IM- PROVEMENTS IN PLATFORM LIFTS OR HOISTS
Year: 1872

page_text: LETTERS PATENT to Robert William Eddison, of the Steam Plough
Works, Leeds, in the County of York, for the Invention of "IM-
PROVEMENTS IN PLATFORM LIFTS OR HOISTS."-A communication from
abroad by Benjamin Tatham, of New York, and John W. Brittin,
of Brooklyn. both in the United States of America.
PROVISIONAL SPECIFICATION left by the said Robert William Eddison
at the Office of the Commissioners of Patents, with his Petition,
on the 20th July 1872.
I, ROBERT WILLIAM EDDISON, of the Steam Plough Works, Leeds,
5 in the County of York, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN PLATFORM LIFTS OR HOISTS," to be as
follows:-
This Invention consists in combining with the cage or platform of
platform lifts or hoists a mechanical automatic governor to arrest the
> descent of the cage or platform should it descend too rapidly,. such
automatic governor receiving, by contact with the stationary framework,
a positive motion necessary to the descent of the platform, but which is

page_text: automatically stopped when the descent of the platform exceeds a given
velocity.
The following is the manner in which it is preferred to carry out the
Invention: On the sides of the stationary frame or shaft are arranged
zig-zag channels, and within these channels the ends of a strong round
bar, suspended below the platform and extending across its centre; freely
travel. On this bar are mounted blocks, upon the upper surface of
which are one or more teeth. Within these blocks the bar will freely
revolve. To the under side of the platform are secured two rack bars one
above each of the blocks. As the platform descends with ordinary
velocity the bar and its blocks will describe a constant reciprocating
motion upon the zig-zag guide corresponding with the shape of the
channels, and preserving their relative distance below the platform so
that the teeth of the blocks will clear the rack bars, but upon the
breaking of the rope or other parts of the apparatus by which the
platform would be free to descend too rapidly, the bar having a
greater distance to travel, and being impeded in its course, will be
overtaken by the platform, and as soon as the teeth of the blocks
are received in the racks, all further motion will be instantly arrested.
The bar with its automatic stop may, if desired, be connected with
the upper part of the platform, so that in case of accident the platform
will be suspended therefrom, or the governor may be made by a frame
suspended below or above the platform and furnished with sliding bolts
working upon a system of cams on the stationary frame, or racks may
be formed on said frame having pinion wheels upon one or more bars
working in the racks as the platform descends, and so arranged, that by
the fall or too rapid descent of the platform the motion of these bolts or
pinion wheels or their equivalent will be automatically stopped, and
thereby prevent the further descent of the platform.
Other arrangements may be adopted for causing the descent of a cage
or platform to be arrested should it exceed a given velocity, by means of
a travelling governor which receives from the stationary framework a
positive motion necessary to the descent of the platform, and which
motion is automatically stopped whenever the platform descends too
quickly.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert William Eddison in the Great Seal Patent
Office on the 18th January 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
WILLIAM EDDISON, of the Steam Plough Works, Leeds, in the County
of York, send greeting.
my
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twentieth day of July, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give.
and grant unto me, the said Robert William Eddison, Her special license
that I, the said Robert William Eddison, my executors, administrators,
and assigns, or such others as I, the said Robert William Eddison,
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
PLATFORM LIFTS OR HOISTS," a communication to me from abroad by
Benjamin Tatham, of New York, and John W. Brittin, of Brooklyn,
both in the United States of America, upon the condition (amongst
others) that I, the said Robert William Eddison, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Robert William Eddison, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :-
This Invention consists in combining with the cage or platform of
platform lifts or hoists a mechanical automatic governor to arrest the
descent of the cage or platform should it descend too rapidly, such
automatic governor receiving by contact with the stationary framework

page_text: a positive to-and-fro motion necessary to the descent of the platform, and
having therefore to travel a greater distance than the platform itself, so
that should the platform be descending quicker than the automatic
governor the platform overtakes the governor and stops its movement,
thereby arresting the descent of the platform. This may be effected in
various ways.
One arrangement by which it can be effected is shewn at Figures 1, 2,
and 3 of the Drawings hereunto annexed. Figure 1 is a sectional front
view, Figure 2 a transverse vertical section, and Figure 3 a detached
sectional view of the lift or hoist. In these Figures letter A, Figure 1,
represents the platform, which is moved up and down between the
stationary frame B, B, by the rope C. On the sides of the stationary
frame are zig-zag channels a, a, and within these channels the ends of
the governor, a strong round bar b, suspended upon guides d at a short
distance below the platform and extending across its centre, freely
travel. On this bar are mounted blocks c, upon the upper surface of
which are formed one or more teeth e, as seen in Figures 2 and 3.
Within these blocks the bar will freely revolve. To the under side of the
platform are secured two rack bars f, f, one above each of the blocks c.
The racks correspond with the teeth of the blocks, and with them operate
as a self-acting stop to the motion of the bar 6. As the platform
descends with ordinary velocity the bar and its blocks will describe a
constant reciprocating motion upon the guide d, corresponding with the
shape of the channels and preserving their relative distance below the
platform, so that the teeth of the blocks c will clear the rack bars f, but
upon the breaking of the rope or other parts of the apparatus by which
the platform would be free to descend too rapidly, the bar 6 having a
greater distance to travel and being impeded in its course will be over-
taken by the platform, and as soon as the teeth of the blocks are received
in the racks all further motion will be instantly arrested.
A modification of the above arrangement is shewn at Figures 4 and 5.
In this modification the governor in place of being arranged to slide to
and fro on the guide d is carried by a swinging frame hung upon pins
at the upper part of the frame of the cage or platform. A represents
the platform or cage; B, the stationary frame; a, a, the zig-zag
channels; b, the governor bar on swinging frame d; c, blocks mounted
thercon, and having teeth e on their upper surface; f, f, are the rack
bars secured to the under side of the platform. In this case the rack

page_text: bars are curved to the arc of a circle, struck from the pins upon which
the frame d swings. In the arrangement shewn in the Drawing the
bar d is divided at the centre, and the two parts are there pivoted on
horizontal pins or axes, which allow the two parts to incline upwards if
the swinging frame is descending quicker than the blocks c. The bar
might however, if preferred, be in one piece, as in the arrangement
shewn at Figures 1, 2, and 3, and be capable of moving upwards in slots
in the swinging frame.
I would state that the Invention is not confined to the precise arrange-
ments of machinery shewn in the Drawings hereunto annexed, as other
arrangements of machinery for carrying out the Invention will readily
suggest themselves to any practical mechanic; as, for example, the bar
with its automatic stop may be connected with the upper part of the
platform, so that in case of accident the platform will be suspended
therefrom; or the governor may be made by a frame suspended below
or above the platform, and furnished with sliding bolts working upon a
system of cams on the stationary frames. In this case it is necessary to
provide the means of locking the bolts when they are projected (by
springs) into the recesses formed by the cams. This may be effected
variously. When the cams face toward the centre of the platform they
will give (to the bolts) a reciprocating motion (towards and, away from
the centre of platform) corresponding with their shape. If to the under
part of the platform we attach suitable wedges made to fit and occupy
the spaces which will be left vacant by the bolts when projected into the
recesses formed by the cams, it is evident that upon the fall upon the
suspended frame the wedges will lock the bolts outward, and thus arrest
all further descent; or racks may be formed on said frame having pinion
wheels upon one or more bars working in the racks as the platform
descends, and so arranged that by the fall or too rapid descent of the
platform the motion of these bolts or pinion wheels or their equivalent
will be automatically stopped, and thereby prevent the further descent-
of the platform.
Having thus described the nature of the Invention, and the manner of
performing the same, I would have it understood that what is claimed
is,-
The combination with the platform or one of platform lifte

page_text: work a positive to-and-fro motion, so that it shall descend in a zig-zag
course, and so have to travel through a greater distance than the platform
itself in order that if the platform is free to fall and descends quicker
than the governor bar or stop the movement of the stop and conse-
quently the descent of the platform shall be arrested.
The combined arrangement of the self-acting bar 6 and its automatic
stops e and f, or analogous device, to operate substantially as herein.
described.
In witness whereof, I, the said Robert William Eddison, have
hereunto set my hand and seal, this Twenty-sixth day of
December, in the year of our Lord One thousand eight hundred
and seventy-two.
K. W. EDDISON. (L.S.)