CERTAIN IMPROVEMENTS IN APPARATUS TO BE USED WITH CAGES FOR MINES AND SHAFTS FOR THE PREVENTION OF ACCIDENTS THROUGH OVERWINDING OR BREAKAGE OF THE WINDING ROPE
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by William Scott Underhill and
Frederick John Snow at the Office of the Commissioners of Patents,
with their Petition, on the 24th April 1873.
We, WILLIAM SCOTT UNDERHILL, of Newport, in the County of Salop,
Manufacturer, and FREDERICK JOHN SNOw, of Shiffnal, in the same
County, Engineer, do hereby declare the nature of the said Invention
for "CERTAIN IMPROVEMENTS IN APPARATUS TO BE USED WITH CAGES FOR MINES
AND SHAFTS FOR THE PREVENTION OF ACCIDENTS THROUGH OVERWINDING OR
BREAKAGE OF THE WINDING ROPE," to be as follows:
Our Invention consists of the arrangement of certain levers, catches,
and springs, as hereinafter described, the liberation and action of which
in the event of overwinding takes place entirely at the outside of the
cage, whereby we dispense with the central ring or eye hitherto fixed for
the purpose to the pit frame, immediately below the rope, pulley, or
whimsey wheel, and thus the violent concussion which now takes place
when upon the occasion of overwinding the cage comes against the usual
fixed cross beam is avoided..

page_text: Our Invention relates more particularly to the prevention of accidents
from overwinding, although it is also adapted to prevent accidents from
the breakage of the winding rope or chain.
In carrying out our said Invention we attach two ordinary diagonal
suspension chains to the winding rope or chain, and from these we
suspend the cage. The supporting catches to which the said diagonal
chains are attached, are not permanently secured to the cage or other
receptacle employed, but are held vertically in position at each side of
the cage by means of latches turning upon horizontal pins, each latch
having a handle or tail end projecting horizontally when in ordinary use. 1
The guides between which the cage travels terminate at a suitable height
above the mouth of the pit, and are furnished with strong bolts which
project in such manner as to catch and depress the tail ends or handles
of the aforesaid latches should the said cage be over wound or raised too
high. The catches are thereby set free from the cage, and pass away 1
with the winding rope.
In departing each catch lifts into a horizontal position an arm which
is hinged at its upper end to the said cage, and which, when it is in its
ordinary vertical position transmits the weight of the cage to the sup-
porting catch. Each hinged arm has a stop to prevent it from rising :
above the horizontal line. Upon the said cage attempting to fall after
the release of the supporting catches, and consequently of the winding
rope or chain, the said horizontal hinged arms catch upon the top of the
said vertical guides and and support the cage in safety.
In order to prevent undue concussion we place an elastic buffer upon
the top of each guide bar to receive each of the aforesaid horizontal
arms.
We also provide elastic buffers upon the platform of the cage so that
should its upward velocity at the time of overwinding be very great the
said elastic buffers will come into contact with the projecting bolts upon
the vertical guides, and will without undue concussion prevent the cage
from rising entirely clear of the vertical guides.
We make the aforesaid projecting bolts moveable horizontally, so that
they may be held out of the way when the cage is being placed in
position between the guides, or when it is desired to lift the cage entirely

page_text: In adapting our Invention to prevent accidents from the breakage of
the winding rope, we make each of the aforesaid supporting catches in
two pieces, the upper piece being hinged to the lower piece. The upper
piece has an external hook or catch at its upper end, which when the
rope breaks is forced by a spring into gear with ratchet shaped teeth
formed upon the inner face of each guide bar; but as long as the rope or
chain is unbroken and the cage hangs therefrom the tension of the
diagonal suspension chains counteracts the force of the spring and holds
the upper catches out of action.
The apparatus herein described is intended to be employed in con-
nexion with cages or other receptacles in mining shafts or other lifts or
hoists, and where two guide bars are used, but as will be evident a
trifling modification will enable the same apparatus to be used where.
there are more than two guide bars, as is sometimes the case.