[modeleng] Re: Valve Problem
- From: "Barrie Purslow" <bpduo@xxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Sat, 30 May 2009 21:57:30 +0100
----- Original Message -----
From: "R.L. Roebuck" <rlr20@xxxxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Saturday, May 30, 2009 8:59 PM
Subject: [modeleng] Re: Valve Problem
> Hi there Bede,
>
> I might be wrong, but fundamentally I think there is going to need to be
> some stripping down.
>
> BUT there are four areas it could be that need stripping down - two
> cylinders and two valve chests - so anything you could do to narrow the
> problem down would be a good plan.
>
> I'd avoid trying any further running until you have sorted the problem, as
> if it is a lump of some clinker preventing the valve from seating onto the
> port face then the more it moves, the more it could be scoring a line in
> the port face.
>
> Also I'd be tempted to make sure you fully sort the problem when you find
> the cause (ie if it is clinker in the valve chest, then it will get in
> there again if you don't make some kind of modification, do you have a
> snifting valve for example, and does it work).
>
> Now for checking things out:-
>
> Do you have drain cocks fitted to the loco - if so this will make life
> much easier?
>
> If so, how about on each cylinder, unscrew the drain cocks (careful not to
> shear them off). Set the loco in full forward gear, close the regulator.
> Make yourself a fitting so you can pump water into where one of the drain
> cock fittings was. Turn the loco wheels till the port corresponding to the
> end of the cylinder where you have this fitting attached would be being
> supplied with live steam. Now try pumping water into this end of the
> cylinder. If I'm right - if that cylinder and valve are in good nick you
> the pump should quickly become rigid indicating no leakage (well you might
> get a bit) - don't pump too hard though. If water comes out of the other
> drain cock hole on that cylinder or the blast-pipe, then the cylinder or
> valve on that side is at fault. Try both sides of the loco to work out
> which side the fault is on.
>
> Next to work out whether it is the cylinder of the valve. On the fault
> side, have your device for feeding water into one drain cock fitting
> fitted, and plug the other drain cock fitting. If you now try pumping
> again...if it goes rigid then the fault is the cylinder. If water starts
> coming out of the blast pipe, then the valve it at fault (noting that one
> could expext slight weeps as not a major problem).
>
> What do you reckon everyone - will that likely work?
>
> Yours,
>
>
> Rich.
>
>
> On Sat, 30 May 2009, bede@xxxxxxx wrote:
>
>> Thanks all for your responses on this.
>>
>> I put the engine up on blocks and got the boiler up to working pressure
>> on air. When I open the reg, the air whooshes out the blast pipe, BUT,
>> the wheels do spin feebly about 10 or 15 revs before the pressure dies.
>>
>> So maybe the valves are seating and it's something else? Or one valve
>> is unseated and the other is doing the work? or could this be piston
>> ring issues? That would be more incremental it seems, and this problem
>> occurred all at once.
>>
>> Any further thoughts as to what to look for as I begin to strip the loco
>> down?
>>
>> Thanks as always,
>>
>> Bede
>>
>>
>>
>> On 5/26/2009, "bede@xxxxxxx" <bede@xxxxxxx> wrote:
>>
>>> Hi All,
>>>
>>> Looking for help troubleshooting my Martin Evans' "Conway", 3.5"
>>> gauge narrow gauge 0-4-0.
>>>
>>> Tried to steam the loco over the weekend and it raised steam ok to
>>> working pressure (80psi), but when I opened the regulator/throttle, the
>>> steam just whooshed directly up the blast pipe, no power to the
>>> cylinders at all in either direction, tried pushing the loco back and
>>> forth, but no luck.
>>>
>>> I have to admit that I did an idiot thing- the smokebox was full of
>>> cinders and ash and my steaming buddy and I took the lazy way out and
>>> tipped the whole engine upright to dump the debris out. I'm thinking
>>> now that this somehow caused one or both valves to become unseated which
>>> resulted in the steam just going straight out the exhaust port. This
>>> loco has outside cylinders with the steam chests inside the frames,
>>> Stephenson gear with the slide/D valves vertical against the port faces.
>>> But I can't imagine the valves coming away that easily, esp. as
>>> they're vertical...
>>>
>>> Any suggestions on what steps to take to remedy this, I really hope I
>>> don't have to strip the loco down...
>>>
>>> Thanks,
>>> Bede in breezy Brooklyn
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