[modeleng] Re: Injectors

Sound like you might be on the right track there Pete - try a washer, fibre,
or for preference, copper, and see wot 'appens


> I know, an old chestnut!
>
> I am babysitting a locomotive for a person who is emigrating, it is a
> 7.25" 0-4-0 "Hercules".
>
> I was at Swindon track yesterday with the locomotive for a boiler test,
> all was well until we came to the steam test. This locomotive has one
> injector and an axle driven pump, so both must work to pass the test.
>
> We tried the injector and it refused to pick.  We changed it for a
> spare, which also refused to pick!
>
> Tonight I steamed it up at home using two injectors from my Hunslet
> (both known to work) and neither refused to pick!
>
> I therefore suspect that it is not the injector itself!
>
> The operation was the same in all cases, water on, steam on, the symptom
> in all cases is excessive overflow.  There is a slight "twitter" as the
> steam is first applied, but that soon goes and the overflow continues.
> Adjustment of steam and water has no effect.
>
> I have looked at the arrangements.  Steam supply is good.  Water supply
> is good, it is from balanced side tanks, 1/4" pipe and gentle curves.  I
> removed the water feed from the injector and it is running free.  All
> joints are tight and "air tight" as far as I can tell.
>
> This only leaves the clack.  It certainly seals as there is no steam
> coming back to the injector from the clack (I swapped enough injectors
> with the loco in steam!)  I removed the top from the clack and all
> appeared well.  The only thing I could see was that the clack used to
> have a fibre washer sealing the top to the body. Only the remnants of
> the washer were left and the clack was sealed using PTFE tape. I don't
> consider the PTFE tape was causing a problem, but could the absence of
> the fibre washer reduce the lift of the ball to the extent that even if
> the injector wanted to pick, it couldn't get rid of the water fast
> enough, causing the overflow?
>
> I am not an expert on injectors, so can somebody advise where to look?
>
> Cheers
>
> Peter
>
>
>
>
>
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