More mining than caving

Brains

Brains

Well-known member
13411682_10154128519756422_9112405025833815662_o.jpg


So who knows what this is? No cheating by following the image back to its location!
 
Roger W

Roger W

Well-known member
Is it some sort of fuse by any chance?  Adjust the time delay by how far the inner part is pushed into the outer one, then set things off by a good jerk on the wire from a safe distance down the tunnel?
 
Brains

Brains

Well-known member
Tell_Tale_preview.jpg


We have a winner!  It is a roof tell tale to show if it is delaminating. A long hole is drilled in the roof and the small inner rod was fixed to the end by the wire and one of the clips top right. The outer tube is fixed near the roof by the other clip with the two overlapping, both showing green. If the roof starts to come away between the two fixings the inner rod will move to yellow then red, indicating failure. If the roof delaminates below the bottom fixing the outer tube will go yellow then red. Lines provided for finer measurement. This one is from the Wilts freestone quarries, but also used extensivelly in coal mines. Not sure if used in hard rock mines but probably.
Well done  ;)
 
royfellows

royfellows

Well-known member
That one beat me, and I'm supposed to be a mining man. Ouch

Anyway, try this, its useful to know as well.

Two rods held together by an elastic band, so that they will extend horizontally.
Obviously a measuring device of some sort but for what? Why not use an extending steel rule.
 
Brains

Brains

Well-known member
royfellows said:
YOU! I might have known
:LOL:
Click to expand...

Had a part time job in the wood working industry, using sticks givea an accurate length, tapes and string are fallible...
 
ChrisJC

ChrisJC

Well-known member
It is called a Telltale. You find them all over the roof in unstable mines. Boulby Potash must use millions.

Chris.
 
T

tamarmole

Active member
Brains said:
Measuring sticks for cutting timber to length, better than a tape measure any day
Click to expand...

One of the major advantages of a timberman's measure is that you are able to test whether the length of cut timber can be manoeuvred into place without catching on obstructions etc.
 
J

Judi Durber

Member
A long hole is drilled in the roof and the small inner rod was fixed to the end by the wire and one of the clips top right. The outer tube is fixed near the roof by the other clip with the two overlapping, both showing green. If the roof starts to come away between the two fixings the inner rod will move to yellow then red, indicating failure. If the roof delaminates below the bottom fixing the outer tube will go yellow then red
Click to expand...

Can't follow the explanation at all.  :mad:  :-[  Can we have a before and after pic please  :) Really interesting though
 
Brains

Brains

Well-known member
In use in good ground it should appear similar to the photo, with both green sectors showing. The roof line would be around the upper green band. If the roof starts to delaminate anywhere between the roof and top end of the fixing drill hole (10 or 20m) one or other of the coloured parts will appear to be drawn into the roof and so change colour through yellow to red. Where the roof is failing will effect one or the other part, the inner being the section from about +1m to the end of the hole (+10 or 20m), and the outer showing the movement from the roof line to +1m. Hopefully with the diagram this will help explain how they work?
 
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