Dear Stewart

I have been trying to sort this out, steam operated drain cocks for ages, I would be interested with any drawing.

Kind regards

Mick W

Edited By JasonB on 16/01/2020 15:41:42

Looking at the index to Model Engineer at **LINK**

There are two references to 'Steam Operated Draincocks' but that doesn't mean there are not others under references to particular model designs.

Model Engineer 2007 Volume 198 Issue 4292 Page 143
Model Engineer 1985 Volume 155 Issue 3758 Page 165

In 2015 there was a short article on Steam Operated Drain Cocks in David Carpenter's Model Engineers Website. I like the design and eventually plan to make a set as described by Peter Squire.

Usual "for personal use only" applies to downloads, so check the website:-
**LINK**

Doubt there's a problem with me showing the article's heading:-

(You could PM me if interested)

My preference is for manually operated drain cocks.

If the engine starts to prime , you can open a manual drain to release pressure and prevent damage to the cylinder, piston, etc.

Paul.

Maybe someone can help me, I downloaded some time ago this picture from a steam operated drain cock. This is all I have , is there someone recognize this part ? And maybe can help me with the rest?

Kind regards Hans

1. drain in

2. drain out

3. valve head

4. O ring

5. Gland nut

6. ferrule

7. Out of shot – live steam line

Simples – perhaps all that time spent trying to get them to work wasnt a complete waste! Whats not shown is that you will also need a steam relief valve to release pressure to operate the valve.

I made some from the US model engine maker from a long time ago. I made my copies about 10-15 years ago now.

Work great! Piston valve engine, so wanted something that would act as a relief valve if required.

The one Hans shows above would be better than the ones I made; rather than annealing brass disks, the o-ring makes it simpler.

Great little addition to a locomotive.

I cosidered this type of design for my steam lorry – a large piston valve engine. I was cocerned that they would be rather poor at pressure relief because you would get the live steam line full of codensate. In the event of hydraulic lock on the engine, you have to shift a load of condensate in the actuation line – with it's own inertia. So I concluded it would not prevent damage to the engine. If someone has evidence to the contrary, I would be pleased to hear it.

Martin

Consider it my way round. The diameter of port 1 scales at half the outside diameter of the Oring, so the areas are 4:1. The area exposed to cylinder pressure is 3/4 of that exposed to boiler steam pressure, and so if cylinder pressure is 1.333 * boiler pressure the valve will open. The other way round you need cyl pressure = 4* boiler pressure to open it.

As Fizzy says, both work. The drawing implies port 1 is exhaust as there is no thread to secure it.