Automatic Cylinder Cocks

[Tony K]

Does anyone know whether this works? It seems too good to be true to me.

[Deleted]

Knowing my luck the ball would always be up against the plug when I opened the regulator.

Maybe a pin to stop it rolling any further left than in the drawing?

I've got an inside cylinder jobbie with one (near invisible) drain so it might be worth trying for the cost of a bit o' brass.

[baggo]

Hi Tony,

Yes, they work ok. We tend to use similar designs for 2½" locos where the operating gear for normal cocks would be difficult to fit in or a bit flimsy. My Helen is fitted with them. However, I would make the seat as in a clack and seat the ball with the usual 'tap' with a hammer and drift.

John

[JDEng]

I must admit I'm a bit sceptical. The point of cylinder drains is twofold: a) to get rid of condensate when starting away with cold cylinders and thereby prevent damage to the valves/cylinder end covers (at least in a piston valve engine) and b) to allow a means of escape for steam when the loco is standing should the regulator be "passing" slightly and thus preventing a potential runaway.

I would have thought that this style of valve might get gummed up with cylinder oil which would affect its action and, although I've never tried it so admit I may be wrong, I would have thought that the action of anything passing through the valve, whether steam or water, would have a tendency to close the ball against the face; if this happened before all of the water had been exhausted (it sometimes takes several revolutions of the wheels on cold cylinders) it could have disastrous consequences.

As for the snifting valve theory; to be honest snifting valves are really present to allow a trace of cooling air through the superheaters to prevent them burning out when drifting; they're normally fixed to the superheater header or the valve chest. I cannot see what good it would do having the air coming directly in to the cylinders; it will tend to cool them down which is the last thing you want when you've just got them warmed through.

Personally I'd be a bit careful. Does anyone know if there was a full size version?

John.

[fostergp6nhp]

Riddles/Ivatt class 2 full size had a similar device on the valve chests for water drain.

[Shawki Shlemon]

I have used them , they work well , the only thing to remember is you have no control over them and you can't open them after you open the regulator . When stopped , regulator shut , they will drain the water from cylinders .

[JDEng]

Feb 26, 2010 21:02:10 GMT fostergp6nhp said:

Riddles/Ivatt class 2 full size had a similar device on the valve chests for water drain.

Fair comment, as I said I've never heard of them. I take it the Class 2's had normal cylinder drain valves though?

John.

[fostergp6nhp]

Yup the Ivatt had manual poppet valves and the Riddles had BR Std steam operated valves.

[tedholloway]

Auto Cylinder Cocks they are absolutley fine, I've fitted them to a 'Sweet Pea' and a 'Mountaineer' admittedly slide valve engines which system of course allows that bit of lift to get rid of surplus water, but also to a 'Swiss Molly' with piston valves which in my case are an extremly good fit being made of 'Flurosint' ( I think thats how you spell it). However the cylinders on this latter are fitted with PRV's which if there was overpressure would operate. This loco, (see front cover ME Dec 31-Jan 14) Is used as a club hauler and has covered last year about 80 miles with a passenger and truck load of an average around 1 Ton without blowing the covers off.

[pauldenney]

I had a look at making some of these for Tich, but was informed that they only work with parallel cylinders, not inclined, This makes sense when you think about it.

Paul

[russell]

Paul,
They'll work if you mount them side to side instead of parallel to the cylinders!

Russell.

[robmort]

A simpler solution which is also better for scale models, especially small ones, is to install the ball valve in the bottom of the cylinder wall ends, then you don't have to make separate fiddly devices.

This method is shown here:
www.modeng.johnbaguley.info/locos/25inch/A1/A1-2.htm

- bottom of page.

[pault]

Hi All
For me Shawki’s post which says “you can’t open them with the regulator open” says it all. When you open the regulator with cold cylinders you create lots of water. The ideal thing is to vent the water and keep adding steam to warm the cylinders quickly. Personally I can’t see how the turbulence that is supposed to move the ball off the seat is created as there is no significant, if any flow through the valve. Interestingly a free floating ball is used large size gauge glass fittings to seal off the fittings in the event of the glass breaking, allowing the shut off cocks to be used safely. They work on the principle that the flow of water or steam will lift the ball onto the seat, and they do work, I have seen them do just that. As a result I am very sceptical that the laws of physics that allow the balls to seal the gauge glass will also allow the drain cock to open to allow water out. Clearly they will allow water to dribble out when the loco is standing and there is insufficient flow to lift the ball onto the seat.
As for them working as snifting valves yes they will it makes perfect sense. However the main reason for snifting valves to destroy the vacuum created when drifting, not for superheater cooling. They will do the intended job but as stated they will cool the cylinders which is counterproductive.
All that said I have never tried them myself so maybe someone can prove me wrong
Regards
Paul

[robmort]

It is clear that they do work as several have testified, and the principle is easy to test as described in the first post. This means that they can be used exactly like manual versions as when the regulator is open they will still drain water until there is none left, so the cylinders will warm as quickly as possible.

[pault]

Hi Robmort
I have a great respect for Shawki and what he has to say, his comment that they do not work with the regulator open makes sense to me. As for taking a mouth full of water and blowing it through the valve to prove it works, I would suggest it has little relevance. As an absolute maximum the human lungs generate just over a couple of PSI, so the pressures and hence flow rates will be way off anything developed in even a relatively low pressure model. Also if the water opening the valve bit works how do horizontal injector clacks without springs ever work?
Personally I have a need to understand how or why things do what they do, and maybe it is just me being dumb but I can’t see how these work other than when the regulator is shut and the loco static. The only thing that I could possibly see them doing on the run is giving a quick spit at the end of the exhaust stroke
Regards
Paul

[robmort]

Pault,

the fact is many people use them successfully, see for example
modeleng.proboards.com/index.cgi?action=gotopost&board=general&thread=3948&post=50963
where he says that members of his club swear by them.

[Shawki Shlemon]

As I mentioned above I have used them on engines with sliding valves on the side or at the bottom of cylinders , they are OK . The drawing I have from AME is slightly different than the one shown .

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