The Steamboating Forum

I'm need some technical help on a single cylinder bottle style steam engine with a "rotary valve". I have attached two pix to lead you to the problem area. I have never run the engine though it turns smoothly enough. The immediate problem I saw was the exhaust. The female threads in the exhaust appeared to be broken and the rotary valve itself was nearly flush with the end if the threads
I took the actuator loose from the opposite end of the valve chamber and pulled the valve itself. I could see the exhaust had plenty of threads for a close nipple. On the actuator end there was a brass ring to compress the packing and a threaded outer cap to compress the brass packer ring. The problem is, there is no shoulder or packing on the exhaust end for the valve to thrust against. Something is missing.
Barring someone on the forum having input on the design of the missing part or parts, I will put a matching brass ring with a chamfer to match the chamfer on the end of the valve. However, the only thing for the brass ring to back up to would be a nipple screwed into the female coupling threads on the exhaust. I would like to add some packing on the exhaust end but there is no shoulder on valve or in the bore to back it up. therein is the design delimna. it seems the valve will leak at the exhaust end. even if the valve seats well to the brass ring, (taper to taper) there will no seal on the OD except the close fit of the valve to the bore.

Perhaps you could take another swing at adding those pics.?

- Bart

yes i am having trouble reducing their size.
thanks

wsmcycle wrote:yes i am having trouble reducing their size.
thanks

I've taken to putting the photos in a Google album and sharing that; it works well and I'm not limited to 128k, and I can include videos, etc.

- Bart

Download Pix-resizer. Just remember to refuse all the rubbish it tries to slide by you. It's freeware and is so easy to use.

Not sure about them Apples though.

Mike Rometer wrote: Not sure about them Apples though.

On a Mac, ou can resize photos from the 'preview' application, which is the default picture viewer. It's under the 'tools' menu.

- Bart

Windows has a free picture resizer as part of the "Windows essentials" package.

-Ron

Here is a snipped pic of the exhaust end of the valve. The valve end can be seen flush with threads of the exhaust fitting.

I think that the valve design will force the valve to seat against whatever is in the rear... If I understand the design correctly, the the size of the rotary stem is small compared to the area of the exhaust, so there will be a net force due to the boiler steam pressure acting on the valve body, moving it towards the exhaust port. Perhaps there's supposed to be a tapered seat that the valve works against?

- Bart

thanks Bart

even in the static condition, the packing nut on the actuator side pushes the valve against the exhaust side. See the little taper on the end of of the valve? My plan is to make a brass ring with a matching taper and an OD to fit snug in the valve barrel. i am going to shorten a close nipple to receive a coupling that jams against the exhaust face. you can see in the pic that half of the outer thread has broken off.
its a pretty interesting design. i don't know if it is efficient. Have you seen something like it? The round valve itself would be a chore to make long ago but it is simply a D valve rolled in a circle. The port casting could not just be milled through. I have not removed the piston yet but the porting in there should be challenging to reason out.