IMPROVEMENTS IN ELEVATORS
Year: 1878

page_text: LETTERS PATENT to Frederick Hart, of 59, Tavistock Road, Westbourne.
Park, W., Consulting Engineer, for the Invention of "IMPROVEMENTS IN
ELEVATORS."
Sealed the 13th June 1878, and dated the 5th January 1878.
PROVISIONAL SPECIFICATION left by the said Frederick Hart at the Office
of the Commissioners of Patents on the 5th January 1878.
FREDERICK HART, of 59, Tavistock Road, Westbourne Park, W., Consulting
Engineer. "IMPROVEMENTS IN ELEVATORS."
This Invention has for its object improvements in elevators, and relates especially
to that class of elevators in which a series of cages suitable for receiving passengers
or goods are kept in continuous motion ascending on one side and descending on
the other side. The cages are carried by an endless chain passing around chain
wheels at the top and bottom, and one of these chain wheels is driven by an engine
which is suitably controlled,
The cages stand in front of the chain, and are suspended by means of sling links
introduced into the chain at the places required. There is a sling link for each cage,
and the link carries a pin projecting out from it horizontally and at right angles to
the plane in which the chain travels. This pin enters an eye formed for it centrally
in the back of the cage at the upper part, and by it alone the cage hangs. Both in
ascending and in descending the cage is guided by rollers or small wheels running
on guides of angle iron. One pair of rollers carried by arms on the sling link
controls the tendency of the upper part of the cage to fall forward, and at the same
time steadies the cage laterally.
Another pair of rollers upon an axis fixed to the lower part of the cage and
running upon other angle iron guides (set in front of the first pair of guides)
prevents the lower part of the cage tipping towards the back, which if free, it would
D

page_text: do in consequence of the point of suspension being in rear of the centre of gravity
of the cage, thus the guiding of the cage is effectually provided for so long as the
cage is in the straight part of its path, but when the cage is passing from side to
side at the top and at the bottom, further provisions are requisite to control the
lower part of the cage.
The sling link when it passes on to the chain wheel either at the top or at the
bottom becomes securely held, and as the link is carried around, the arms bearing
the rollers remain radial to the wheel, and the rollers consequently roll accurately
around the guides as they curve over or under the chain wheel, but at the bottom
of the cage the wheels being on an axis which remains always horizontal, would
not roll around curved guides; these guides are therefore discontinued at the top and
bottom, and the control of the lower part of the cage is effected by a wheel at a
suitable distance below the chain wheel. This wheel is connected with the chain
wheel by gearing so that it revolves it unison; it has recesses in its periphery, and
as each cage comes round a strong stud with suitable collars upon it fixed to the
back of the cage (near the bottom and vertically beneath the point of suspension)
enters one of the recesses in the controlling wheel, and so the bottom of the cage
becomes held, and the wheel carries it round in its proper course.
The guides for the lower rollers, are provided with self-acting traps near their
lower ends to allow of the passage through them of the projecting portion of the
sling links by which the cages are suspended.
Sometimes it is convenient to employ two endless chains, and to carry the cages
between them.
In some cases in order to avoid the necessity for the controlling wheels and
studs, I mount the axis of the lower pair of rollers upon a pivot on the back of the
cage, and I compel this axis to remain constantly parallel to the roller carrying
arms of the sling link by means of a pair of small chain wheels and a pitch chain.
I also continue the axis of the lower rollers to the centre line of the apparatus, and
at the end of the axis I form a stud or projection, which at the upper and the
lower end of the course of the cage enters between guides provided for it. I also in
this arrangement continue the guides for the lower rollers around the top and the
bottom in the same way as the guides for the top rollers are carried round from the
ascending side to the descending side.
According to another arrangement
substitute for the endless chains to carry
the cages a series of toothed wheels mounted upon axes one over the other to the
height desired. The cages are formed with racks upon their sides, and by gearing
with these racks the toothed wheels propel the cages up and down in suitable guides
which are provided to control them. There is space enough left between the axes
at the top and at the bottom to allow the cages to pass under the upper axis and
above the lower one.
When the cage approaches its uppermost position, pins or round teeth at the
corners of the cage enter between the teeth of the wheels, and the cage hangs by
these pins, and is raised and carried laterally by them until it gets to the top. At
this point the wheels still revolving come into gear with racks fixed across the
bottom and the top of the cage, and so the cage is traversed from side to side until
pins at its other corners (which form the terminal teeth of the horizontal racks at
the top and bottom) engage with the teeth of the wheels; and then hanging from
the wheels by these pins the cage is carried sideways, and at the same time lowered
until the teeth of the wheels on the axis, which is then level with the bottom of
the cage, begin to gear into the racks upon the cage side. The cage afterwards
descends in a straight course until it reaches the bottom, when the operation of
passing across is repeated, and everything takes place in a manner so similar to.
that which happens in the upper passage already described, that no further.
description is requisite.
In the arrangement above described, in place of the intermediate toothed wheels,,
pitch chains passing over chain wheels at either end can be employed, and in either.

page_text: case it is possible to stop a cage at any part of its course by providing other toothed
wheels on the outer side to gear with the racks and support the cage, whilst by
moving switches forming part of the guides, the racks on the inner side of the cage
are allowed to fall out of gear with the toothed wheels of the main series, or with
the pitch chains which may be substituted for these wheels.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frederick Hart in the Great Seal Patent Office on the 5th July
1878.
FREDERICK HART, of 59, Tavistock Road, Westbourne Park, W., Consulting
Engineer. "IMPROVEMENTS IN ELEVATORS."
This Invention has for its object improvements in elevators, and relates especially
to that class of elevators in which a series of cages suitable for receiving passengers
or goods are kept in continuous motion, ascending on one side and descending on
the other side.
The cages are carried by an endless chain passing around chain wheels at the top
and bottom, and one of these chain wheels is driven by an engine which is suitably
controlled. The cages stand in front of the chain, and are suspended by means of
sling links introduced into the chain at the places required. There is a sling link
for each cage, and the link carries a pin projecting out from it horizontally and at
right angles to the plane in which the chain travels. This pin enters an eye formed
for it centrally in the back of the cage, at the upper part, and by it alone the cage
hangs. Both in ascending and in descending the cage is guided by rollers or small
wheels running on guides of angle iron. One pair of rollers carried by arms on the
sling link controls the tendency of the upper part of the cage to fall forward, and at
the same time steadies the cage laterally.
Another pair of rollers upon an axis fixed to the lower part of the cage, and
running upon other angle iron guides (set in front of the first pair of guides) pre-
vents the lower part of the cage tipping towards the back, which if free it would do
in consequence of the point of suspension being in rear of the centre of gravity of
the cage. Thus the guiding of the cage is effectually provided, for so long as the
cage is in the straight part of its path, but when the cage is passing from side to
side at the top, and at the bottom, further provisions are requisite to control the
lower part of the cage.
The sling link when it passes on to the chain wheel, either at the top or at the

page_text: bottom, becomes securely held, and as the link is carried around, the arms bearing
the rollers remain radial to the wheel, and the rollers consequently roll accurately
around the guides as they curve over or under the chain wheel, but at the bottom of
the cage, the wheels being on an axis which remains always horizontal, would not
roll around curved guides; these guides are therefore discontinued at the top and
bottom, and the control of the lower part of the cage is effected by a wheel at a
suitable distance below the chain wheel. This wheel is connected with the chain
wheel by gearing so that it revolves in unison; it has recesses in its periphery, and
as each cage comes round a strong stud with suitable collars upon it fixed to the
back of the cage (near the bottom and vertically beneath the point of suspension)
enters one of the recesses in the controlling wheel, and so the bottom of the cage
becomes held and the wheel carries it round in its proper course.
The guides for the lower rollers are provided with self-acting traps near their
lower ends to allow of the passage through them of the projecting portion of the
sling links by which the cages are suspended.
Figure 1 is a front elevation, and Figure 2 is a side elevation of an elevator con-
structed in this manner.
A, A, is metal framework firmly fixed to the wall of the building at the top and
bottom of the shaft in which the elevator is intended to work; B, B, and C, C, are
angle iron guides which are also firmly fixed; the arrangement of these guides at
the top and bottom is seen in the Drawings, and they are continuous throughout
the intermediate space in the shaft whatever may be its height; D and E are chain
wheels mounted upon axes upon the frames at the top and bottom; F is an endless
chain passing around the wheels D and E, and the projections or teeth of the wheels
engage with the links of the chain. The lower chain wheel E is driven by a
bevilled pinion upon the vertical shaft G which takes its motion from a steam or
other engine and is suitably controlled, so that it always revolves at a uniform
speed. The pinion upon this shaft engages with teeth formed upon the wheel E,
and the wheel transmits motion to the chain, and so to the upper wheel D; H is the
cage, its construction and arrangement in relation to other parts in immediate con-
nection with it will be more clearly understood on reference to the detail, Figures a
and b.
Figure a is a vertical section of the cage with other parts, and Figure 6 is a plan
partly in section of the same. There may be one, two, or more cages employed,
according to the requirements. The cage is a strong case open in front; it has an
iron bar H¹ serving as a back bone upon which it is built, and when it is intended
for the conveyance of passengers it is of sufficient height to admit of a man standing
erect within it. At the upper end of the bar H³, and to the back thereof, a long
bearing is fixed to receive the horizontal pin or axis F¹, by which alone the cage is
suspended. The pin or axis F¹ is fixed in the middle of one of the links F2 of the
chain F which as it is the link from which the cage is slung I call the "sling link."
The sling link also has two arms projecting outwards from its centre at right angles
to the length of the link, and also at right angles to the pin or axis F, and these
arms serve as axles for the guide rollers F³, F. These guide rollers roll along the
backs of the angle iron guides B, B, and so control the tendency of the cage to tip
forward at the top. The guides B are, as the Drawings indicate, curved round
both at the top and bottom, so that a continuous bearing surface is provided for the
rollers F
At the lower end of the bar H' of the cage an horizontal axle H is fixed, and
upon it are the guide rollers H³, H³. These guide rollers roll along the front of the
angle iron guides C, C, and so control the tendency of the lower part of the cage to
tip to the rear. The guide rollers HS leave the guides C when the cage is at the
top and bottom, the guides stopping short, and at these places other instruments
are provided for controlling the lower part of the cage. I is a stud fixed to the
bar H, near its lower end; this stud as the cage comes round engages with the
wheels K and L, entering notches which are formed in the periphery of the wheels

page_text: for the reception of the stud. The wheels K and L are driven in unison with the
wheels D and E respectively by means of bevilled teeth formed upon the wheels
gearing with two pinions fixed upon the same vertical axis.
In the case of the lower pair the driving shaft G serves also to couple the
wheels E and L. By thus driving the wheels K and L the accurate presentation
of the notch to the stud is ensured, and the stud when caught is carried along the
M and N are
path it should take in order that it may properly control the cage.
traps in the inner front guides C, C. They are parts which are made moveable
in order that the pin F¹ and its bearing may be able to pass these guides when
the cage is moving from side to side at the lower part of its course.
Both of the
traps are weighted, so that they tend to close of themselves. The trap M is opened
by a projection fixed to the cage, which descends against the tail M¹ formed upon
the trap, and the trap N is opened directly by the parts which it is intended to
allow to pass.
Sometimes it is convenient to employ two endless chains, and to carry the cageз
between them.
In some cases in order to avoid the necessity for the controlling wheels and
studs I mount the axis of the lower pair of rollers upon a pivot on the back of
the cage, and I compel this axis to remain constantly parallel to the roller carrying
arms of the sling link by means of a pair of small chain wheels and a pitch chain.
I also continue the axis of the lower rollers to near the centre line of the apparatus,
and at the end of the axis I form a stud or projection, which at the upper and
the lower end of the course of the cage enters between guides provided for it. I
also in this arrangement continue the guides for the lower rollers around the top
and the bottom in the same way as the guides for the top rollers are carried round
from the ascending side to the descending side.
Figure 3 is a front elevation, and Figure 4 is a side elevation of an elevator
constructed in this manner. Figures c, d, and e are detail views of the cage and
parts in more immediate connection with it.
Figure c is a back elevation; Figure d is a side elevation; and Figure e is a
plan, partly in section.
A, A, is the fixed metal framework; B, B, are the guides for the top guide
rollers, which are carried by the sling link in the manner already described, with
the difference only that in this arrangement the guides B are set closer together,
an arrangement which admits of flat guides without side flanges being employed;
C and C are the guides for the bottom rollers. The wheels K and L are in this
arrangement dispensed with, and in place thereof the lower guide rollers are carried
by a moving part O, which is pivotted to the back of the cage at 0¹. 0$, 0%, are
the rollers, which run upon the guides C, C'. These guides like the top guides B
are continuous, being curved or arched round at the top and bottom. The
rollers 0, 0, are made to roll truly around the curved course, and the requisite
movement of the part O is obtained by connecting it with the sling link in such
manner as to keep the axles of the top and bottom guide rollers always parallel
the one to the other. A chain wheel P is mounted upon the sling link around
the point of suspension of the cage, and upon the pivot or axis O₁ of the part o
there is another similar chain wheel P'. An endless pitch chain Q encircles the
wheels P and P₁, and causes them to rotate at the same time and at the same
speeds.
In order further to control the movement at the top and bottom and ensure the
guide rollers remaining upon the guides, taking a truly circular course around a
central point, the part O is continued to the centre at 08, where it terminates in a
Tor cross head. At the ends, both at top and bottom, the guides C are adapted
to receive this cross head to guide it to the centre point and there retain it whilst
the turning motion is taking place.
The guides C and C¹ have openings at the points where they are crossed by the
path of the axis, from which the cage is suspended. The openings at the top.

page_text: through the guides C¹ need not be provided with traps, for the part O being
formed to take a bearing upon the guide whilst the guide roller passes the gap the
roller cannot fall in. At the bottom I provide small counterbalanced traps to the
openings in the guide C; they are so arranged as to yield to the lateral pressure
of the parts they are intended to allow to pass. These traps also may in some
cases be dispensed with.
Two endless chains carrying the cages suspended between them may also be
employed on this system. The cages then are open at the sides for entrance and
exit, and separate landings are provided on the entrance and exit sides.
According to another arrangement I substitute for the endless chains to carry
the cages a series of toothed wheels mounted upon axes one over the other to the
height desired.
The cages are formed with racks upon their sides, and by gearing
with these racks the toothed wheels propel the cages up and down in suitable
guides, which are provided to control them. There is space enough left between
the axes at the top and at the bottom to allow the cages to pass under the upper
axis and above the lower one.
When the cage approaches its uppermost position, pins or round teeth at the
corners of the cage enter between the teeth of the wheels, and the cage hangs by
these pins and is raised and carried laterally by them until it gets to the top. At
this point the wheels still revolving come into gear with racks fixed across the
bottom and the top of the cage, and so the cage is traversed from side to side until
pins at its other corners (which form the terminal teeth of the horizontal racks at
the top and bottom) engage with the teeth of the wheels, and then hanging from
the wheels by these pins, the cage is carried sideways and at the same time lowered
until the teeth of the wheels on the axis which is then level with the bottom of the
cage begin to gear into the racks upon the cage side. The cage afterwards descends
in a straight course until it reaches the bottom, when the operation of passing across
is repeated, and everything takes place in a manner so similar to that which happens
in the upper passage already described that no further description is requisite.
In the arrangement above described; in place of the intermediate toothed wheels,
pitch chains passing over chain wheels at either end can be employed. And in either
case it is possible to stop a cage at any part of its course by providing other toothed
wheels on the outer side to gear with racks and support the cage, whilst by moving
switches forming part of the guides, the racks on the inner side of the cage are
allowed to fall out of gear with the toothed wheels of the main series, or with the
pitch chains which may be substituted for these wheels.
Figure 5 is a front elevation; and Figure 6 is a side elevation showing this
arrangement.
Figure 7 is a section through the cage taken on the line A, B, in Figure 5.
A and A¹ are the guides which are firmly fixed within the shaft in which the
elevator works. The outer guide A is continuous up one side of the shaft, over the
top, down on the other side of the shaft, and across the bottom to the starting point,
it has openings in it to allow the guide rollers on the cage to enter, and leave the
guide at certain points, as herein-after appears. The inner guides A¹, A¹, terminato
short of the top and the bottom of the shaft, so that the cage is free from them at
the time it moves laterally; B, B, are the cages; B', B¹, are guide rollers, four on
each cage; B, B2, are racks fixed to the cage at the sides, top, and bottom.
C, C, are toothed wheels, so placed as to gear with the side racks B³ on the cages.
The wheels C are driven by the vertical shaft D, which has bevilled pinions upon it
engaging with bevilled wheels on the same axes with the wheels C, as the Drawings
indicate. Thus the cages when they are in the guides on one side of the wheel C
are raised, and when in the guides on the other side of the wheels C, they are
lowered; and in this way the vertical motion of the cages is obtained from top to
bottom of the shaft, both in ascending and descending.
C' is a toothed wheel, also driven, which when the cage comes to the top, engages
with a pin forming the terminal tooth of the rack running along the top of the

page_text: cage, and the guide A being rounded at the top corner, the wheel is kept in gear with
the pin until this pin has mounted to the top of the wheel. At the same time the
corner pin at the bottom of the cage mounts up the wheel C with which it is in gear,
and as the motion continues, both wheels come to gear with the horizontal racks on
the cage, and so the cage is carried sideways until it is brought to a position to
descend on the other side.
If it be desired arrangements may be made which admit of a cage being
withdrawn when desired, this is useful, for example, where goods have to be
conveyed which require time to load and unload. All that is requisite for
this purpose is to make parts of the outer guide moveable, and to provide
other tooth wheels to gear with the racks on the cages for the purpose of car-
rying them in and out. Thus at A* there is a portion of the top guide A
forming the corner which is capable of turning about an horizontal axis in order
that it may be set either to direct the rollers B' into the vertical guide, in order
that the cages may descend, as already described, or into an horizontal continuation
of the top guide. Again A** is a portion of the vertical guide which can be turned
down into an horizontal position, moving about a joint at its lower end, so as to
permit the cage to pass out, and to receive the bottom rollers B¹ as it does so. E, E,
are toothed wheels which can at pleasure be driven in either direction. They are
set into motion in one direction, when it is desired to withdraw a cage, and in the
other for the purpose of returning the cage into the elevator shaft.
As before mentioned, endless chains so formed as to engage with the racks on the
sides of the cages may be substituted for the toothed wheels C in the intermediate
parts of the system.
Having thus described the nature of my said Invention, and the manner of per-
forming the same, I would have it understood that I claim,―
First. The method of guiding the cages by means of a sling link, with the sus-
pending axis in the middle of the link, and with transverse arms projecting from
the link and carrying guide rollers, substantially as described in respect to Figures 1,
2, 3, and 4, and the detail Figures corresponding therewith.
Second. The means of controlling the lower part of the cage when the cage is
travelling laterally at the top and bottom of the shaft by a wheel driven at a
suitable speed, and engaging with a stud upon the cage, substantially as described
in respect to Figures 1 and 2, and the detail Figures corresponding therewith.
Third. The construction of elevators, substantially as described in respect to
Figures 1 and 2, and the detail Figures corresponding therewith.
Fourth. The means of controlling the guide rollers at the lower part of the cage,
by coupling the axes of the lower guide rollers with the sling link, in such a manner
as to cause them to incline with it, substantially as described in respect to Figures
3 and 4, and the detail Figures corresponding therewith.
Fifth. The means of controlling the lower part of the cage when travelling later-
ally at the top and bottom of the shaft, by providing a projection in connection
with the axes of the lower guide rollers reaching to the centre, and retained there
whilst the turning motion is taking place, substantially as described in respect to
Figures 3 and 4, and the detail Figures corresponding therewith.
Sixth. The construction of elevators, substantially as described in respect to
Figures 3 and 4, and the detail Figures corresponding therewith.
Seventh. The means of operating the cages of elevators by means of racks upon
them engaging with the teeth of wheels, or pitch chains actuated by a motive-power
engine, substantially as described in respect to Figures 5, 6, and 7.
Eighth. The means of effecting the transfer of the cages from the ascending to
the descending side of the shaft by horizontal racks on the cages mounting up and
travelling over toothed wheels which engage with them, substantially as described
in respect to Figures 5, 6, and 7.
Ninth. The means of withdrawing a cage from the elevator shaft, and returning
it thereto, substantially as described in respect to Figures 5, 6, and 7.

page_text: Tenth. The construction of elevators, substantially as described in respect to
Figures 5, 6, and 7.
In witness whereof, I, the said Frederick Hart, have hereunto set my hand
and seal, this Fifth day of July, in the year of Lord One thousand eight
hundred and seventy-eight.
F. HART. (L.S.)