option and hopefully it will do the job, we'll see how it goes .

Pete
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Stuart

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Re: Cylinder Drain Coxs
« Reply #36 on: November 09, 2012, 11:39:27 AM »
Pete

glad my post provoked some thought


often the seed  to sort out the problem produces a better end result that has been done before

check your PM I cannot post because of Copy write issues

Stuart
« Last Edit: November 09, 2012, 11:49:46 AM by Lordedmond »
My aim is for a accurate part with a good finish

Offline doubletop

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Re: Cylinder Drain Coxs
« Reply #37 on: November 11, 2012, 07:36:14 AM »
With the input provided by Stuart's comments I set about making a  rotary valve for the steam drain cocks and had it installed ready for a try out by Saturday lunchtime.



I also installed Stew's auto drain cocks to try them side by side.



I can report that Stew's auto drain cocks work fine. They allowed the water in the cylinders to drain, ejected any excess on starting the loco and then shut off when running.

The rotary valve also worked fine controlling the opening and closing of the steam operated drain cocks as expected. The only problem I had was when the valve was in the position to open the drain cocks the two faces leaked steam slightly because the port from the boiler manifold, at boiler pressure, was closed off by the valve face forcing the faces apart.  When in the position to close the drain cocks the boiler pressure was acting down the length of the feed pipe to the drain cocks and the leak didn't occur for some reason. In all it wasn't bad but not perfect.

Sunday started as wet and windy so needing something to do I made a version of the valve Terence Holland had featured in ME



I'll get it fitted and give it a try at some point.

Pete
« Last Edit: July 16, 2017, 09:19:16 AM by doubletop »
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline sbwhart

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Re: Cylinder Drain Coxs
« Reply #38 on: November 11, 2012, 07:40:38 AM »
Good to know you're making progress Pete thanks for keeping us posted.

Stew
A little bit of clearance never got in the way

Offline Stuart

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Re: Cylinder Drain Coxs
« Reply #39 on: November 11, 2012, 08:03:36 AM »
Pete

glad my info sparked a fix


Stuart
My aim is for a accurate part with a good finish

Offline doubletop

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Re: Cylinder Drain Coxs
« Reply #40 on: November 17, 2012, 05:51:24 AM »
Stuart sent me some diagrams of similar rotary valves. those had O rings in the steam feed port. So trip to the local O ring vendor this morning and I had some 1/16" x 1/16" cross section O rings. A retrofit to the existing valve wasn't going to work the way I'd done the end stop on the Mk1, so a case of start again.

The Mk1 and Mk 2 versions



Installed



Yet to try it out its raining at the moment.

Pete
« Last Edit: July 16, 2017, 09:17:46 AM by doubletop »
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline steamer

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Re: Cylinder Drain Coxs
« Reply #41 on: November 17, 2012, 11:34:46 AM »
Nice set up Pete!   Viton rings?

Dave
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Damned ijjit!

Offline doubletop

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Re: Cylinder Drain Coxs
« Reply #42 on: December 29, 2012, 12:21:09 AM »
A bit of an update on this. I couldn't get the rotary valve to seat sufficiently in the end I went for the plunger type valve from ME article.



And mounted it vertically in the cab floor as its too long to go on the manifold where I had the rotary valve.



I also modified the drain cocks so they vent forward and not down or sideways. Down picks up a lot of rubbish from the track bed especially at ground level and sideways is a bit inconvenient for bystanders, especially on a raised track



In hindsight that decision proved itself to be a good one when starting off for the very first time the jet of water can shoot 10 feet ahead of the loco.

The decision to go with the steam operated drain cocks has also resolved a problem that I'm beginning to think was the cause of the state the loco was in when I took it over. The crossheads, bushes and pins were all seriously worn out. When I first ran the loco with the manual and automatic drain cocks it knocked to some extent. I'm guessing that as the original steam drain cocks had never worked the previous owner had replaced them with four individual manual drain cocks. They would have bee impossible to operate on the move so could only be opened when stopped and closed prior to driving off. That would never have got rid  of all the condensate water and hence the loco would have knocked. I'm guessing that auto cocks would have this problem to some degree as once the regulator is opened and pressure is applied they will close regardless of whether there is water still in the cylinders. Remotely (steam) operated drain cocks give the driver full control and they can be held open when pulling away ensuring all the water is ejected the cylinders come back up to temperature

This short bit of video with me opening the drain cocks (and blow the whistle) for the camera as I go by.

<a href="https://www.youtube.com/watch?v=aq8ePsbRBR4" target="_blank">http://www.youtube.com/watch?v=aq8ePsbRBR4</a>


Pete
« Last Edit: July 16, 2017, 09:09:27 AM by doubletop »
?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline sbwhart

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Re: Cylinder Drain Coxs
« Reply #43 on: December 29, 2012, 08:27:27 AM »
Great Job  :ThumbsUp:

Stew
A little bit of clearance never got in the way

Offline Allysnell

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Re: Cylinder Drain Coxs
« Reply #44 on: June 28, 2019, 10:40:11 PM »
Hi guys I am look g for plans for the plunger type valve pictures in this thread, I think I know how to construct it however if anyone has better pictures or even better, plans, then that would be awesome. Ally

 

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