Improvements in or connected with Hoists or Lifts.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in or connected with Hoists or Lifts.
We, ALEXANDER BEWICKE BLACKBURN, Manager of the Electric Construction
Company Limited, and WILFRID L. SPENCE, Civil Engineer, of Dunluce, Tetten-
hall Road, both of Wolverhampton, Staffordshire, do hereby declare the nature of
this invention to be as follows:-
This invention relates principally to suspended hoists or lifts of the counter-
balance type, working either vertically or on an incline, in which the dead weight
of the cage, or platform, and usually also some portion of the load, is or are.
wholly, or partially, balanced, and it has for its objects to increase the efficiency
and durability of the hoist or lift, while reducing both the cost of the hoist or
lift and the space occupied by the winding apparatus.
It has been usual, in what have hitherto been considered the best suspended
hoists or lifts, to wind the hauling rope, or ropes, on to a helically grooved drum,
to balance the cage, or platform, only by a rope passing over a loose sheave direct
to the balance weight, and to use a third rope to balance a portion of the load,
this rope being attached to the cage, or platform, on the one hand, and being
wound on a helical groove drum, in the reverse way to the main hauling rope,
on the other hand. The objections to this arrangement are that it is costly, that
it occupies considerable space, especially for long lifts, and that the lead" of
the rope alters as the cage or platform is raised, or lowered. Some of these
objections are minimised in the grip sheave type using only a single rope, or set
of ropes, attached to the cage or platform at one end and to the counter-balance
at the other end, and passing half round the driving wheel. A modification of
this method, designed to reduce the slip, is to take the ropes half round the driv-
ing pulley, then over a skew sheave to give the necessary "lead," back a second
time to the driving pulley, passing half round it, and finally to the balance
weights.
Some of these methods have been used in connection with a right and left hand
combination worm gear furnishing the power, but as they depend on a single
winding drum, or on a pair of drums on one shaft, it is necessary to gear the
right and left hand worm wheels together and transmit one half the power through
the teeth in contact. This obviates all end thrust on the worm shaft but entails
loss and wear on the worm wheels.
In the arrangement according to this invention the duplex worm gear with
right and left hand threads is retained, and there is used in combination there-
with, two or more grooved friction grip sheaves, or the like, one fixed on each
wheel shaft and so arranged that each performs exactly, or approximately, one
half of the work in hoisting, or lowering. Thus there is no transmission from one
wheel to the other and consequently no necessity to gear them together.
As a precautionary measure however we find it convenient in certain cases to
let the wheels run together although under normal conditions this meshing has
no useful function, it therefore does not entail any appreciable loss, or wear.

page_text: When the hoisting machine is overhead and symmetrically over the well, an
arrangement according to this invention may be as follows:-Two ropes, or sets.
of ropes, are used each carrying one half the total balance weight. One rope,
or set of ropes, rises from the left hand of the cage or platform passing to the
right hand over and round the sheave at the left hand side and is led away on
the left hand side over a loose pulley (which should be slightly skewed) to the
balance weight. The other rope, or set of ropes, rises from right hand side of the
cage or platform and passes to the left hand over and round the sheave at the right
hand side and is led away to the right hand side over a loose pulley and to its
balance weight: This involves balance weights on each side of the elevator which
is not always convenient. When the counter-balance must be entirely on one
side, say the left, the following arrangement may be adopted:-The left hand
rope, or set of ropes, passes as in the foregoing arrangement but the right hand
rope or set of ropes passes over its sheave, then under another sheave fixed on the
left hand sheave shaft, and finally is led away over a loose pulley to the counter-
balance. In the aforesaid arrangements the two ropes, or sets of ropes, may
be attached to opposite ends of a weigh beam from the middle of which the cage
is suspended as this will tend to compensate for any slight difference in the
effective diameters of the driving sheaves. A. similar arrangement may be used
for the attachment of the ropes or sets of ropes to the balance weights.
When the winding machine is at the bottom of the lift space this invention
may be applied as follows:-
A single endless rope or set of ropes is used, the rope run being from the top
of the cage or platform over the upper loose pulley down to the balance weight,
from the balance weight down to one driving sheave, under it, and then over and
partly around the second driving sheave and away to the lower loose pulley and
then up to the under side of the cage or platform. Of course the cage or platform
may take the place of the balance weight and the balance weight may take the
place of the cage or platform in the foregoing arrangement. Any usual means
may be provided for tightening the ropes as they stretch or the whole winding
machine may be mounted on slides and be drawn away as in a belt tightening
device.....
1.
It will be obvious that by adding a second loose sheave overhead the tail rope
connecting the under-side of the cage and balance may be done away with. . În
this case the rope run may be from the cage up to one sheave; down to the winding
"machine, under one driving wheel, over and partly round the other, away to the
lower guiding pulley, up to the second overhead sheave and finally down to the
balance.
"
This arrangement is applicable also when the winding machine has to be placed
on an intermediate floor, and with slight modification when the machine is over-
head:
"
.
t
The foregoing arrangements are among the simplest that can be adopted, each
provides for a gripping surface practically equal to, or greater than, one complete
turn round the driving pulley which is ample even for high speed service, the
width of the machine is very much less than that of the drum type, there is no end
thrust on the worm shaft and no transmission from one wheel to the other, and
while the cost is comparatively small the efficiency may be the highest attainable.
Various other modifications can of course be made, but in all cases it is practic--
able to arrange that the two driving sheaves shall share the work equally and at
the same time afford adequate gripping surface, which can always be increased
if required by suitable guiding pulleys, we therefore do not limit ourselves to the
precise arrangements' given as examples.
Here
The same principle is readily applied to drum 'winding machines, where direct
counter-balancing is impracticable, as for example in a warehouse jib crane.
the hoist chain may be wound on a barrel fixed to one worm wheel shaft and the
counter-balance chain, with very limited travel, may be wound on a barrel of
smaller diameter fixed to the other wheel shaft, the relative weights of average

page_text: load and of counter-balance being designed to minimise the transmission from one
wheel to the other. In other cases as, for example, travelling cranes, counter-
balancing is entirely inadmissible, but two "chain" barrels may be used to equally
share the load and obviate end thrust on the worm shaft: "
413 *
Dated this 8th dor of In 1907
{"
Improvements in or connected with Hoists or Lifts.
T
We, ALEXANDER BEWICKE BLACKBURN, Manager of the Electric Construction
Company Limited, and WILFRID L. SPENCE, Civil Engineer, of Dunluce, Tetten-
hall Road, both of Wolverhampton, Staffordshire, 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 invention relates principally to suspended hoists or lifts of the counter-
balance type, working either vertically or on an incline, in which the dead weight
of the cage, or platform; and usually also some portion of the load is, or are,
wholly, or partially, balanced, and it has for its objects to increase the efficiency
and durability of the hoist or lift while reducing both the cost of the hoist or
lift and the space occupied by the winding apparatus.
It has been usual, in the best suspended lift practice to wind the hauling
rope, or ropes, on to a helically. grooved drum, to balance the cage, or
platform only, by a rope passing over a loose sheave direct to the balance weight,
and to use a third rope to balance a portion of the load, this rope being attached
to the cage, or platform, on the one hand, and being wound on a helical groove
drum, in the reverse way to the main hauling rope, on the other hand. The
objections to this arrangement are that it is costly, that it occupies considerable
space, especially for long lifts, and that the "lead" of the rope alters as the cage
or platform, is raised, or lowered. Some of these objections are minimised in the
grip-sheave type using only a single rope, or set or ropes, attached to the cage or
platform. at one end and to the counter-balance at the other end, and passing
half-round the driving wheel. A modification of this method, designed to reduce
the slip, is to take the ropes half round the driving pulley, then over a skew sheave
to give the necessary. "lead," back a second time to the driving pulley, passing
half round it, and finally to the balance-weights.
.
Some of these, methods have been used in connection with a right and left hand
combination worm gear furnishing the power, but as they depend on a single
winding drum, or on a pair of drums on one shaft, it is necessary to gear the
right and left hand worm wheels together and transmit one half the power through
the teeth in contact. This obviates all end thrust on the worm shaft but entails
loss and wear on the worm wheels.
17.
In the arrangements according to this invention the duplex worm gear with
right and left hand threads is retained and there are used, in combination there-
with, two, or more, grooved friction grip sheaves, or the like, one fixed on each
wheel shaft and so arranged that each performs exactly, or approximately, one
half of the work in hoisting or lowering. Thus there is no transmission from one
wheel to the other and consequently no necessity to gear them together.
As a precautionary measure, however we find it convenient in certain cases to
let the wheels run together or to couple the two shafts together by independent

page_text: gearing although under normal conditions this meshing has no useful function,
it therefore does not entail any appreciable loss, or wear.
We will describe our invention with reference to the accompanying drawings
which illustrate diagrammatically various arrangements according to our inven-
tion, the right and left hand worm gears however not being shewn as they are
well understood.
When the hoisting machine is overhead and symmetrically over the well, an
arrangement according to this invention may be as illustrated by Figures 1 and 2.
Two ropes, or sets of ropes A, A', are used each carrying one half the total balance
weight. One rope or set of ropes A rises from the left hand of the cage or plat-
form B passing to the right hand over and round the sheave C at the left hand side
and is led away from beneath the sheave over a loose pulley D, which should be
slightly skewed as shewn in Figure 2, to the balance weight E. The other rope or
set of ropes A' rises from the right hand side of the cage or platform B and passes
to the left hand over and round the sheave C₁ at the right hand side and is led
away from beneath the sheave over a loose pulley D₁ to its balance weight E¹.
This arrangement involves balance weights on each side of the elevator which
is not always convenient. When the counter-balance must be entirely on one
side, say the left, the arrangement illustrated by Figure 3 may be adopted:
The left hand rope or set of ropes A passes, as in the foregoing arrangement, round
the sheave C, and over the loose pulley 1) to the counter-balance weight E, but
the right hand rope or set of ropes A¹ passes over its sheave C¹ then under another
sheave similar to the sheave C and fixed on the left hand sheave shaft, and finally
is led away over a loose pulley such as D to a counter-balance weight. In these
two arrangements as in all others the ropes may be attached (as shewn) to opposite
ends of a weigh beam F from the middle of which the cage or platform B is sus-
pended, as by this arrangement any slight difference in the effective diameters
of the driving sheaves C C will be compensated for. A similar arrangement may
be used for the attachment of the ropes to the balance. weights, and compound
equalising levers or weigh beams may be employed.
Figure 4 shews an arrangement according to our invention when the winding
machine is at the bottom of the lift space.
A single rope A or set of ropes is used, the rope run being from the top of the
cage or platform B over an upper loose pulley G down to the balance weight E
from the balance weight down to and under one driving sheave C, then over and
partly around the second driving sheave C¹ and away to a loose pulley D and
thence up to the under side of the cage or platform to which it is attached. Of
course the cage or platform B may take the place of the balance weight E and the
balance weight may take the place of the cage or platform in the foregoing
arrangement.
Any usual or suitable means may be provided for tightening the ropes as they
stretch or the whole winding machine may be mounted on slides and be drawn
away as in a belt tightening device.
In the arrangement illustrated by Figure 5 a better adhesion of the rope on the
sheaves is obtained. In this arrangement there is a second loose overhead
sheave G¹, the ropes A in this arrangement being connected at one end to the cage,
pass up and over the sheaves G¹, down to and under one driving sheave or pulley C
of the winding machine, over and partly round the other sheave or pulley C
away to the lower guiding pulley D, up to the second overhead sheave G and
finally down to the balance weight E.
7.
This arrangement is applicable also when the winding machine is placed on an
intermediate floor, and with slight modification when the machine is overhead.
Figures 6 and 7 represent in elevation and plan respectively an arrangement
similar to Figure 5 both arrangements being also applicable when the winding
machine is situated on an intermediate floor.
The foregoing arrangements are among the simplest that can be adopted, each
provides for a gripping surface practically equal to, or greater than, one complete

page_text: turn round the driving pulley which is ample even for high speed service, the
width of the machine is very much less than that of the drum type, there is no end
thrust on the worm shaft and no transmission from one wheel to the other, and
while the cost is comparatively small the efficiency may be the highest attainable.
Where the machine has to be fixed on an intermediate floor and skew guiding
pulleys are undesirable, a separate hauling rope A may be provided as illustrated
in Figure 8. The balance rope A2 in this arrangement passes up from the top of
the cage or platform B over the overhead sheave G down to the balance weight E,
terminating there, and recommencing at the underside of the balance weight
passes down and under the lower sheave G¹ to the bottom side of the cage or plat-
form B. The hauling rope A passes from the top side of the balance weight E
over the upper sheave G, directly down to and under one driving sheave Ci over
the other driving sheave C past the guide pulley D, under the lower sheave G¹
and terminates at the lower end of the balance weight E. Figure 9 illustrates
the simplest and usually preferred arrangement when the winding mechanism is
overhead. A single rope A or set of ropes is attached to the cage or platform and
passes up over one driving sheave C and then under and round the other driving
sheave C¹ thence over a guide pulley D down to the balance weight E.
Various other modifications can of course be made, but in all cases it is practic-
able to arrange that the two driving sheaves shall share the work equally and at
the same time afford adequate gripping surface which can always be increased
if required by suitable guiding pulleys we therefore do not limit ourselves to the
precise arrangements given as examples.
Figure 10 shews the arrangement illustrated in Figure 9 as applied to a ware-
house jib crane. The load B and counter-balance weight E which may both
require to be guided to prevent twisting of the ropes are each hung from multiply-
ing rope blocks H so that the hauling rope A travels at a greater speed than that
at which the load is raised and lowered. This has the advantage that the driving
sheaves or drums C C¹ run at a much higher speed and the worm gear ratio is
correspondingly less. This arrangement is of course applicable to elevators and the
like. With reference to the whole of the drawings, it is to be clearly understood
that these are purely diagrammatic. The cages in most of the figures are shewn
proportionally too large and the overhead sheaves too small.
The same principle is applicable to drum winding machines but we wish it to
be understood that we make no claim to any arrangement in which a rope or chain
or ropes or chains is or are continuously coiled round either one or both driving
drums.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
م:
1. In or connected with balanced hoists or lifts the combination with a duplex
right and left hand worm and worm wheel gear of two drums mounted on the worm
wheel shafts and adapted to drive by frictional adhesion one or more winding or
hauling ropes which pass over them in such a manner as to tend to equally load
both worm gears without making one complete turn round either drum, sub-
stantially as and for the purposes described.
2. In or connected with balanced hoists or lifts, the combination of duplex right
and left hand worm and wheel gear, non-helically grooved drums carried on the
worm wheel shafts, and a system of hauling ropes passing round, but not con-
tinuously wound upon, the drums, and so arranged while securing adequate
adhesion by the equivalent of one complete turn round one drum as to distribute
the load over both drums and minimise end thrust on the worm shaft, substantially
as and for the purposes herein before described.
3. In or connected with balanced hoisting or winding apparatus the combina-
tion with duplex right and left hand worm and wheel gear, of two drums mounted
on the worm wheel shafts grooved in parallel planes and geared together by the

page_text: hauling rope or ropes so as to minimise end thrust on the worm shaft, sub-
stantially as and for the purposes set forth.
4. The improvements in suspended hoists or lifts, substantially as and for the
purposes described.
5. The arrangements of duplex right and left hand worm and wheel gear, rope
drums and ropes, substantially as hereinbefore described and illustrated 'by
Figures 1 and 2, Figure 3, Figure 4, Figure 5, Figures 6 and 7, Figure 8,
Figure 9 and Figure 10 of the accompanying drawings.
Dated this 6th day of April 1898.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents."