The Unofficial Mamod and Other Steam Forum

Steve_S · Posted: Wed Apr 29, 2009 7:47 pm Post subject:

Nick, thanks for the pictures, that's excellent information. Now I know what I'm aiming for! It's interesting that the safety valve screws into the steam dome... I haven't seen that arrangement before. I'll need to try make a replacement steam dome out of something more substantial than lead. You've given me plenty to think about. A meths conversion might be the easiest option, but then again it might not burn well because there's no opening for hot air to flow upwards. It would really need a flue to pass right through the boiler to a chimney. That might be easy enough to arrange, and it wouldn't change the outward appearance. I'm just thinking aloud here! I'll also do some research into replacement electrical heating elements, though after hearing about yours I'm not optimistic. Thanks again for the pictures!

Steve_S · Posted: Mon May 04, 2009 9:53 pm Post subject:

I've made a bit of progress with the Weeden. The flywheel was loose on it's shaft and there was no obvious way of tightening it. In the end I secured it with an epoxy adhesive similar to araldite and it seems to have done the trick. I found that two of the flywheel spokes were cracked where they meet the rim so I dabbed a spot of adhesive on them too. The flywheel seems to have had a couple of severe knocks and is slightly deformed, but there isn't much I can do about that and it's not too noticeable. I've had to repair the steam pipe entry point on the top of the engine block, and I'll post some pictures of that tomorrow.

The mechanism of this engine is very simple... it's a single acting cylinder with a bobbin type slide valve driven by an eccentric on the crankshaft. (Incidentally, I've seen it stated in more than one place elsewhere on the net that this engine is reversible. Well, I don't see how it can be!)

I put it all together with a temporary brass collar on the end of the shaft in place of the Weeden pulley wheel (which needs some work) and tried it with steam provided by my E135.... and it ran very well!

The next job will be to sort out the pulley wheel, then I'll have to decide what to do about the boiler.

James · Posted: Wed May 06, 2009 11:08 pm Post subject:

Bugger me!! Well done, Steve!

That's grand! See, I knew you were the right bloke!
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WeedenSteam · Posted: Thu May 07, 2009 3:00 am Post subject:

(Incidentally, I've seen it stated in more than one place elsewhere on the net that this engine is reversible. Well, I don't see how it can be!)

Have you tried to spin the flywheel in the other direction? I have a feeling because it is a single acting cylinder it should work.
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Steve_S · Posted: Thu May 07, 2009 11:02 am Post subject:

The thing is that the position of the eccentric that moves the slide valve is fixed with respect to the position of the crank pin, so if the flywheel was turning the 'wrong' way the cylinder would be trying to exhaust when it should be pushing, and vice versa. To be reversible there would have to be two eccentrics 180 degrees apart, and some kind of adjustable link coupling them to the slide valve... as the Stephenson link does on a Jensen. I hope that makes sense.... I know what I mean!

Roly Williams · Posted: Thu May 07, 2009 12:24 pm Post subject:

Steve_S · Posted: Thu May 07, 2009 4:51 pm Post subject:

WeedenSteam · Posted: Thu May 07, 2009 5:31 pm Post subject:

If you turn the wheel forward so the cam for the slide valve is in the top position, then as you turn it further it moves the slide valve forward to allow the steam to enter.

If you turn the wheel in the other direction so the cam for the slide valve is at the bottom then turn it further it again moves the slide valve forward.

The slip cams are only necessary if the cylinder is double acting, I think.
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Roly Williams · Posted: Thu May 07, 2009 6:12 pm Post subject:

WeedenSteam · Posted: Thu May 07, 2009 8:09 pm Post subject:

But, in one direction the piston is moving forward and pushing the crank over top, in the other direction it is still moving forward but pushing the crank over the bottom.

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rangerssteamtoys · Posted: Thu May 07, 2009 9:23 pm Post subject:

My IND-X ( knock off empire ) which was very similar to that engine had a slip eccentric on it. It worked, so if that engine has it it should work too.
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Roly Williams · Posted: Thu May 07, 2009 10:00 pm Post subject:

Steve_S · Posted: Thu May 07, 2009 10:02 pm Post subject:

Precisely.

(This Weeden doesn't have a slip eccentric. The eccentric is part of the flywheel casting so it can't slip... it's angular position relative to the crank pin is fixed.)

WeedenSteam · Posted: Fri May 08, 2009 12:03 am Post subject:

If you imagine the crank and the eccentric in the same position the valve is pulled out in either diagram as the wheel is moved in the direction of the arrow.
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Roly Williams · Posted: Fri May 08, 2009 12:05 pm Post subject: