Improvements in Safety Apparatus for Lifts, Hoists, and the like.
Year: 1893

page_text: Date of Application, 14th Apr., 1893
Complete Specification Left, 1st Feb., 1894-Accepted, 14th Apr., 1894
PROVISIONAL SPECIFICATION.
Improvements in Safety Apparatus for Lifts, Hoists, and the like.
A communication from CHARLES THOMAS, of 9, Rue des Bornes, Tirlemont, in
the Kingdom of Belgium, Mechanical Engineer.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:-
:-
This apparatus comprises two grooved guides secured to the cage and two tapered
toothed jaws which move in these grooves and which are operated on by levers and
springs.
A set of these devices may be provided at each side of the cage. Whatever
their arrangement which varies according to the construction of the cage, their
mode of operation is always the same.
The levers which communicate with the safety apparatus of the cage by means
of rods or equivalent, cause the toothed cones to move automatically. When the
rope or cable is stretched i.e. when the cage is suspended the levers retain the cones
in their lowered position where they are out of contact with the rail. If the rope
or cable breaks the levers being no longer suspended fall and this movement
accelerated by springs, raises the cones which gradually tighten and grip the guide
rails so as to almost instantaneously stop the whole apparatus without causing it to
sustain any shock.
This exceedingly simple apparatus may be applied to cages made of wood or
iron and may be modified without departure from the spirit of the invention.
Dated this 14th dow of Anvil 1802
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Safety Apparatus for Lifts, Hoists, and the like.
A communication from CHARLES THOMAS, of 9, Rue des Bornes, Tirlemont, in
the Kingdom of Belgium, Mechanical Engineer.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This apparatus comprises two grooved guide-pieces A which are secured to a
cross-beam, and in which are adapted to slide two wedge-shaped toothed jaws or
clutches B, connected link wise at their lower ends C with double levers D.
The arrangement of these parts is on the right and left of the guide-bar E.
Figure 1 shows the levers and guide-pieces;
Figure 2 the suspension device for the cage; and
Figure 3 a horizontal cross-section of the guide-bar, jaws and guide pieces,
the jaws in this figure gripping the guide bar.

page_text: :-
The mode of operation of this stop-clutch or gripper device is as follows:-
So long as the rope or lift-chain, by which the cage is hoisted and lowered, is
kept taut by the weight of the cage, suspended from it by the ring F, the parts G H
and C K are drawn upwards and the wedge-shaped gripper-jaws B are held down
so that the guide-bar E, as shown in Fig. 1 is free of contact with them in their
vertical up and down passage. But should the rope break, at that moment all the
parts GHC K and their connections, .e., levers, chains, and drawbars, drop by
their own weight, forcing the wedge-shaped jaws B upwards and into contact with
the guide-bar E so that as shown in Fig. 3 the serrated surfaces of the said
jaws grip the bar fast and arrest the downward drop of the cage, which is
consequently securely upheld.
The sudden pressure or grip of the serrated
jaws B upon the guide-bar E may be
materially strengthened by the reaction of springs such as L.
The device, as will be seen, is extremely simple and its safe and reliable operation
depends essentially upon the firm abutment which the wedge-shaped, serrated
jaws B find in, and the support they obtain from, the fixed cross-beam or guide-
piece A as well as from the vertical guide-bar E, by reason of the wedge-action
of the gripper jaws, which has always been found the best mechanical arrangement
for such a purpose.
This stop-clutch, or safety gripper, can also be applied in various other forms
to all kinds of cages, lifts, elevators, etc., and the principle of the invention
remains unaffected if the modification be adopted of using four sets of such wedge-
shaped serrated jaws one at each of the four corners of the cage, instead of in the
middle only.
In case they are employed at each side or corner, of course it will be necessary
to provide four guide-bars.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent, and in what manner
the same is to be performed, I declare that what I claim is ;-
A safety clutch or jaw-gripping device to catch and hold fast the cage in the
event of the lift-rope breaking characterised by the arrangement of jaw-grippers B
which are made to slide in two guide-pieces A inclined towards the axis of the
guide-bar E in such manner that the pressure of the serrated surfaces of these
jaw-grippers against the guide-bar is brought about by wedge-action so soon as the
rope breaks when the lower ends C of the jaw-grippers by reason of the weight of
levers rods and chains and connections with them acting by pivot joints are pressed
upwards while at the same time the pressure of the jaw-grippers on the guide-bar E
is materially strengthened by the reaction of suitable springs L substantially as
described and illustrated in the accompanying drawings.
Dated this 1st day of February 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicant.