Why do coal mines always have two ...... (1 Viewer)

[Spriddler]

Two cages wind from the same drum one up one down ?

Yebbut why would you have the wheels turning in opposite directions as each wheel would then need its own individual axle. The actual wheels aren't themselves powered; they are merely slave wheels being turned by the friction of the cables around them. If both wheels shared a common axle the lowering cable could be the one paying out from under one wheel and the lifting cable on the other wheel would be fed at the top of the wheel. Thus with both wheels rotating in the same direction and on a shared axle there would be only one axle and fewer bearings required.

Don't know but it could be to speed up the load/unload time. One at pit bottom being loaded while the other is pit head being unloaded.
It may be the way the winding drum gearbox works.... A bit like a differential, if jacked up one wheel will turn clockwise, the other anticlockwise. Substitute wheels for drums.

That's a point. A gearbox seems an unnecessary complication when it could be eliminated by simply feeding one cable to the top of of one winding wheel and the other cable to bottom of the other wheel as mentioned by Steve and Denise and Landy Andy

Spriddler your question interested me to the point that I searched on the internet. The answer is surprising - see the cut and paste below:-


So basically, you have one winding wheel per shaft, as there has to be two shafts by law!

.

Dibnah was a mate of my Dads from teenage years (scrap man) I remember going his place a few times as a kid and meeting him at various steam rallies etc. (pubs and beer tents mostly) me dad said he was tight as cramp.

I think he had a working model in his yard when he got round to finishing it years later (if he did finish it)

He intended to dig a 150' deep shaft but never finished it as the local Council prevented him from digging more than about 10'.

I think your answer is like steve and denise said, 2 cable runs operating from one drum, 1 up 1 down, makes Physics and cost/engineering sense

BBC - History - British History in depth: Winding Gear Animation

Inside this mechanism of the industrial age

www.bbc.co.uk

Like a v twin engine

Yes, I did see that clip and website for the Nat'l Mining Museum at Caphouse in my nerdy searches but the two wheels appear to be directly above one mineshaft. Surely they wouldn't have dug a second shaft right next to the first one which would make both shafts at risk of collapsing/subsidence? Plus there' d be little escape advantage if the bottom end of the main and the 'rescue' shafts were adjacent to each other.

Thanks too, to grasscutter and LARRY99 for their added info.

As you will have guessed I'm a bit nerdy about these engineering things and the fascinating history of the first Industrial Revolution (c1740 to 1850) and have spent many weeks visiting the museums and sites in the Black Country and around Ironbridge, plus the Cornish mining areas and historic buildings housing steam powered water and sewage pumping engines and weaving mills.
If anyone with an engineering interest and wants to pass some lockdown time there's a superb but non too techy film on the design and construction of the Iron Bridge here:


And for the engineers and fettlers (O.K. 'Nerds') among us there's another engineering riddle which should be simple to understand but which has taxed my brain. It relates to a surprising (?) feature of ball and roller bearings which I'll put in a separate thread.
(Bet you can't wait!).

 

[Steve and Denise]

Yebbut why would you have the wheels turning in opposite directions as each wheel would then need its own individual axle. The actual wheels aren't themselves powered; they are merely slave wheels being turned by the friction of the cables around them. If both wheels shared a common axle the lowering cable could be the one paying out from under one wheel and the lifting cable on the other wheel would be fed at the top of the wheel. Thus with both wheels rotating in the same direction and on a shared axle there would be only one axle and fewer bearings required.


That's a point. A gearbox seems an unnecessary complication when it could be eliminated by simply feeding one cable to the top of of one winding wheel and the other cable to bottom of the other wheel as mentioned by Steve and Denise and Landy Andy


.


He intended to dig a 150' deep shaft but never finished it as the local Council prevented him from digging more than about 10'.


Yes, I did see that clip and website for the Nat'l Mining Museum at Caphouse in my nerdy searches but the two wheels appear to be directly above one mineshaft. Surely they wouldn't have dug a second shaft right next to the first one which would make both shafts at risk of collapsing/subsidence? Plus there' d be little escape advantage if the bottom end of the main and the 'rescue' shafts were adjacent to each other.

Thanks too, to grasscutter and LARRY99 for their added info.

As you will have guessed I'm a bit nerdy about these engineering things and the fascinating history of the first Industrial Revolution (c1740 to 1850) and have spent many weeks visiting the museums and sites in the Black Country and around Ironbridge, plus the Cornish mining areas and historic buildings housing steam powered water and sewage pumping engines and weaving mills.
If anyone with an engineering interest and wants to pass some lockdown time there's a superb but non too techy film on the design and construction of the Iron Bridge here:


And for the engineers and fettlers (O.K. 'Nerds') among us there's another engineering riddle which should be simple to understand but which has taxed my brain. It relates to a surprising (?) feature of ball and roller bearings which I'll put in a separate thread.
(Bet you can't wait!).

When people say SHAFT they mean the hole in the ground ie 2 shafts means 2 holes.
Each hole ie shaft has 2 cages in it as one goes down the other comes up ( in the same shaft)
The pit head wheels are not on a fixed spindle/ shaft hence they go in opposite directions.
I hope this helps I am not being clever but two different SHAFT meanings

 

[Spriddler]

When people say SHAFT they mean the hole in the ground ie 2 shafts means 2 holes.
Each hole ie shaft has 2 cages in it as one goes down the other comes up ( in the same shaft)
The pit head wheels are not on a fixed spindle/ shaft hence they go in opposite directions.
I hope this helps I am not being clever but two different SHAFT meanings

Ah, so the two cages are side by side in the same shared shaft. Yep, I've got that.

Therefore, does that mean that if each cage has its own independent wheel, spindle and cable which are not connected with each other at the top of the tower then in order to enjoy any counterbalancing advantage between the weight of the descending cage and the weight of the upcoming cage it must be gained at their common-to-both cable drum somewhere at ground level in the engine house and not up at the wheels' spindles?
I suppose it means that every time either cage cage comes up or goes down the other must ascend or descend in unison even if empty
Sorry if I'm being a bore/naïve.

 

[jockaneezer]

The large wheels you see on the pit head will share the common, fixed axle, but both wheels will be fitted with their own bearings at their centres, allowing them to turn independently of each other, a bit like a simple axle on a pony trap.

 

[Gooney]

Yebbut why would you have the wheels turning in opposite directions as each wheel would then need its own individual axle. The actual wheels aren't themselves powered; they are merely slave wheels being turned by the friction of the cables around them. If both wheels shared a common axle the lowering cable could be the one paying out from under one wheel and the lifting cable on the other wheel would be fed at the top of the wheel. Thus with both wheels rotating in the same direction and on a shared axle there would be only one axle and fewer bearings required.


That's a point. A gearbox seems an unnecessary complication when it could be eliminated by simply feeding one cable to the top of of one winding wheel and the other cable to bottom of the other wheel as mentioned by Steve and Denise and Landy Andy


.


He intended to dig a 150' deep shaft but never finished it as the local Council prevented him from digging more than about 10'.


Yes, I did see that clip and website for the Nat'l Mining Museum at Caphouse in my nerdy searches but the two wheels appear to be directly above one mineshaft. Surely they wouldn't have dug a second shaft right next to the first one which would make both shafts at risk of collapsing/subsidence? Plus there' d be little escape advantage if the bottom end of the main and the 'rescue' shafts were adjacent to each other.

Thanks too, to grasscutter and LARRY99 for their added info.

As you will have guessed I'm a bit nerdy about these engineering things and the fascinating history of the first Industrial Revolution (c1740 to 1850) and have spent many weeks visiting the museums and sites in the Black Country and around Ironbridge, plus the Cornish mining areas and historic buildings housing steam powered water and sewage pumping engines and weaving mills.
If anyone with an engineering interest and wants to pass some lockdown time there's a superb but non too techy film on the design and construction of the Iron Bridge here:


And for the engineers and fettlers (O.K. 'Nerds') among us there's another engineering riddle which should be simple to understand but which has taxed my brain. It relates to a surprising (?) feature of ball and roller bearings which I'll put in a separate thread.
(Bet you can't wait!).

Nice to see the Pork Pie shop in the background, I remember having a couple of pies from there. Probably the nicest I’d ever tasted at the time.

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[Steve and Pam]

Each wheel has its own axel, 2 wheels, 2 axels, 4 bearings.

 

[Spriddler]

Well that's sorted that out then.
Thanks all (and relax as I'll go quietly away now to continue work on my amazing design for perpetual motion).

 

[Steve and Denise]

Well that's sorted that out then.
Thanks all (and relax as I'll go quietly away now to continue work on my amazing design for perpetual motion).

Glad you got it, you were there but hadyour shafts in a muddle

 

[LARRY99]

There were Two of these , as you can see they were actually known as sheaves

 

[LARRY99]

As you can see from the picture above the groove that the steel multi strand cable/rope is wide ,the cable was about 4/5” diameter
now some shafts (hole in the ground) could be up to 1000feet deep and over time the steel cable would stretch, so the large dial in the winding house would have new marks placed on it to say when the cage was in the correct position for loading or unloading

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[pappajohn]

Contrary to what people think air is not blown down a coal mine.
It is sucked out on the upcast shaft.

Not at Boulby mine it isn't.
Air is brought in from the man/materials shaft via three 12ft diameter, 3000 horsepower each fans near the man shaft bottom in their own building.
At the end of your shift, in winter, the 3600ft ride up is absolutely freezing cold as air is pulled down the shaft. It didn't help the shafts were in permafrost to keep them stable.
The air then exits via the 'payload' shaft at a temperature well in excess of 100°f.

 

[pappajohn]

now some shafts (hole in the ground) could be up to 1000feet deep and over time the steel cable would stretch

I speak from experience.
On the way down if the winder operator was a bit enthusiastic on the brake at the bottom the cage could oscillate up to around 10ft in each direction due to the wire cable stretching under the weight of two decks of men, the cage itself and the weight of the 3600ft of 3" cable itself.
Terrifying the first time it happens.

 

[Spriddler]

A digression whilst on lifts......
A manufacturer customer of mine in Hamburg had a 5 floor building with a novel and unmanned continuously operating lift system.
There were lift cabins attached to a couple of vertical rods which raised and lowered each cabin by just one floor up or down dependant upon its phase when you got in. It moved fairly slowly and passengers had to step smartly into a cabin then step out smartly as it reached the next floor and step smartly into the next cabin if wanting to go further up (or down) to another floor and so on, progressing by just one floor floor at a time. It sounds a bit iffy but it seemed to work safely enough although I can't imagine that H&S regs would allow it now.

 

[grasscutter]

Not at Boulby mine it isn't.
Air is brought in from the man/materials shaft via three 12ft diameter, 3000 horsepower each fans near the man shaft bottom in their own building.
At the end of your shift, in winter, the 3600ft ride up is absolutely freezing cold as air is pulled down the shaft. It didn't help the shafts were in permafrost to keep them stable.
The air then exits via the 'payload' shaft at a temperature well in excess of 100°f.

I’ll vouch for how cold a shaft can be-in winter.
One of our jobs was to monitor with a camera the meeting point of the skips whenever they increased the ventilation in the shaft.
The skips were travelling at 60 feet per second and carrying 12 tons of coal. An increase in ventilation could occasionally cause the skips to start slightly turning. Any collision at this speed would be catastrophic.
To fit the camera we were lowered down on top of the skips, chained to the point where the winding rope was attached to it. A small platform was pushed out to the shaft wall where the camera bracket was placed.
Fixing that camera onto the bracket was one of the scariest things I have done. It was like being in an arctic wind tunnel during the winter months. These shafts were often 1000 metres deep.