IMPROVED SAFETY APPARATUS FOR MINERS' CAGES, HOISTS, AND PIT WORKING
Year: 1876

page_text: LETTERS PATENT to Thomas Dobson, of 19, Salisbury Street, Strand, London,
and Kingston-upon-Hull, Gentleman, for the Invention of " IMPROVED
SAFETY APPARATUS FOR MINERS' CAGES, HOISTS, AND PIT WORKING."
Sealed the 9th September 1876, and dated the 16th March 1876.
PROVISIONAL SPECIFICATION left by the said Thomas Dobson at the Office
of the Commissioners of Patents on the 16th March 1876.
THOMAS DOBSON, of 19, Salisbury Street, Strand, London, and Kingston-upon-
Hull, Gentleman. "IMPROVED SAFETY APPARATUS FOR MINERS' CAGES, HOISTS,
AND PIT WORKING."
The mechanical apparatus forming the subject of this Invention is intended to
be applied to miners' cages, hoisting frames and such like apparatus, or to be
interposed between the lower end of the winding or hoisting rope or chain and
the cage, framework, or hoisting frame, and such safety apparatus is called into
action upon or by the breakage of the rope, chain, or its connections. It consists
in a metal framework and apparatus in which several lever arms, hinged at the
one end of each, and radiating from a common centre, are jointed at their inner
end to a central sliding piece or sleeve, which in turn is framed together and
supported by a metallic strap or sling which in turn is connected to the hoisting
rope or chain. The central sliding piece or sleeve is guided vertically on a vertical
pin or bar, having a spiral or other spring interposed between it and a cap or
button head securely attached to the head of the stud. At the outer extremity
of each radial arm is hinged a claw plate or other suitably shaped roughened
surface, for taking into, clipping, or gripping or expanding against the vertical
guides in the pit or lift when the strain due to the weight of the cage and its
contents becomes suddenly removed or disconnected from the supporting rope or
chain. Each of the radiating arms is hinged or jointed by a short connecting bar
or rod to a cross boss or reed sleeve, so that when the cage, box, framework, or
other form of apparatus or contrivance is freely suspended, the weight thereof acts
against the spring and holds it in compression, and contracts the radial lever arms
(through or by means of the pull on the short connecting bars or levers) into close
proximity, but upon the weight or load being disconnected or severed from the
supporting rope or chain, the arms are caused to expand uniformly and to come
in contact with and take their thrust against the vertical guides and so to arrest
[Price Gd.]

page_text: the further downward progress or motion of the cage or frame, box, or platform. The
central rod sliding through the upper sliding sleeve is at its lower end connected
to the cage, whilst the inner ends of the expanding arms are through or by means
of the loop or sling, connected with the rope or chain. Upon the rope or chain
breaking, the inner ends of the jointed radial arms or levers are by the joint action
of the spring and the freeing of the sliding sleeve and its attachment caused to
approach the lower cross boss, and so to throw out or expand the radial arms.
SPECIFICATION in pursuance of the conditions of. the Letters Patent filed by
the said Thomas Dobson in the Great Seal Patent Office on the 14th September
1876.
"
THOMAS DOBSON, of 19, Salisbury Street, Strand, London, and Kingston-upon-
Hull, Gentleman. IMPROVED SAFETY APPARATUS FOR MINERS' CAGES, HOISTS,
AND PIT WORKING."
The mechanical apparatus forming the subject of this Invention is intended to
be applied to miners' cages, hoisting frames, and such like apparatus, or to be
interposed between the lower end of the winding or hoisting rope or chain and
the cage, framework, or hoisting frame, and such safety apparatus is called into
action upon or by the breakage of the rope, chain, or its connections or otherwise
when so arranged. It consists in a metal framework and apparatus in which
several lever arms, hinged at the one end of each and radiating from a common
centre, are jointed at their inner end to a central sliding piece or sleeve which in
turn is framed together and supported by a metallic strap or sling, which in turn
is connected to the hoisting rope or chain. The central sliding piece or sleeve is
guided vertically on a vertical pin, rod, or bar, having a spiral or other spring
interposed between it and a cap or button head securely attached to the head of
the stud. At the outer extremity of each radial arm is hinged a claw plate or
other suitably shaped roughened surface for taking into, clipping, or gripping or
expanding against the vertical guides in the pit or lift when the strain due to the
weight of the cage and its contents becomes suddenly removed or disconnected
from the supporting rope or chain. Each of the radiating arms is hinged or jointed
by a short connecting bar or rod to a cross boss or freely moving sleeve, so that
when the cage, box, framework, or other form of apparatus or contrivance is freely
suspended, the weight thereof acts against the spring and holds it in compression
and contracts the radial lever arms (through or by means of the pull on their
short connecting bars or levers) into close proximity, but upon the weight or
load being disconnected or severed from the supporting rope or chain, or counter-
acted momentarily by pulling upon the longer end of a lever or spanner acting
upon the lower sleeve and so bringing the two sets of levers in closer proximity,
and so too causing the longer levers to expand and become extended and produce
the retarding effect, or hold the cage or hoist in suspension between the guides,
the arms are caused to expand uniformly and to come in contact with and take
their thrust against the vertical guides, and so to arrest the further downward
progress or motion of the cage or frame, box, or platform. The central rod sliding
through the upper sliding sleeve is at its lower end connected to the cage, whilst
the inner ends of the expanding arms are, through or by means of the loop or
sling, connected with the rope or chain. Upon the rope or chain breaking, the
inner ends of the jointed radial arms or levers are, by the joint action of the spring
and the freeing of the sliding sleeve and its attachment, caused to approach the
lower cross boss, and so to throw out or expand the radial arms and bring them
into action.
In the accompanying Sheet of Drawings, Figure 1 shows apparatus suitable for
application in a shaft where wooden guides are employed from top to bottom of

page_text: such shaft, and the apparatus is shown in the condition it would assume when
the upper end is attached to the pit rope, and the lower end is attached (by a
shackle) to the cage which is supposed to hang freely therefrom, and by its weight
to keep the spiral spring in compression, and so draw down and hold in close
proximity the longer arms having the hinged feet or claws on the lower (and outer)
ends thereof.
Figure 2 is a view of Figure 1 in a different position or that in which, by reason
of the breaking of the rope, the spring is supposed to be brought into play,
and the arms are expanded so as to come in contact with the guides, into which
the claws on the arms would take and retard the downward movement and suspend
the cage.
Figures 3, 4, and 5 are views of the apparatus applied to a warehouse hoist
worked by a double rope which passes over a sheave or pulley fitted in the inverted
sling, upon and in connection with a swivel sling, within which the vertical pin or
rod works vertically, and which is shown surrounded by the spiral spring in
Figs. 3 and 4 (although any other form of spring may be substituted for a spiral);
Figure 5 being a plan view of the upper side of the cage or box of warehouse
lift, with the apparatus fitted on the top thereof diagonally, so that by the ex-
pansion of the upper lever arms, which would take place by reason of the rope
breaking, or upon the rope being pulled within the cage or box and extending the
arms, would enable the person being lowered himself to check the movement of
the hoist, or to suspend its downward movement entirely without the breaking
of the suspending rope or other part of the suspending apparatus.
In Figures 1 and 2, A is the suspending rope or chain, having at its lower end
a thimble or eye connected with the upper end of the loop or sling C attached to
the cross head or cross links projecting from the sliding sleeve or socket G through
which the vertical pin or stud B passes, and between the upper side of which
socket or sleeve and the button head or nut upon its upper end, a spiral spring F
is shown (in Fig. 1 in a compressed condition, and in Fig. 2 in a free or extended
condition). The hinged upper arms H, H, are mounted at their inner ends within
the jaws projecting from the sliding sleeve or socket G, and at the outer ends
of those arms are the jointed claws or roughened foot pieces I, I, &c., which are
made to take into the guides; and there may be two or four thereof, and the
apparatus shown in Figs. 1 and 2 is intended to be fitted with four such arms
radiating from the centre of the apparatus and jointed on their inner ends to four
pairs of lugs forming joints upon the upper part of the upper sliding sleeve or
socket G. The lower cross like fitting K has four pairs of lugs L forming joints
similar to those in the upper sliding sleeve. To those are jointed the short radial
links M at the lower ends thereof, whilst the upper ends of such links are jointed
to the longer lever arms H, H. At the bottom of the vertical pin or stud, which
passes through the sleeve or socket G, and is surrounded by the spiral spring F,
the shackle or connection P from the cage or other suspended body is fitted through
the eye O at the bottom of such vertical pin through the said eye.
In Figures 3, 4, and 5 I have shown an adaptation of the apparatus illustrated
in Figures 1 and 2, and adapted specially from its shorter action for warehouse
hoists and such like purposes, the movement of the lever arms being very limited
and the clutch-like lever X being fitted to the top of the cage or box, and is
operated or called into action by means of the pull rope entering the cage and
accessible to the person within. In this application the lever arms are intended
to be fitted diagonally across the cage or box, and the roughened feet or claws
when expanded are made to come into contact with the upright guides fitted
diagonally in the well-hole within which the box or cage slides up and down.
Having now described my Invention, and illustrated some of its applications in
practice by a reference to Figures 1 and 2 (and by Figures 3, 4, and 5), I desire
it to be understood that I am aware that automatic clamps to bite upon the sides of
guides, and arrest the cage or box or other body when a rope or chain or some

page_text: part of the lifting device breaks are not broadly new, but what I claim as my
Invention is-
First. The combination with the use of vertical guides or guide ropes of two or
more radiating arms having upon their outer ends jointed roughened foot pieces
or clamps, or hinged clips (when used for ropes), and jointed to a vertically sliding
sleeve piece at their inner ends, and each of which radiating arms is connected at
some point between its inner and outer ends by means of a short link or bar
(hinged or jointed) at the lower end to a fixed central boss, and admitting of the
requisite change of position upon the spiral spring and other parts being brought
into play, all in the manner and for the purpose described.
Secondly. The combination of the lever arms to and with a fixed boss upon a
vertical spindle and a sliding sleeve or socket to which are attached (hinged or
jointed) the inner ends of the struts or expanding lever arms, as herein described in
the manner and for the purpose set forth.
Thirdly. The improved safety apparatus for miners' cages, hoists, and pit
workings as herein described, and as illustrated by the accompanying Sheet of
Drawings.
In witness whereof, I, the said Thomas Dobson, have hereunto set my hand
and seal, this Eighth day of September, in the year of our Lord Eighteen
hundred and seventy-six.
Witness,
GEORGE BOHN,
Civil Engr.,
Austrian Chambers,
Hull.
THOMAS DOBSON. (L.S.)