A bit of a puzzle.

[Michael CallaghanParticipant @michaelcallaghan68621]

Hi, I am thinking of fitting a ball valve to replace the not very good popper regulator in my Martin evans designed Columbia. The biggest problem I have is how to fit control linkage to the valve. In the design the linkage from the regulator comes out the side and through the side of the smokebox.
my problem is that the valves control lug is small only 4mm tall. I have been thinking of cutting the original valve handle that fits the valve lug and soldering an arm to it that will lead outside the smokebox. However I need to be able to make sure that the control arm will not lift off the valve lug for any reason. I need to fit the valve first inside the smokebox and then the arm to the valve. Can anyone think of a good way to make sure that the arm will not slip off and yet in case of need be able to be removed . 

[Perko7Participant @perko7]

Two questions:

1. Is the screw in the photo part of the valve assembly holding the mechanism together? Could it be used to also hold the valve handle on?

2. Is the back of the valve smooth and could an extension piece be arranged to bear against the back of the valve to hold the valve handle on?

[DiogenesParticipant @diogenes]

On all the ball-valves I’ve seen like that, it is that screw that holds the handle on. Might be better replaced with a hex-head set screw.

How hot does it get in the smokebox ?

 

[JasonBModerator @jasonb]

I would be worried about heat in the smokebox, these valves tend to have plastic seals on the spindle and the ball also turns in plastic cups.

If it will take the heat as said the screw holds the original handle on so use that if you can with a stainless screw.

[Michael CallaghanParticipant @michaelcallaghan68621]

Hi chaps. The screw is just to hold the handle on. However I need to fit a control arm around 50mm from the valve to the outside of the smokebox. The control arm will need to be central to the control lug on the valve so the screw can not be used. The easiest solution would be to screw the control arm into the control lug using the screw thread. My worry is how to lock that arm in place. Thread lockers I don’t believe will take the heat.

[JasonBModerator @jasonb]

50mm is not so long that you could not drill right through and use a stud rather than a screw, come at it from both ends if needed

If thread lock can’t take the heat then what about the seals in the valve.

[noel shelleyParticipant @noelshelley55608]

I would be VERY wary of using that type of valve UNLESS you have data that says it can take the temp in the smoke box of may be 300c which I doubt it will. If coal fired there is also the issue of erosion and high wear due to char. Noel.

[WearyParticipant @weary]

Owse about …

Rod of suitable diameter (& length!) silver-soldered to a square socket.  Square socket fits over your ‘lever seating’ in order to provide rotational drive.  Then pin with 1.5mm or 1/16″ (stainless) pin through square sections.

Pin only needed to prevent lateral movement so can actually be slim as you like.  Could use taper-pin if you prefer.

 

An alternative approach:

You are going to need a (sealed) tube to allow the operating rod to pass through the smokebox.  If you don’t like a pin through the valve driving square then a collar (with grub-screw? or maybe pin??) positioned to run against the through-tube will hold the square against the driving square on your valve.

Phil

[Michael CallaghanParticipant @michaelcallaghan68621]

Thanks Phil, I think you have sorted it.

[duncan webster 1Participant @duncanwebster1]

The seals are usually ptfe, and the valve itself is fastened to the boiler shell, so it won’t get screaming hot. Loads of Winson locos have this set up, and it is one of the few things that seem to just work.

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