Clack valves

[earlswood nob]

Good morning all
Please excuse me if these are silly questions.
First; were clack valves fitted to both sides of a boiler? I haven't found a photo that shows both sides of the loco.
Second; when were boilers with clack valves replaced? Was it when a boiler with an A suffix was fitted?

Earlswood nob

[jwealleans]

On any particular loco?

[drmditch]

Just checked my sources for J21s and G5s which are open on my desk.
As far as I can see the Darlington boilers from the NER designs had clack valves on both sides.
Was there a particular design you were interested in?

[greenglade]

I would think that this will vary according to class... you need a clack valve for amongst other things putting water into the boiler so one for each injector and then you have the loco's that may also have a form of mechanical pump to get water in.

Pete

[earlswood nob]

G'day all
The loco I had in mind is a J25, for which I have an unbuilt kit. The J25 boilers run parallel with J21 boilers. As I have reopened the wound on my finger again this morning opening a bottle of milk, it's research only for a few days.
Some pics have clack valves and some do not.
It makes sense to have one for each injector, which clears up my first query.
It seems those that have been reboilered with Diag 67A boilers, do not have clack valves. The dome is also moved back.
I have to rush, as I'm off to the smoke with the G/F later.
I am also trying to strike a deal so I can attend the Warley exhib on Sat. It would mean a twenty plus hour day, but I can have a lazy day on sunday to recover.
Thanks
Earlswood nob

[ArthurK]

If an NER loco had clack valves they were both sides. NER locos had two injectors usually fitted below the footplate. Often these were on the ashpan sides (e.g. J 0-6-0Ts) and sometimes behind the cab steps (tender locos). These fed water to the boiler via the clack valves the fitting on the backhead was in fact the steam supply to the injectors.

Later boilers still had the injectors (usually) below the footplate but the clacks were dispensed with. In their place water was supplied to the boiler via the boiler backplate. These now had a combined steam delivery to the injectors and water delivery from the injectors. The single pipe on the backplate was replaced by two, steam out/water in, combined as a single fitting.

ArthurK

[neilgow]

In simple terms, a clack valve is nothing more than a non-return valve. Once the steam/water feed into the boiler via a clack valve ceases, then the boiler pressure will forcefully shut the clack preventing boiler steam escaping. I find it hard to believe that there are locomotive injectors that do not have clack valves in their systems and all clacks will be as close to the boiler shell as possible.

Rgds

NG

[jamieP]

All steam engine have some kind of clack fitted. Either on the boiler backplate or top of the boiler. Most Gresley built engines had them on the boiler backplate and is combined with the steam valve to the injector.

As NG has said they are just a simple Non- return valve.

[ten ten]

If you are able to visit the NRM in the future,there's a very nice model( 5"gauge?) of a NER P1(J25) in the store area just off the main display,opposite Green Arrow.Spent some time looking at it a week ago,making a few mental notes/sketches of details when I start my kit ,particularly confirming the tender handbrake was on the drivers side,and injectors were behind the cab steps.Its as near as we will get to full size reference,apart from its cousin the J21 .Forgot my camera-so another visit is called for next year.

[drmditch]

The boiler and fittings (such as lubricators) will depend on which locomotive and what period you intend to model.
RCTS and Yeadon are probably the best references.
PM me if you would like a particular engine checked.

I need to get back to my second J21 - which will have a Dia 67 boiler - with side clacks, ball lubricator, slide valves - and Joy valve gear!

[earlswood nob]

Good morning all
I've found GER clack valves in Alan Gibson's list. They look pretty close to the NER variety, which interest me.
Earlswood nob

[drmditch]

I think Dave Alexander does a nice brass NER example.

[earlswood nob]

Good morning all
Dave Alexander does some good NER gear, but as he doesn't have a website anymore, it's difficult to know what he does do.
I shall have to get his Q6 soon, so perhaps I get a list with that.
Earlswood nob

[bricam5]

I have never been able to fathom why so many CME's chose to put the boiler feeds on the side or the boiler top. In areas with hard water or impure supply, a sticking clack valve was a regular hazzard and I have had many. With the valve on the boiler face, it was an easy job to screw the clack valve down. Sometimes unscrewing again would free the valve. If not, use the drivers side injector. The firemans side would still work if you unscrewed the clack but then you would have to screw the bloody thing down again.

How many times have you seen shots of Midland locos with steam belching out from under the footplate? Sticky clack? Damned if I would cimb onto the boiler top at 70 mph with a spanner!

[greenglade]

I can't speak for full size but for live steam models a quick temporary fix to a sticking clack is usually a sharp tap across the top of it with the back of the shovel.. of course I'm referring to models with the clacks fitted to the backplate such as Gresley Pacific's which is my experience...I can't say that I've seen live steam loco's with clacks fitted elsewhere but then if they were on the prototype I'm sure some model engineers building a true scale model must have built their models likewise...

Pete