Northumbrian – Steam Chest Dimensions

[doubletopParticipant @doubletop]

Part 8, page 134 drawing 31 has the dimensions of the aperture missing.

 

I’ve scaled off the dimension that are provided, some of which are clearly drawn incorrectly (the 1/4″ ends). Assuming a common fraction of an inch I make the missing dimensions around 17/64″, 36/64″ and 11/64″. 36/64″ is 9/16″ and that’s the width of the slide valve, which maybe what was intended?

 

Can anybody confirm please?

 

Pete

[doubletopParticipant @doubletop]

Missing dimensions (again)

[Joseph RamonParticipant @josephramon28170]

The slide valve should not need the insides of the valve chest to keep it in alignment.

 

Making the steam chest aperture as big as possible will be beneficial, as it reduces the ‘wiredrawing’ effecty when most of teh steam for teh cylinder has to come out of the pipes.

 

Joey

[doubletopParticipant @doubletop]

I’ve just been on the phone to Peter Harmon at GLR, about something else, and he gave me the dimensions 1/4″, 9/16″ and 3/16″ . The valve width dimension is also 9/16″ and the write up suggests something along the lines of “make the valve just under 9/16” implying the valve uses the steam chest sides as guide for the valve but elsewhere the writeup says that the gland nut acts as the guide.

 

That said, and as Joseph suggests, my casting will need to be machined bigger than 9/16″ to be able to square up the cast aperture .

 

Pete

[Author]

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