Stevens Model Dockyard Engine

[Chipmaster]

This afternoon I was given this old vertical model steam engine to restore, could the members identify it please?

CRHC1727 (2) by Andy, on Flickr

All the engine castings are brass or bronze.
The base is cast iron.
The bore is 1.978"
Stroke = 3"
Flywheel = 8.5" diameter
Overall height = 19"
The cheese head screws holding the cylinder cover are 5/32" x 32 tpi  Whitworth form = the Meccano thread.

IWQF3603 by Andy, on Flickr

IMG_4506 by Andy, on Flickr

IMG_4507 by Andy, on Flickr

IMG_4505 by Andy, on Flickr

IMG_4497 by Andy, on Flickr

IMG_4500 by Andy, on Flickr

And it's got a bad knock as can be heard in this video from my Flickr Album

IMG_4503 by Andy, on Flickr

Andy

[Jasonb]

Not one I could name but the two bands on the cylinder are similar to what Stevens's Model Dockyard tended to favour as are the tee section frames and they tended to cast in non ferrous.

It does not look like it is all from one set of castings as the bottoms of the standards don't really fit the base as they overlap and also at the top they look to have been pushed outwards to make them "fit" the base but the flanges overhang the cylinder and the crosshead looks too wide

Pump is an after thought as it that Vee pully stuck right at the end of the crankshaft. bearing pedestals also look crude compared when compared with the top half of the engine so may well also indicate it has been grafted onto that bed casting at some time.

[Chipmaster]

Thanks Jason, yes I reckon it’s a Bitza for the reasons you pointed out. I haven’t found evidence of Stevens cylinders as big as this one so far.
The pump casting  looks like a Stuart Turner boiler feed pump.
I can work on  this engine in between coats of paint drying on my Stuart Major.

Andy

[Jasonb]

I've got a reprint of their 1919 catalogue and the cylinders with the two bands were available in 1 3/4" and 2" bores though aimed at horizontal engines. The Tee section frames intended for marine engines went 1 1/2" and 2"but used plainer cylinder castings. So possible it was made up with a mix of castings.

[Alyn Foundry]

Hi Andy.
The flywheel looks familiar to me. Minus the counterbalance.

This Brass flywheel was recovered from the Uppingham school workshop and has been “ doctored “ for use as a pattern.
The date Jason has provided fits in with the era of the school’s activities.

  Graham.

[Chipmaster]

Thanks Jason and Graham.

After a little more cleaning the counterbalance on my flywheel can be seen to be a piece of lead wedged in between the spokes and blended in with the outer face of the flywheel.

  IMG_4533 by Andy, on Flickr

IMG_4535 by Andy, on Flickr

Andy

[Jasonb]

Funny enough I recently did similar to a Stuart 7" flywheel though I just bonded on some strips of lead with JB Weld.

What condition is the boiler in, ort is that just a water hopper feeding the pump that I can see?

[Chipmaster]

Morning Jason,

The boiler;

Welded steel construction, possibly ex gas cylinder going by the weight, horizontal water tubes, probably gas fired.

 NIIZ4751 by Andy, on Flickr

IMG_4512 by Andy, on Flickr

Condition;

The water level gauge is intact
IMG_4512 (2) by Andy, on Flickr

Foundation Ring....
IMG_4520 by Andy, on Flickr

Genuine A J Reeves & Co pressure gauge in need of repair
IMG_4517 by Andy, on Flickr

I don't intend to try it out.

Andy

[Chipmaster]

A couple of months later the consensus is that most of the engine is Stevens Model Dockyard and it needs a lot of work to sort it out. It knocks very loudly, the crankshaft is bent and the bearings are worn but it does run, I'll have a go but completing my Stuart Major has priority.

The crankshaft wasn't properly supported, one of the main bearings was in the wrong position because the void in the old cast iron base meant it couldn't be fixed in the correct position.

IMG_4561 (2) by Andy, on Flickr

I used a 1/4" thick brass plate to cover the old base and make a fresh start.

IMG_4672 by Andy, on Flickr

IMG_4739 by Andy, on Flickr

This enabled the main bearing to be moved between the crank web and eccentric.

IMG_4744 by Andy, on Flickr

The brass plate will improve the appearance.

IMG_4748 by Andy, on Flickr

However, it seems I will have to replace several parts to sort out the knocking, perhaps another crankshaft if I can't straighten the original. Here's a recent video of the engine running on compressed air. The first part of the video shows the engine at the outset then running after the brass baseplate was fitted. The knocking is terrible, I suspect the piston hits the lower cylinder cover but because of the way the engine was made there is no means to adjust for that.

 <a href="https://www.youtube.com/watch?v=N4k9T31Tw1k" target="_blank">http://www.youtube.com/watch?v=N4k9T31Tw1k</a>

Andy

[internal_fire]

I suspect the piston hits the lower cylinder cover but because of the way the engine was made there is no means to adjust for that.

Depending on the situation at the top end it might be possible to lower the standard a tad. Shaving the bottom of the feet could be difficult, but since you have added the brass base it should be quite easy to make a small recess under each foot.

Alternatively, the crankshaft could be shimmed upward.

Gene

[Chipmaster]

Thanks Gene, I'll try shims under the main bearings. 

Andy

[Michael S.]

Oh, I should have turned up the volume of the video before commenting on Youtube 😏.
Now I hear the knocking too.
What irritates me, however, is that the concentricity of the crankshaft is even. I mean there is a small stop, which I would assume when the piston hits the cylinder. The crankshaft should run jerkily.
If it's the piston, can you trim it from the bottom?

Michael

[crueby]

That kind of sound could also be slack in the bearing at either (or both) ends of the con-rod, or movement in the main bearing (less likely). If you turn it over by hand with no air pressure applied, you should be able to tell. With the crank horizontal, turn slowly one way, stop, and go back the other way. If there is a loose bearing, you'll feel/see that the piston doesn't move for a short part of the rotation back and forth. If it is hitting the cylinder end, you should be able to feel that too as the piston stops and the conrod/crank have to pull through the last of the turn at the bottom or top. If its hitting, can't be by much since it can make it around the turn.

[Jasonb]

Even a very worn big end bearing would allow the piston to come down a little further than it should. best to track down exactly where the problem is (problems are) before machining bits of metal off that you can't put back on.

[Chipmaster]

When I took the cylinder apart there was a lot of crud between the bottom cover and the underside of the piston but probably not enough to cause the knocking but it did seem worse at bottom dead centre.
This picture shows there is approximately 1/8" clearance at bottom dead centre.

IMG_4849 (2) by Andy, on Flickr

So I had a closer look at the crosshead, there was some slack in the bearing. After cleaning I could see that the crosshead had been sleeved.

IMG_4853 (2) by Andy, on Flickr

IMG_4854 (2) by Andy, on Flickr

The bodged soft brass sleeve was drilled out, it had been a forced fit. 5/16" o.d. and 1/4" i.d.

IMG_4857 by Andy, on Flickr

That should be easy to replace.

Andy

[Michael S.]

Then it's an easy fix.
I'm always amazed at what a small amount of play in the bearing causes a knock.

Michael

[crueby]

Great detective work, and not stopping at the first thing found is good, there are often several things stacked up!

[Chipmaster]

New bronze sleeve 5/16 od x 1/4" id fitted to the crosshead.

IMG_5111 by Andy, on Flickr

IMG_5112 by Andy, on Flickr

Followed by a new stainless steel piston rod 5/16 diameter with 1/4" BSF thread at each end.

IMG_5099 by Andy, on Flickr

IMG_5100 (2) by Andy, on Flickr

IMG_5120 by Andy, on Flickr

A new pin was fitted to the cross head and the engine turns over very smoothly at this stage

Flickr video
IMG_5113 by Andy, on Flickr

The excess thread might permit fitting a slim locknut if there's sufficient clearance under the cylinder cover.

 IMG_5125 by Andy, on Flickr

Next step will be replacement of the rusty valve rod.

IMG_5121 by Andy, on Flickr

Andy

[Chipmaster]

At each end of the cylinder there was evidence of a plugged hole, ex cylinder drain cocks I presume but it looks like the thickness of flange at the end of the cylinder has been reduced, what happened to this bitza - weird.

 IMG_5177 by Andy, on Flickr
IMG_5180 by Andy, on Flickr

Buffed up.

IMG_5185 by Andy, on Flickr

The gland for the valve rod had an M10 x 1 pitch, I reckon the 1/4" bore male end union from the hydraulic brakes of a car had been used and the female part had been soldered onto the valve chest.

IMG_5211 by Andy, on Flickr

As it was very worn I bought an M10 x 1 male brake blanking plug then drilled and reamed it to 1/4".
IMG_5227 by Andy, on Flickr


IMG_5228 by Andy, on Flickr

Here it is on a new stainless valve rod complete with a new half of the pivot.

IMG_5229 by Andy, on Flickr

Reassembled with brass dome nuts and given a whiff of compressed air.

<a href="https://www.youtube.com/watch?v=VNkfJWM_gGo" target="_blank">http://www.youtube.com/watch?v=VNkfJWM_gGo</a>

Buffed up it's looking better but there are still several issues to be corrected. The bent crankshaft is pretty bad and may have to be replaced if careful hammer blows don't straighten it. A new valve chest will be required because bodged/oversized holes around some of the studs have left almost no surfaces for the cover's gasket to seal against so it's leaking air at quite a rate.
It would be a bad idea to steam it with such a leak.

Andy


 

[Michael S.]

Hello Andy,
very nice old steam engine.
Maybe you can straighten your crankshaft on the lathe. I bend the end of the crankshaft in the right direction with my hand and check with the dial indicator. I wouldn't use the hammer.

Michael

[Jasonb]

It's certainly looking and running better than it wa sin your first post.

As to the crank, you know the saying " if in doubt, get the Stilsons out"