The middle is the exhaust. The valve should connect each end of the cylinder connects each end of the cylinder to the exhaust in turn. The Valve should also expose the opposite port to the steam chest at this point. If the centre port was connected to steam pressure then the valve would be forced off its seating.

Have a look at

**LINK**

regards Martin

Mike, it sounds like your valve may have a hole right through it? It should only have a hollow cut out on the lower face. In these diagrams the valve face is on the left with the cylinder holes at top and bottom, exhaust in the middle. The outside of the valve chest isn't shown, but the steam/air basically surrounds the yellow valve

You can see how, if the valve is moved downwards in each case it will allow steam into the upper cylinder and allow the bottom valve to exhaust. When moved upwards the opposite happens.

The valve should never move far enough for the central exhaust port to be exposed, only far enough to open one cylinder to exhaust whilst the other is open to steam..

Edit: a photo of your valve would help.

Edited By Neil Wyatt on 01/12/2015 20:01:55

Out of interest how can you tell?

Neil

hi Neil,

in the Norden drawing the exhaust cavity in the valve is less than the inside edges of the steam ports. this would result in an extremely sluggish and lumpy working engine whether marine, stationary, traction engine, or loco. the exhaust cavity should be 'in line' with these edges. if it is slightly greater this is what is known as exhaust clearance, which was used in some steam loco in fullsize with restricted passages and which were otherwise 'constipated' for fast running.

cheers,

julian

Julian, I'm surprised.

I designed it that way as it's meant to run very slowly and on air – prototypical speed is no more than about 100rpm. This is a challenge to achieve with a small flywheel and a single cylinder.

You rightly point out that exhaust lap is bad for fast running engines, but it is normal to have exhaust lap in slow running engines.

Also, my intent was for an engine optimised to run on air, hence the extended admission period, following the thoughts of Tubal Cain on this subject.

But the proof of the pudding is in the eating – I have a video of it running very smoothly on air at under 60 rpm, which was the objective. As I'm sure you know, it's much harder to get an engine to run smoothly on air than steam.

In short, Norden is designed to run on steam or air are low speeds and to do so optimally it requires a different valve to locos.

Neil

Mike,

One way around your problem would be to have some practical help from a forum member who may happen to live nearby and is willing to help. I looked at your details to find you don't have a public profile so anyone clicking on your name has no idea where you live. Just an idea of your geographic position may help.

There are many reasons why members don't give private details. Maybe you could give more details to (say) Neil who could then put interested members in touch with you.

Regards

Barry

who lives near Plymouth if this is a help.

Ah, just seen your pics (posted whilst I was composing). You have the valve in upside down. The fully enclosed face should face the cylinder.

Martin

and without appearing to be too critical the sliding faces of both the slide valve and the valve chest need to be flat and smooth to get the seal you need. In the 1st and 2nd picture it looks as if the valve chest seat need some attention – it doesn't look very smooth in the photograph.

Also ensure when the slide valve is in the correct position as suggested by Martin, that the steel slide valve rod isn't stopping the slide valve from making contact with the valve chest surface. This could happen if the steel rod and the gland it runs through are not aligned correctly. 

Barry

Edited By Barry Q on 02/12/2015 10:12:38