Benson’s Vertical Engine

[Bodger BrianParticipant @bodgerbrian]

I’m picking up the construction of the Benson’s Vertical Engine (serialised in ME Vol 177) which I started many moons ago but for various reasons, didn’t finish.

I have a question regarding the dimensions of the slide valve. As far as I can see, the height of the valve is not shown on the drawing but my limited knowledge of the finer points of steam engines suggests that it should be the same as the thickness of the steam chest (10mm), as apart from the valve rod there is nothing to prevent the valve lifting from the port face under pressure.

However, having cut the 2.6mm & 3.0mm slots to a depth of 8mm (10mm – 2mm, the thickness of the base), I’ve realised that the result of my efforts don’t visually match the drawing in that the slots in the latter look a lot shallower.

I’m fully aware of the oft-used phrase ‘do not scale from the drawing’ but am I making a wrong assumption about the overall height?

Brian

(Apologies for the font size but I can’t find how to change it!)

 

 

Edited By Bodger Brian on 17/11/2017 19:53:39

Edited By Bodger Brian on 17/11/2017 19:54:49

[Bodger BrianParticipant @bodgerbrian]

Slide valve dimension

[JasonBModerator @jasonb]

You want the valve to be a bit less than the depth of the cavity so that it can lift off the port face otherwise a build up of condensate could cause hydraulic lock, the steam or air pressure will hold the valve to the port face When I made my 50% larger version I made the vale 0.500" high in a 0.562 deep valve chest. So in your version an overall height of 8.5 or 9.0mm will do.

 

 

Edited By JasonB on 17/11/2017 20:48:25

[Bodger BrianParticipant @bodgerbrian]

Thanks Jason.

It’s good to know that I can take a mm or so off the height without any ill-effects.

Brian

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