IM- PROVEMENTS IN SAFETY CAGES FOR MINES, AND IN MEANS OR APPARATUS FOR PREVENTING OVERWINDING OF THE SAME
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Martin Thomson at the Office of the
Commissioners of Patents on the 28th September 1877.
"
MARTIN THOMSON, of Rosehall, in the County of Lanark, North Britain. IM-
PROVEMENTS IN SAFETY CAGES FOR MINES, AND IN MEANS OR APPARATUS FOR
PREVENTING OVERWINDING OF THE SAME
This Invention relates to improvements in safety cages for the prevention of
accidents at mine shafts, either by overwinding or the breaking of the ropes or
chains, which are of frequent occurrence.
The general framing and mode of hanging, and hoisting, and lowering the cage
may be similar to that in general use, but the nature of the present Invention con-
sists in fitting hinged flaps or lugs at or near the corners of the cage, preferably near
its upper end. These flaps hang or are kept flush with the sides of the cage by
cords or chains attached to their lower closing lip or inner face, and led round
rollers or pulleys inside the cage frame, and thence up and connected by a ring or
otherwise to the main hoisting or carrying rope or chain of the cage, these closing
ropes or chains being of the exact length required to keep the flaps close without
assisting in supporting the cage. Another cord or chain is attached to the outer
side or face of each flap, and is led up over a pulley or roller in the framing of the
cage, and to the free end of this cord is hung a weight, which, whenever the inside
closing cord is slackened by the breaking of the main hoisting rope, at once counter-
balances and opens the flap to the horizontal position at which it is held by a knee
or feather on it abutting against the cage frame. The two sides of the main shaft
are fitted with cross beams or buntings at intervals of a few feet apart all the way
from the bottom up to near the level of the ordinary winding apparatus at the pit
mouth, so that when the main rope breaks, the before-mentioned flaps fly open by
gripping or resting on one or other of the set of the cross beams or buntings, and
so arrest the descent of the cage within a few feet at most from the position where
the break takes place.
To soften the dead weight of the cage in falling on to the beams or "buntings,"
blade springs are fitted at their upper ends to the side of the framing of the cage,
and which are opened out by the before-mentioned flaps, as these are opened, so as

page_text: to bear against the sides of the central guide rails, and prevent shocks or damage
to the cage.
Another improvement consists in hanging the cage to the lower loop of an $
shaped link, known as the "safety dog," swivelling on a pin at its centre, passed
through a bar or shackle, to the upper end of which the hoisting rope is secured.
The shackle has an oscillating cross arm or lever fulcrumed above the level of the
S link, and with a spring under its longer arm to keep it in a nearly horizontal
position; the other arm having a slot in it, which takes on to a horn or projection
on the upper end of the S link when the cross arm is in its normal position, so that
when by any accident or oversight the cage is hoisted too high, the long free end of
the cross oscillating arm comes up against a beam or other equivalent at the pit
head, and so releases the horn on the S link from the slot in the other arm, and the
link being relieved cants over and allows the ring or chain of the cage to slip out
of the lower end of the S link, thus immediately releasing the cage, which is then
caught by the flaps and buntings as already explained, thus effectually preventing
accidents by overwinding.