Improvements in or relating to Automatic Safety Devices for Lifts, . Hoists, and the like.
Year: 1897

page_text: Date of Application, 15th June, 1897-Accepted, 21st Aug.,
1897
Improvements in or relating to Automatic Safety Devices for Lifts, .
Hoists, and the like.
A communication from ANTOINE MUSNICKI, of Brussels, in the Kingdom of Belgium,
Engineer.
I, ALFRED JULIUS BOULT, of 111 Hatton Garden, 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:―.
The automatic safety device according to the present invention is illustrated in
Figs. 1 to 5 of the accompanying drawing, as applied to a pit-cage, in two forms of
construction. The object of this device is to cut the cable whether of hemp or the
like or of round or flat metal, as usually employed, at the moment when the cage
during its ascent passes beyond the proper limit of its ascent. If the cage continued
to be raised, the cage would strike with its top against the framing constituting the
entrance of the pit a very serious accident would occur. As such accidents are of
frequent occurrence owing to want of attention on the part of the engineer or to some
circumstance over which he has no control preventing him from stopping the engine
in time, the safety device according to present invention has been devised.
The safety device shown in Figs. 1 to 3 is chiefly destined for cutting hemp and
like cables and that in Figs. 4 and 5 for metal cables. Fig. 3 is a diagrammatic view
showing the relative positions of the knives on an enlarged scale. The safety device
according to the present invention is constituted by two knives A A¹ in the shape of
a fork (see Fig. 2) secured in holders B B which are pivotted about pins C C
secured on a cross bar of the framing. These knife-holders B B' have arins D D¹
pivotted at E E¹ to rods F F1; the latter being hinged at their other ends at G G¹,
to double armed levers H K H₁ K¹ pivotted on pins J J¹ which are secured to the
framing. When the cage in its ascent rises beyond the points K, the projecting
parts as L. L' strike against the arms K K¹ whereby the arm of the levers H H
violently draw down the rod, F F which thus causes by means of the lever arms D D¹
the knife holders B B to advance towards the cables so that the knives A A¹ penetrate
into the cable and completely sever it. When the cable is thus cut, the cage falls
back on its safety catches and remains stationary, whilst the cut part of the cable
continues to rise alone, so that an accident which might have happened if the cage
were raised beyond the prescribed limit is thereby prevented.
The shape of the knives A A' (Fig. 2) is important as it ensures the effective
cutting of the material of the cable by the knives. Each knife is preferably secured
by bolts to its holder and has the shape of a fine blade which is arranged a little
behind the edge of the holder, which is preferably bifurcated. Owing to this
construction the cable is first surrounded by the two branches of the bifurcated
knife-holders B B¹ and is then cut by the blade of the knives A. A¹.
The device when applied to round or flat metal cables (Figs. 4 and 5) consists of
two eccentric discs c c¹ pivotted on pins g g' hinged by means of arms h h¹ at i i
to the rods k k¹. The latter have the same function as the rods F F¹ of Fig. 1.

page_text: The two discs c c' have recessed parts opposite each other without teeth and of such
shape as to normally enable the cable m to pass between them. Whilst in the case
of an accident it is caught between the lower parts f f¹ provided with serrations or
saw-teeth. The discs c c are provided on their meeting faces with toothed
portions d d d d' which engage with each other so as to ensure simultaneous
inovement of the two discs. One, say the left-hand disc c carries a knife a
with a cutting edge secured say by bolts bb, so that when the disc is rotated upwardly
secured by bolts bb, so that when the disc is rotated upwardly the.knife cuts into the
cable m, severing it completely and is applied' with its upper projecting face against
the recessed lower face of the right hand disc c¹. This modification operates in
principle in exactly the same manner as the first construction the only characteristic
difference necessitated by a harder material to be cut being that here the pull of
the cable m itself produces the force necessary to make the cutting edge of the knife a
penetrate into the cable and to sever it, when the cable. becomes caught between the
teeth of the lower part ff' of the eccentric disc c c¹, as the cable draws these parts
upwards.
Having now particularly described and ascertained the nature of the said
Invention 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 :-
1. A safety device for lifts, hoists and the like characterised by the arrangement
of two knives carried on bifurcated knife-holders connected by a series of levers
operated by the top of the cage striking against projecting tappets or fingers when
the cage passes beyond its prescribed limit, substantially as described.
2. A safety device for lifts, hoists and the like comprising two eccentric discs with.
engaging toothed edges and having recessed portions to normally allow free passage
of the cable and with serrated portions to engage said cable when the discs are
moved partly rotated by lever connections of the character described, whereby the
traction of the cable itself causes the cutting edge of a knife secured to one of the
discs to sever the cable completely and to press against the corresponding face of the
opposite disc, substantially as described.
3. The combination and arrangement of parts constituting the complete safety
device for lifts, hoists and the like, substantially as described and illustrated in
Figs. 1, 2 and 3 or in Figs. 3 and 4 of the accompanying drawings.
Dated this 15th day of June 1897.
BOULT & WADE,
Agents for the Applicant.