Anecdote – 3

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

A long time ago when I was in my college days there was a shortage of engineers in several different industries . To rectify matters the different industries started actively recruiting students and offering them attractive packages of bursaries for further studies , apprenticeships and guaranteed jobs with good salaries at the end .

Each industry offered a short industrial experience course for students to get some idea of what the work would be like . These courses varied from a quick look around , a lecture and a film to week long residential courses with extensive visits , lectures , films , lab work etc .

Being me I decided to go on the 5 day NCB sponsored Mining Engineer course .This was held at the Dept. of Mineral Exploitation at Cardiff University and on site at two collieries .

The academic bit was quite interesting but it was the site visits that I will never forget .

There was one long underground visit and several surface workings visits .

I’ll tell you about my experiences underground , which included hurtling straight down at nearly 30 mph in a cage not much bigger than a photo booth and crawling a very long way in a 4 ft headway , another day .

Todays story is about the power house at one of the mines .

Most Welsh mines originally had steam operated pit head gear but by my time some of these had been converted to all electric power . The one that I visited that day had been converted sometime in the 1950’s with an unbelievably motly collection of equipment all jammed in anyhow in the winding house and adjoining power house .

The actual winding motors were a tandem pair of big old fashioned motors which had to be ‘ driven ‘ ie run up to speed through a bank of starting resistors . Had to be a variable speed set up to suit the acceleration / steady speed / deacceleration profile needed for working the cage but I never worked out exactly how this was done and there was nobody knowledgeable to ask .

To call the starting resistors ‘resistors’ was not entirely realistic since most of them consisted of at most a few turns of plain copper bar wound around a white ceramic former . They were in a steel mesh cage but most of the mesh was as missing . Everytime the resistors came onto load they visibly changed shape and made quite a loud cracking sound .

Now for the power house itself .

Three phase power came in from the grid via a relatively modern sub station and on into the power house proper . Inside the power house I’ve never seen so many ways of potentially meeting a dreadful end as I did that day . Here are a few highlights :

(1) There was a bank of six man size mercury arc rectifiers going flat out . Each one was actually in a concrete blast cupboard with steel doors but all the doors were either open or fallen off the hinges – in the event of a failure you had a choice of being fried by UV , boiled alive by hot mercury , poisoned slowly or quickly by mercury vapour , electrocuted , burnt , lacerated with flying glass or just blown to pieces .

(2) All the switch gear consisted of Frankenstein style switches of enormous size and manual reset solenoid overload trips . They all had Ebonite handles and were mounted on huge Ebonite panels along with big old fashioned meters – some showing enormous current and wattage values . They mostly had arc quenchers that had burnt through and there was no operator protection at all .

Must have been a mixed AC and DC supply system to the whole of the mine and I assume that this lot was the DC section . Again there was nobody knowledgeable to ask .

(3) There were a couple of motor – generator sets and several big transformers there as well – all with open terminals and all in safety cages with most of the mesh missing . All the shaft couplings were wizzing around in the open air and big sparks flew continuously from one of the sets with commutator and brushes .

(4) Wiring consisted in one part consisted of open bus bars on insulators mounted in open steel trays mounted at head height . Other wiring was a mix of modern and very old rubberised canvas types with a bit of lead sheathed for good measure – all in terrible condition .

(5) Just to round things off there was junk everywhere , the roof leaked and the whole of the foor was awash with oily water .

Health and Safety ?? The whole place was so bad that I actually felt safer underground .

Regards ,

Michael Williams .

Edited By MICHAEL WILLIAMS on 31/01/2013 18:36:05

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

[TakeawayParticipant @takeaway]

Heaven – at our factory we had to start work so early I had to eat breakfast the night before. Every bloke who clocked in had missing body parts and us apprentices were worked so hard that at the end of a shift we didn't have the strength to light a Woodbine dogend. When I got home and complained to my dad do you know what he said: "Sheer bloody luxury son, when I was a lad I had to…………………………………………..!!!

[Ian S CParticipant @iansc]

The only contact I'v had with mining in the UK was when i was there in 1984, I spoke to some strikers, the ones in Sheffield knew what they were about, but the ones in Glasgowwere rent a mob no hopers, they were not miners, and had never been near a mine, and couldn't give a stuff about the miners. A bit different now aye.

My field trip was a weekend at RNZAF Base, Woodbourne, at the north of the South Island, a fully opperational servicing base, and home of the Boy Entrant School. We where flown north in a Handley Page Hastings C3 (a Mk not used by the RAF). The following year I enlisted in the Boy Entrant School, and next year we hope to have a reunion. Ian S C

[Michael GilliganParticipant @michaelgilligan61133]

Great story, Michael

Glad you survived to tell the tale !!

MichaelG.

[SpringbokParticipant @springbok]

I am not surprised by what you say that there was a shortage of engineers in the mines I am sure that most would have looked at that lot and ran a mile. prob 6 secs.

Bob

[Ady1Participant @ady1]

The old chap I talk to sometimes left the railways when they were nationalised because the money wasn't as good

His "Christmas holiday" was getting off early at 3pm on Christmas day

[BazyleParticipant @bazyle]

The mention of copper coils reminded me of our only school trip which was to Oxford University Physics dept. We were shown a magnet coil for their research into superconductors under magnetic fields which was a 9in diameter copper disc with a slit in it to make a 1 turn coil that could withstand the magnetic field that would try to uncoil it. Of course copper is not so soft under liquid helium. To use it they ran up a 1MW diesel generator and shorted it into the coil which stopped the generator dead and produced a massive magnetic field for just fractions of a second. The electrical switch was a bank of many 6ft square copper sheets covered in parallel wired OC35 germanium transistors which could each pass a whopping 3A.

After the tour we were left alone with a PhD student to tell us what doing a degree was about. He said the only thing he found useful from his 3 years was a quick extra course in surveying which qualified him for a holiday job holding a stripey stick.

[Brian WoodParticipant @brianwood45127]

At my first boarding school in the late 1940's, the school play each year used a dimmer wired up for the stage lighting.

This comprised of a large glass water tank, two copper sheets held to the sides and a wooden framed 3rd copper sheet that could be lowered or raised in the space between. The dimming was smooth, step free but this apparatus had open terminals and trailing cables and was operated entirely by hand. Even as a callow kid of 10 years old, I appreciated the dangers inherent in this thing. Clearly this isn't on the heroic scale of your other correspondents stories on this thread, but it was nevertheless a school filled with boys having an exploratory nature.

Brian

[Sub MandrelParticipant @submandrel]

My 'career field trip' was a geology focused visit to Dolaucothi gold mine near Rhandirmwyn. It was fantastic, entering adits and seeing roman waterworks. I cam back and made a (plastic) model of on of the chaldrons. We slept in the rifle range of a nearby private school and I came home with a couple of pocketfuls of empty .22 cartridges. Looks like they trusted the boys and didn't count them out and in, back in those days!

I went back with my wife a few years ago (that's where the big DSG lathe photo in my gallery comes from). It's national Trust now, and I was hugely disappointed – access was really limted to the mines themselves and somehow the interpretation totally failed to bring it alive in the way the abandoned site had been by our guides (from Cardif University IIRC) did back in about 1979.

At least the chaldrons were still there.

Neil

[Ian S CParticipant @iansc]

My first school trip was when I was in my last year of primary school in Hawks Bay, on the east coast of NZ's North Island, 1959, they took us to a tobacco factory for the main bit of the trip, we did go to a small plastics factory, and a cargo ship at the port. But can you imagine taking 30 or so kids to a Tobacco Factory today (we didn't get any free samples). Ian S C

[Brian WoodParticipant @brianwood45127]

Stub Mandrel's story of the gold mine visit and the DSG lathe he photographed there led me to take a look at his pictures. You may now know Neil what your mystery tool is and does; if not it is a Sawset, used for setting the teeth on woodsaws alternately along the blade by preset amounts dialed in by the round part of the tool.

They are largely redundant now with the widespread use of hard point saws that have been diamond ground, but any old time joiner would immediately recognise it. Eclipse were noted manufacturers.

 

Brian

Edited By Brian Wood on 02/02/2013 09:22:03

Edited By Brian Wood on 02/02/2013 09:22:56

[Brian WoodParticipant @brianwood45127]

Stub Mandrel's story of the gold mine visit and the DSG lathe he photographed there led me to take a look at his pictures. You may now know Neil what your mystery tool is and does; if not it is a Sawset, used for setting the teeth on woodsaws alternately along the blade by preset amounts dialed in by the round part of the tool.

They are largely redundant now with the widespread use of hard point saws that have been diamond ground, but any old time joiner would immediately recognise it. Eclipse were noted manufacturers.

 

Brian

Edited By Brian Wood on 02/02/2013 09:26:04

[Russell EberhardtParticipant @russelleberhardt48058]

My most vivid memory of an industrial vvisit from university was of one to Battersea Power Station in the mid sixties (before it was turned into anexhibition centre for so called art).

There were a number of three phase mercury arc rectifiers connected up as inverters with bright blue discharges looking like something out of a Frankenstein film. On one wall was a bank of enormous knife switches and next to them were a number of broomsticks with leather flaps attached for extinguishing the arc after you had opened a switch. I wonder what the HSE would make of that today.

After the visit I decided to go into electronics instead. It would be much safer!

Russell.

[Sub MandrelParticipant @submandrel]

Hi Brian,

Yes it was identified as a saw set for me -and then I found the original box, flattened and at the bottom of the old toolbox it was in! Funnily enough although hardpoint saws were available when I was a teenager I had actually set saws (with a simpler tool) and I have a proper saw file. I used it to reset a hardpoint saw as an experiment (without sharpening) and it did squeeze a fair bit of extra life out of it.

Neil

[Brian WoodParticipant @brianwood45127]

Hello Neil,

Now that's a useful piece of information, my biggest dread on old timber in particlular is running into a nail, it is usually death to hardpoint saws, afterwards they cut only on one side, if at all. I'll try and rescue the next one.

I have always junked them in the past, they are cheap enough. However, having sheared off the induction hardened edge, the rest of the blade makes excellent stock for flat, toughened, high carbon steel, good for thrust bearing washers for example.

Brian

[Sub MandrelParticipant @submandrel]

Hi Brian,

I always feel guilty junking old saws – now I have an excuse to hoard them

Neil

[Brian WoodParticipant @brianwood45127]

These stories of visits to mines remind me of a visit I made in the late 1960's to Markham Colliery near Mansfield. It is now closed and vanished below new development near Bolsover Castle alongside the M1

The abiding memory of that visit was of the constant and disconcerting sound of rock fall in the area left behind the coal cutter at the face where the hydraulic pit props, rather like large scissor jacks, were collapsed and moved forward to support the roof in the working area. I was assured all was well, but at about 1/2 mile underground it didn't fill me with confidence.

My late father told a story of the mine visit organised by the Rotarians in Leighton Buzzard, [come in old clothes] were the instructions. The bus was due to depart when the Chairman of the branch arrived late. He boarded the bus wearing buckskin shoes, cream buckskin shoes, a white suit complete with a white open neck shirt and colourful cravat. The whole ensemble was topped off with a light Panama hat!!

That was in the days when Colonel Blimp reigned supreme after the war and Pop, never one to be abashed by these pompous people, when questioned on 'what gongs did you get old man' on being told they needed a translation. 'What's a DDLM? Don't know that one'

He always took great delight in telling them 'Dan Dan the Lavatory Man'

Brian

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

There are often high compressive stresses in a coal seams and surrounding strata . In undisturbed ground everything is in equilibrium and nothing much happens most of the time . When the coal seam is cut into however the stress system becomes unbalanced and large forces are generated tending to force blocks of coal / rock out into the mine tunnel . Coal / rock can also move because of simple fractures faults . Net result is the same .

Sometimes a whole large block does actually fall out in an unsupported area but more generally the block moves a bit , the stress is reduced and the block knits back into surrounding strata and becomes relatively stable .

If Hydraulic supports are in use the release of stress and movement of the supported coal / rock puts very large loads into the support causing a very large increase in hydraulic pressure – more than enough to burst or buckle the support . To prevent this happening Hydraulic release valves are fitted – usually called convergence valves . These allow a short release of hydraulic fluid and pressure is kept in check . The unfortunate side effect is that the support drops a little . This is considered to be safer than losing all support by a burst cylinder .

I designed a convergence valve once – it wasn't easy .

Michael Williams .

[Brian WoodParticipant @brianwood45127]

Hello Michael,

Maybe our mine guide didn't go into detail of the technicalities of the hydraulic pit props, after all I am recalling a short visit from >40 years ago. I do remember he said that the props were constantly walked forward to support the working area around the coal face, the rock fall behind them was a controlled situation to fill in at the back of the slot being carved through the coal measure.

Now that you mention other rock movements, they did have to reshape the roadways as the work advanced and I also recall at Markham the biggest factor influencing that was actually heave in the road surface, trying to close the roadways from the bottom up. The level of geological heating down there was unexpected, there was hard frost above ground.

Not an industry I would have willingly worked in

Brian

[Gordon WParticipant @gordonw]

We were taken on a school trip to Boulby potash mine, was then the deepest lift shaft ? Huge underground tunnels with lorries running about. The machinery was taken in the lift and assembled in a big underground w/shop. Amazing place and am lucky to be old enough to have been able to do it. Later became interested in caving, sat under a mountain in total blackness you could sometimes hear the rock cracking and moving.

[Ian S CParticipant @iansc]

In the south west of New Zealands South Island, at Manapouri, a large hydro electric power sceme was built under the mountains. It was found thatthe workers suffered cuts etc from microscopic jets of water coming out of the rock. A friend of mine was one of the engineers on the site, and thought some of the rock would look good on his mothers rockery in her garden, so next time home he loaded up a trailer full, and went home to Christchurch, the rockery looked good…… until after the frosts in the winter, the water in the rocks froze and they exploded. Ian S C

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