Antique Steam Engine from Doorknob

heres a photo of the small hole, the notch can be seen here too, and in some of the photos from above I posted earlier, it turns out

Hi Michael, maybe there is an adjusting screw for something in the hole. The notch could just be an alinement mark, or possibly for a C spanner if that section is screwed in.

Regards Nick.

Hi Michael, looking at the photos again, that notch looks to be in line with the bush without anything in it. Perhaps there should be a rod down from the bush to a lever, that would be operating a spindle that goes in the hole and controls the valve gear and the notch would be for the rod to clear.

Regards Nick.

Edited By Nicholas Farr on 17/05/2019 19:27:27

Yeah I thought that too but I can’t see how anything connected in line with the notch wouldn’t interfere with the crank arm?

I wondered if there's a second missing or hidden crank that should be mounted coaxially on the same axle as the main crank. Like the hour and minute hands, a clock maker might think of that as a cunning way of passing an up-down stroke to a valve under the piston. The valve? rod might move safely in the slot behind the rotating crank.

The plate with two screws might cover access to the valve gear.

Dave

Edited By SillyOldDuffer on 17/05/2019 21:58:23

Hard to tell what some mechanically illiterate journalist was trying to say 100 years ago. But, that small boss with the hole in it on the cross-head does look sort of needle-ish size. But, it obviously is not designed to allow whatever fits in it to pivot in the manner of the other two rods connecting to the crank arm and crank gear. Whatever fitted in there, if anything, would have had to run in a straight up and down motion. Which matches with the small notch cut in the brass flange directly below it, possibly for clearance of whatever "needle" went up and down there.

But then what did it do? Sure looks tight for space in there for any kind of crank arm or eccentric to operate behind that existing crank arm. Possibly a small disc or crank sticking out that mystery hole below the crank, which was pushed in one direction by the descending "needle" from above then returned somehow to position by being caught by the rotating main crank arm? All getting a bit Heath Robinish but have you ever seen inside an old clock?

What diameter is the doorknob? Just trying to get a better idea of the scale of all those tiny bits.

One thing you could do is take that filler screw out of the "boiler" (doorknob) and connect up a piece of plastic tubing etc and try blowing in there while rotating the flywheel. You should be able to feel if any valve action is going on inside that large cylinder by internal means that we can't see from the outside.

Other than that, very careful disassembly and inspection would be the only way to figure out how the valve gear works and how it might have been operated. That really should be done by someone with experience in small model or clock making work. It would be a shame to have such a gem damaged by inexperienced "wrenching".

Have any of the 3D CAD enthusiasts started modelling this machine yet ?

... It would seem an ideal subject.

MichaelG.

Hi, what about a rack and pinion arrangement instead of a lever. Is the plate with the two screws complete or has something broken off it perhaps? as the bottom edge doesn't look as straight and neat as the top.

Regards Nick.

Hi Sorry for the delay replying. The doorknob is about 2 inches diameter, not a big doorknob at all.

I removed the screws from "the plate with two screws" (carefully!) hoping the plate was simply a cover but the crank passes through it so the screws went back in before anything got bent.

I removed the old brasso marks with a turps-based cleaner and it doesn't look to me as though anything around that area is missing. I think the area behind the crank arm on that side (without the flywheel) is too tight for a coaxial gear, and the thing you can see in the photos is a tiny pin that is fastening the crank arm to the crank, or rather wedging it tight against the end of the crank.

The small lever under the main cylinder rotates on a wedge shaped pin; it doesn't seem to me to be made for frequent movement, or it would be on a cylindrical shaft. The range of motion is quite wide - it moves from about 20 degrees past vertical towards the centre of the engine, down to horizontal outwards. So I'm inclined to agree with the idea that it's some kind of relief valve. But I'm no expert! The end of it doesn't look broken to me but shaped to allow a fingernail or similar to pull it back down.

I like the idea of using air to get a feel for the operation. I am still looking for a piece of tubing that will fit the filler hole!

Maybe the end of a plastic pen body carefully held into the filler hole would suffice for "tube"?

Keep us posted.

That might work, I'll give it a go!

Now there's no evidence of a coaxial crank I've gone off the idea in favour of this suggestion:

The missing 'needle eccentric' connected via the notch and behind the crank to a lever mounted in that mysterious hole.

The needle might have been ornamental, adding to the interest of the engine with more movement. Inside the engine is a dual valve that controls when steam is admitted to push the piston whilst at the same time allowing the other side to exhaust. The engine won't run without a properly timed valve. If the engine runs without the needle, the real valve gear must be inside. Might be helpful - an ornamental needle waggling a fake lever is easily replaced.

I'd be very wary of stripping it down. I wonder is a friendly vet would x-ray it for you?

Difficult to value, it's an attractive antique with engine collector appeal. I've seen much more basic model engines with £800 price tags.

Given what you've found about Richard Westerman, I think he made this item for display in his shop and at exhibitions. It shows he was skilled, imaginative and capable of attractive work in miniature. That chuffing away would have made him more interesting and memorable than other clock-makers - good advertising.

Dave

quick update: I tried the pen idea and although it is not quite small enough to fit in the filler hole i was able to cover the hole and apply some air pressure to the boiler. I promptly figured out that the steam inlet valve/tap (below the cylinder) is closed, and it is not turning with a moderate amount of pressure.

I also blew into the exhaust and got some movement at the flywheel (no more than half a stroke of the piston I would say) and also a little movement if I blew into that small hole near the crank.

But the question now is how best to open the steam inlet. I wanted to check here before proceeding - what is a good penetrating oil to use, if any?

WD40 might help. It's quite possibly a tapered plug cock so applying a little pressure from the rear to unseat the taper might help, but I'd be very, very careful.

Hi, maybe a little Viakal or other limescale remover, using something like an eye dropper or a pipette may help loosing the valve/tap up.

The illustration that SOD has made with his red line, is the sort of idea I had in one of my earlier posts.

Regards Nick.

Thanks for the tips. I'm wary of inadvertently (breaking it!) cleaning it or leaving a deposit behind, I know wd40 can leave a residue so just wanted to check that wasn't going to harm the brass or clean it up too much.

Apologies Nick, I should have given you full credit because it was your idea I'd picked up on. I typed "this suggestion" instead of "Nick's suggestion", my bad.

My contribution was the clarifying picture and the suggestion that needle and lever may be ornamental.

Dave

Hi SOD, no apology required, I wasn't having a dig at yourself, just pointing out that you had shown what I meant as I wasn't sure if Michael fully understood my idea and I think you made it clearer to everyone.

Regards Nick.

I'm not convinced on this exact set-up, but rather something similar but different, for several reasons. One being that the stroke of the cross-head is significantly longer than allowed by the small crank in red. In fact it would be the same dimension as the main crank, which obviously would clang into the main crankshaft. The other being that there is no facility for the "needle" to pivot at the top, as would be required in a crank and rod type situation. The notch in the brass flange where the needle would run tends also to indicate it does not move from side to side.

I'm thinking there must have been something that allowed the "needle" to move straight up and down. So something more like a pushrod pushing a lever, in effect a rocker arm, without the two being firmly joined. Or perhaps a short crank arm as shown in red but the pushrod passing though a loose hole in the end of it, with two collars on the pushrod that allow it to move the crank arm a short distance at the end of each stroke, but slide through without moving the crank until the other end of the stroke. You thus have a lost-motion linkage in effect. So it provides a sort of "switching" motion at TDC and BDC rather than a continous cranking motion. This would be consistent with switching the valves from open to closed and vice versa at the end of each stroke, as required for a single-acting cylinder.

Just a thought.

Hi Hopper, yes I was aware of the restraints that a lever would have, but thought that maybe a curved one might accommodate the problem. I hadn't thought of the push rod solution, but I think that your solution is more likely to work with a lever and of course the collars can be adjustable on the rod to get the timing correct. A mechanical version of a flip/flop.

Regards Nick

Edited By Nicholas Farr on 22/05/2019 09:01:05