STEAM ENGINES AND WATERWHEELS

[Bodger]

what was the purpose of the curved spokes ?, did they give some flexibility to the pulley o.d. ?

[Stanley]

Interesting question Bodge. Many observers of curved spokes in early years thought that the extra length involved in making the curve gave greater leverage. Nonsense of course. The explanation was quite different and wholly practical. These are cast iron and due to the differential contraction between the boss and rim (where there was most metal and therefore slowest to cool) and the relatively light spokes, pressure could come on the spokes during cooling which distorted the casting or introduced cracks. Introducing a curve into the spokes gave them a small measure of flexibility. For the same reason, larger wheels were made in segments or with split bosses if the rim was in one piece. All these ploys gave the metal freedom to move and relieve internal stress. Subsequent machining trued the construction up. The last example I saw of this was when a modern foundry cast the external gear segments for the Quarry Bank Wheel. They got the allowances for distortion wrong and they had a slight discrepancy in the curve. I was consulted about this and agreed with Fred the resident engineer that the only way out if they were not to be scrapped was to machine them to as near truth as possible. They got away with it but you can never get the pitch quite right after such rectification. As Newton once said, "You can't chip to pitch!"
This relieving of internal stress went on for a long time. Various ploys were used to get over the problem. Some high quality castings needed quickly were soaked in a furnace bringing them up to dull red heat and then allowed to cool slowly in the furnace. These were often described as 'malleable iron' castings. Chairs for rail lines were so treated. Another ploy if there was more time was to do the initial machining and put the castings outdoors to age over perhaps a couple of years. At one time you'd see stacks of rusty castings in the foundry yard undergoing this process. The trick after ageing was to do minimal machining say on the ways on a lathe bed. One thing I noted many a time when reconditioning old steam valves to a close finish was that even though they had gone through many heat cycles, if you left the casting in the lathe over lunchtime after truing and went back to it there was still minute distortion in that short time after all those years.



Here's a good example of how it could go wrong. In 1949 when Roberts' at Nelson cast the new flywheel for Bishop House it was years since they had done a job like this and although it looks quite splendid on the pic, the geared jack wheel was out of truth and if you read Newton Pickles account in the LTP he tells how Roberts couldn't afford to cast another one as it would have bankrupted them so it had to be chipped in situ, a big job and never satisfactory. Even in the hey-day of casting, Musgraves got the gearing wrong on the big engine at Butts and it was a source of constant trouble till the mill closed. See the Calf Hall Minute books.

[Stanley]

The Butts mill engine in the 1930s. Note the size of the jack gear which was out of true. The vibration from it went right through the mill.

[Bodger]

A slight digress, the link refers to using conical drives on steam engine governors, see post 9, a method of controling cutting speed when facing large dias. on a lathe,look at post 17, a mechanical / electric version
http://www.practicalmachinist.com/vb/an ... ne-152662/

[Bodger]

Stanley, i guess you would have great fun with this on Barlick green !, post 37
http://img.photobucket.com/albums/1003/ ... nmower.jpg

[Stanley]

Leyland made steam lawnmowers as well in the early days.

[Stanley]

The original 12" steam main at Ellenroad. We had to replace it with 6" main pipes but for a long while I saved these pipes. I think they have been scrapped now. They were a wonderful example of what can be done by real experts in fabrication. The flanges were forged, so work out how they did that! I had a bloke at the site one day, an old boiler inspector, and as soon as he saw the pipes he knew they were made by Stuart and Lloyd I think at Corby.

[Bodger]

Heat the pipe end and swage them out while hot ?

[Stanley]

I was told they were hydraulicly upset while white hot and then finished in a lathe but how did they deal with the bent one? If they bent it afterwards how did they keep it circular? Lots of puzzles!



I got Norman Sutcliffe to cut the end off the vandalised Jubilee boiler and put it in the boiler house at Ellenroad as an exhibit... Just like that!

[Bodger]

thinking aloud, clamp the bend in a jig on a boring machine table and use a outside turning tool on the machines head ?

[Bodger]

roughly what i was thinking about
http://en.wikipedia.org/wiki/File:Fotot ... nbauer.jpg

[Stanley]

Big jig, big lathe!



Boring the valve seats on a large HP cylinder at Brown and Pickles.

[Stanley]

Boring a large air pump body at what was then Henry Brown and Sons at Wellhouse works about 1900. If you look carefully you can see that the cut is almost 1/2".
You can see the steam engine that drove the shop when the main engine was stopped just behind the boring machine.

[Stanley]

Once a year the boiler had to be emptied for cleaning and inspection. Bancroft boiler being blown off in summer 1977.

[Stanley]

Once the pressure had been relieved the remaining boiler water was blown down into the drains. Here is the yard at Bancroft in 1976 during blow down. The superheated water flashed into steam in the drains and filled the yard with steam for about twenty minutes.

[Stanley]

The boiler at Ellenroad with all the brickwork stripped off it. The two boiler-suited figures are trainee boiler inspectors from Vulcan. The regular inspector sent them down to get experience. They came to me to have the boiler explained to them, they'd never seen a Lancashire boiler before. I rebuilt the brickwork my way and if you go to have a look at it you'll find it has worked well. The only boiler I know where the brickwork hasn't cracked. The side wall goes up to the roof in one lift.

[Stanley]

The essential gauges on Bancroft engine. Steam pressure, vacuum and the balance between the LP and HP cylinders.

[PanBiker]

Aren't a good set of gauges aesthetic pleasing? Can't beat a bit of polished brass and glass.

[Stanley]

Pressure and water gauges on the boiler front at Bancroft Shed. Just as important as the engine gauges.

[Stanley]

The lubricator on the HP cylinder at Bancroft. Made By Kirkhams of Lark Street Bolton it had to pump oil in at greater than steam pressure, that is about 200psi.

[Stanley]

One of the four pumps on the Bancroft engine that circulated the oil back to the pillar bearings on the flywheel and second motion shaft bearings. Once the oil had been used it was pumped back up into the aquarium lubricators on each bearing. Scotch yoke and ram pump on these but some had gear pumps. They were driven by a small cotton rope drive from the shaft they were serving.

[Stanley]

The aquarium lubricator on the HP side flywheel bearing and eccentrics of the Bancroft engine.

[Stanley]

The big aquarium on the HP side flywheel bearing at Ellenroad. Amazing that they survived when the engine housed was derelict.

[Stanley]

Steam engines relied on good accessories. A Hopkinson 6" junction valve on the boiler at Ellenroad. Hopkinsons of Huddersfield made the best valves and boiler accessories in the world. Knocked out by cheaper imports but nowhere near the same quality. A reconditioned Hopkinson valve beats the modern competition hands down.

[Stanley]

The top of the Lancashire boiler at Bancroft Shed. The valve with the weight propped up on bricks is the Hopkinson high steam/low water valve that was a back-up for the dead weight safety valve at the far end. This was the valve that I used to let the steam off the boiler for annual shut down by propping the weight up as you see here.