Double Tangye valve attachment

[Tony MartyrParticipant @tonymartyr14488]

The single drawing of the double Tangye engine I have doesn't show the method of attachment of the slide valve to its rod. The valve has a 1/8" hole through which the 6BA portion of the rod must run but I can't see how there is any vertical freedom of movement allowed so that the steam pressure seats the valve on its face while retaining fixed axial position on the rod. My previous engines have had groves in their top faces that housed cruciform ends to the rod – I must be missing something obvious!

[Tony MartyrParticipant @tonymartyr14488]

[JasonBModerator @jasonb]

Use a pair of brass lock nuts either side of the valve with a very small amount of endplay, just enough so the 6BA thread can move about in the 1/8" hole and this will give enough play for the valve to find it's own seating on the portface and lift off if needed.

[Tony MartyrParticipant @tonymartyr14488]

Thanks for this Jason

I rather feared it was something like your reply – but with only about 7 thou radial clearance between rod thread and hole the distance between the valve face of the cylinder and the centre-line of the valve rod is a 'bit critical'. The counter boore of 1/4" in the bck face must be the contain one of the locking collars/nuts.

Thank for your reply – Tony

[JasonBModerator @jasonb]

I don't think it would hurt to make the 1/8" hole slightly oval so the valve can lift more, you don't want so much side clearance as gravity will keep it at the bottom. The valve on my Fowler has the same two nut method but the valve is open backed

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