IMPROVEMENTS IN SAFETY APPARATUS FOR LIFTS OR HOISTS."
Year: 1876

page_text: LETTERS PATENT to John Dence, of 28, Mark Lane, in the City of London;
Civil Engineer, for the Invention of "IMPROVEMENTS IN SAFETY APPARATUS
FOR LIFTS OR HOISTS."
PROVISIONAL SPECIFICATION left by the said John Dence at the Office of
the Commissioners of Patents on the 16th February 1876.
(*
JOHN DENCE, of 28, Mark Lane, in the City of London, Civil Engineer. IM-
PROVEMENTS IN SAFETY APPARATUS FOR LIFTS OR HOISTS.".
This Invention relates to improvements in safety apparatus for lift cages or boxes
applicable to lifts for warehouses, collierys, and other like purposes, working in
guides either of wood or iron, whereby the cage will be instantly suspended if the
lifting chain or rope breaks. For this purpose safety levers are arranged with
suitable jaws securely attached to a cross shaft or otherwise mounted upon the cage
or box, the centre bearings or fulcrum being placed at a convenient distance from
the centre of gravity of the cage. This bearing is attached to the framework of the
cage, and upon the cross shaft (or otherwise connected with the safety levers) other
lever or levers are attached, which are connected to the lifting chain by another
chain or otherwise, the object of which is to keep the levers level or horizontal, in
order that so long as the lifting rope or chain is intact the jaws will run free on the
guides, but so soon as the lifting rope or chain breaks a spring is provided that acts
instantly on the second chain or connecting chain and levers, by means of which the
jaws at once close upon the guides, and the cage or box is instantly brought to a
stand at whatever height it may be.
In cases where a balance weight is required to be used a similar arrangement
may be adopted in connection with it to prevent it also from falling when danger is
apprehended.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Dence in the Great Seal Patent Office on the 15th August
1876.
JOHN DENCE, of 28, Mark Lane, in the City of London, Civil Engineer.
PROVEMENTS IN SAFETY APPARATUS FOR LIFTS OR HOISTS."
"IM-
This Invention relates to improvements in safety apparatus for lift cages or boxes
applicable to lifts for warehouses, collieries, and other like purposes, working in
guides either of wood or iron, whereby the cage will be instantly suspended if the
lifting chain or rope breaks." For this purpose safety levers are arranged with
suitable jaws securely attached to a cross shaft or otherwise mounted upon the cage
or box, the centre bearings or fulcrum being placed at a convenient distance from
the centre of gravity of the cage. This bearing is attached to the framework of the
cage, and upon the cross shaft (or otherwise connected with the safety levers)
another lever or levers are attached, which are connected to the lifting chain by
another chain or otherwise, the object of which is to keep the levers level or
horizontal, in order that so long as the lifting rope or chain is intact the jaws will
run free on the guides, but so soon as the lifting rope or chain breaks a spring is
provided that acts instantly on the second chain or connecting chain and levers, by
means of which the jaws at once close upon the guides, and the cage or box is
instantly brought to a stand, at whatever height it may be.
In cases where a balance weight is required to be used a similar arrangement may
be adopted in connection with it to prevent it also from falling where danger is
apprehended.
And in order that my improvements may be clearly understood and readily
carried into practice I will proceed to describe the same more fully, reference being
made to the Drawings hereunto annexed.
My improvements may be applied to the ordinary hand or steam colliery or other
lifts, but I will describe my improvements as applied to a hand-power lift, as shewn
in the accompanying Drawings, which is constructed in the ordinary way, with the
exception that the side top bars a, a, for suspending the cage are made with bosses b
forged upon them to receive the strong cross shaft c or links for same. On each
end of this cross shaft I place (and securely attach) a strong arm or lever d provided
with jaws for clutching the vertical wooden guides m when the chain breaks, and
in the centre or thereabouts of the cross shaft c I place a short bent leverk, to the ond
of which is attached a spiral or other spring for bringing the levers in contact with
the vertical wood guides m A small chain e is also attached to the same end of
this lever and to the ring f. The use of this chain is merely to keep the levers & in
a horizontal position whilst the cage is working correctly, and the rope or chain
remains unbroken.
The portion of chain from the ring f to the shackle on cross bar g is made much
stronger than is requisite to lift the load, so that in any case the fracture must occur
in the chain or rope between the ring fand the balance weight h.
The action of the apparatus is as follows:-Supposing the lifting chain & breaks,
the spiral or other spring j, always being in tension would come into action, and
cause the levers d.to come in contact with the vertical guides, and in the position as
shewn by the dotted lines (sufficient play between the guides and the vertical
guides m being allowed); this being the case the weight of the cage would be
transferred from the centre or suspending shackle to the shaft c, and would cause
the levers d to bite upon the vertical guides m, and thus bring the cage to rest.
same apparatus may be applied to the balance weight, although the ordinary
shooting bars (known as the spread eagle safety gear) are shewn on the Drawing.
Having thus described the nature of my improvements, and the manner of per-
forming or carrying the same into practice, what I claim is, the improved arrange-
ment and combination of safety apparatus for arresting the descent of the suspended
The

page_text: cage, box, or weight of colliery, warehouse, or other lifts, substantially as herein
described and represented in the Drawings hereunto annexed.
In witness whereof, I, the said John Dence, have hereunto set my hand and
seal, this Fifteenth day of August, in the year of our Lord One thousand
eight hundred and seventy-six.
Witness,
J.. G. TONGUE,
Patent Agent,
34, Southampton Buildings,
W.C.
JOHN DENCE. (L.S.)