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Modeling 'The Gilpin Tram' - pt.I
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 Posted: Sun May 15th, 2016 02:10 am
   
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elminero67
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Michael-I second Keith on your insight.

Keith-thanks for sharing, great stuff as usual. As a footnote, in all of my years of travelling to old mines, I have never seen a Cornish pump in situ. Pretty rare stuff!



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 Posted: Sun May 15th, 2016 04:30 am
   
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Salada
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Keith & Gang,

I did warn you - prepare to be bored !.

It is difficult to understand the Hazeltine remains from just a few photos so I have guessed some of the details. But first I should explain a few technical bits before looking at the Hazeltine remains because they are rather unusual.

Cornish pumps have a large vertical cylinder, the piston rod of which connects upwards to one end of a heavy rocking beam (a "Bob" in Cornish dialect). This bob is pivoted on the front wall (hence the "Bob Wall") of the engine house & the outboard end of the bob is attached to the top of the pump rod which extends down-shaft to the actual pumps *. The bob wall has to be solid & substantially built because it bears the weight of all the "pit-work" (Cornish for pump rod + pump plungers ) and the thrust of the steam cylinder & rocking beam.

So as the piston & piston rod move down in the steam cylinder the inboard end of the bob is also pulled down, pivoted on the bob wall, and the outboard end of the bob swings up, lifting up the pump rod with it. At the end of the piston downstroke the steam is cut off so the weight of the pump rod & pump plungers * descends back into the shaft,  rocking the bob the other way and returning the piston to the top of the cylinder for the next stroke - simultaneously displacing the water in the pump cylinders *. Cornish pumps pump only on the return stroke, when the pump rod moves back downwards under gravity.

Cornish Pump (or Cornish Beam Engine) steam cylinders have to be large because they work on low pressure steam so they are mounted at ground level inside the engine house. The motive power is not purely derived from steam pressure but mainly from atmospheric pressure as the steam condenses to form a vacuum under the piston.

Looking at the 2nd photo, Post No 873,  (after the Gilpin era B&W pic) I assume that the shaft was where the small conifer now grows & where bits of timber are falling into -- one of Keith's photos shows some neat dry stone walling with an arched head set into the (assumed) bob wall but I don't think that is the shaft collar - no-one would build a bob wall directly over the edge of the collar.

I think what Keith has photographed is a "Bob", but a different kind of bob (Cornish can be confusing to furriners !) - of which there are 2 types.

A "Balance Bob" was sometimes used to assist the steam cylinder by acting as a counter weight to the weight of the pit-work. This type of bob was also pivoted - one end was attached to the top end of the pump rod, the other end was fixed to a timber box or frame filled with heavy rocks. As the pit-work descended the counter weight was raised so that it helped to lift up the pit-work at the start of the next stroke. Usually used on deep shafts to help overcome the weight of all the pump rodding or possibly where the steam cylinder was undersized for the duty involved.

An "Angle Bob" was used to change the direction of pull of the engine rocking beam (or bob !). Typically used down-shaft where the shaft changed direction (not all shafts are straight vertical !) or could be used at surface as an early-day "power take-off" to drive some other machinery besides the pump.

I'm 90% + sure that Keith's photos show this second type of bob, not a rocking beam bob,  so it is either a balance bob or an angle bob. The arm descending into the arch-headed stone walling could be attached to a counter weight in a blind pit, the other arm attached to the head of the pump rod in the shaft proper. An unusual arrangement because the counter weight is more usually arranged at 90 deg to the overhead rocking beam beyond the bob wall (but it doesn't have to be).

So far, so good. this could definitely be a Cornish pump with ancillary balance bob.

But, But .......

The assumed bob wall doesn't look anything like a bob wall; it doesn't look sufficiently substantial. The neat edge of the left hand side wall of the "engine house" suggests that maybe there was a large opening facing onto the shaft, above the assumed balance bob remains. Or, possibly, the walls weren't tied into each other at the corner & the bob wall has simply fallen in or been robbed for stone ?  Who knows ??   

There was a large Cornish contingent at Caribou mine camp in the adjacent County so Cornish technology wasn't too far away. I don't know the extent of Cornish involvement in Gilpin County but I guess, on balance (bob)(!) this IS some version of a Cornish pump, - maybe.

The origin of "Cousin Jack" is uncertain but is generally taken to be similar to Keith's explanation : "Have you got a job for my cousin Jack ?" or  "My cousin, Jack, is an experienced miner looking for employment". There are some other theories though.

Anyone still awake ???   zzzzzz....... I thought not. Roll on Keith's next installment !.

Regards,     Michael

* Because the Cornish beam engine is essentially an atmospheric engine there is a limit as to the height & weight of water it can lift. The max pressure on the steam piston is therefore a vacuum of approx 14 psi, give or take a bit of help from low pressure steam above the piston, which is why the steam cylinder bore is so large, typically 30" - 40" diameter, up to 80" +. (that's a big cylinder !).  The max vertical lift of water is around 30' ** from one stroke of the steam piston so 'repeater' plunger pumps are fastened to the main shaft pump rod every 30' or so that the column of mine drain water eventually reaches "grass" (ground level).

** atmospheric pressure x piston area/10 lbs - (weight per gall of mine drain water).
  
..zzzzzzzzzz...
  


Last edited on Sun May 15th, 2016 05:53 am by Salada

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 Posted: Sun May 15th, 2016 05:46 am
   
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Salada
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Thanks Duane.

Cornish pumps were used worldwide, wherever Cornish mine engineers & mine "Captains" (mine bosses) were involved - Spain, Mexico, Australia, S America etc. & certainly N America also but I'm not sure of the extent of Cornish technology in the U.S. West & Southwest (I think maybe there were some on the early Comstock, NV ?). There are some remains of a Cornish engine house way south of Palm Springs CA in the southern Mojave but no engine or pumps. The strong 'bob wall' design with the high up opening for the main bob beam is definitive.

We (Madame Salada & myself) were surprised & disappointed how little remains of even really remote SW U.S. mining sites; people seem to have driven miles to demolish/steal/remove stuff - or cover with graffiti.  Even stone buildings were demolished but then the remains just left there. Why ? Strange !. Maybe your EPA* people ?  We still have several Cornish beam engines in steam as visitor attractions.

The Cornish pump design was very simple but quite clever - it could raise enormous volumes of water fairly efficiently from a simple low pressure boiler & also cope with stones, gravel & acid water - no problem. But it needed lots of heavy construction - a well built engine house & heavy pit-work with intermediate down shaft rollers to guide the heavy pump rods - no match for the newer electric 'down-hole' pumps, provided you had a heavy duty genny/alternator.

* your EPA seem to have a serious hangup with arsenic residues. We have some of the world's largest pure arsenic mines with tailings ponds & dumps still full of the stuff. No-one has ever died & there ain't no heaps of dead wildlife - kids cycle through it, hikers walk through it.  Just don't eat the stuff or drink it - simples !. Looking at it or breathing it in don't kill you. Only an idiot could manage to voluntarily die of arsenic poisoning. 

Regards,               Michael

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 Posted: Sun May 15th, 2016 07:54 pm
   
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Herb Kephart
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Salada

So where does ''And Bobs your uncle'' fit into all this pump technology?

Herb



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 Posted: Sun May 15th, 2016 08:09 pm
   
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W C Greene
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Michael, you got it! Here in the US, there are many numb-nuts or as Bugs Bunny calls em'..."ultra maroons"...and it seems that most of them get jobs at the EPA. And those who don't qualify for the EPA get to work at the IRS!

my name has been changed to protect the guilty

####NOW, BACK TO THE GILPIN TRAM######



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 Posted: Tue May 17th, 2016 12:33 am
   
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Salada
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Depends which Bob you mean Herb :

Two Bob (2 shillings in £ Sterling before they shrunk the value of our money by metrification).

Or a Bobby (old term for a foot patrol policeman before they all rode around in cars).

And as it happens, Bob was my uncle !

Now, in the words of the guilty, a.k.a. Mr Greene, - back to the Gilpin.

Regards,      Michael

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 Posted: Wed May 18th, 2016 09:59 am
   
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NevadaBlue
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hmmm... we must be related because Bob was my Uncle too!



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 Posted: Wed May 18th, 2016 08:12 pm
   
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Herb Kephart
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I meant the one at the end of a explanation of how to do something--IE----------- place the plug into the hole and Bob's yer Uncle.

Or do you Brits only have to explain things to us?

Bert---who incidentally is no one's Uncle (or Aunt, either)



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 Posted: Fri May 20th, 2016 03:50 am
   
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Salada
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Herb Kephart wrote: I meant the one at the end of a explanation of how to do something--IE----------- place the plug into the hole and Bob's yer Uncle.

Or do you Brits only have to explain things to us?

Bert---who incidentally is no one's Uncle (or Aunt, either)

"Bob's your uncle"  -  It simply means that once you have been told how to do 'X' task, the completion of 'X' is so simple/easy that only a fool could fail to succeed.

Regards,             Michael

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 Posted: Fri May 20th, 2016 07:49 pm
   
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Herb Kephart
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Kinda unfair to all the Bobs of the world----

The Grannys, at least got a mouthful of snot, from ''sucking eggs''

Herbert----and yes, you can tell everybody what a Herbert is England----



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