Improvements in Electric Elevators...
Year: 1897

page_text: Date of Application, 31st Dec., 1897
Complete Specification Left, 30th Sept., 1898-Accepted, 23rd Dec.,
1898
[Communicated from abroad by FRANK J. SPRAGUE, of No. 20, Broad Street,
New York City, United States of America, Manufacturer.]
Improvements in Electric Elevators...,
I, HENRY HARINGTON LEIGII, Assoc. M. Inst. C.E., Fel. Ch. Inst. P.A.,
F.I. Inst., practising as Phillips & Leigh, of No. 22, Southampton Buildings,
Chancery Lane, in the Administrative County of London, Engineer and Patent
Agent, do hereby declare the nature of this invention to be as follows:-
The present invention relates to improvements in electric elevators, and
comprises improvements in the hoisting mechanism used in elevators driven by
electro-motors, and particularly the mechanism employed in transmitting the
power from the motor to the winding drum of the hoisting machine. It also
covers a particular construction of idler sheaves, whereby they are carried from
side to side so as to preserve them in line with the points at which the ropes wind
from the drum; and further; improved safety devices in connection with the
ropes and the drum, whereby any slackening of the ropes leading to the drum,
or improper winding upon the drum, will cause the opening of a switch whereby
the mechanism will be stopped.
In the accompanying drawings, which form a part of this specification,
Figure 1 is a plan view showing the hoisting machine and idler sheaves under
which the cables are led to the counterweight, the safety devices and the covers
for the driving gears being omitted and the idler sheaves and bevel gears being
in section ;
Figure 2 is a side elevation showing the hoisting mechanism and vibrating,
sheaves, the base of the machine being in section on the line of one of the worm-"
shafts, and the outer bearing for the screw which supports the vibrating sheaves
removed;
Figure 3 is an elevation of the end of the hoisting machine on which the motors
are located.
In its general features, the hoisting mechanism consists of a winding drum 1
suitably mounted, and driven by two motors 2 through the agency of worm
gearing. The armature-shafts of the motors are directly coupled to the worm-
shafts 3 of the hoisting mechanism. There are two worm-shafts, each connected
to one of the motors. Each worm-shaft is provided with two worms 4 which
engage with worm-wheels 5 mounted on two parallel shafts 6 and 7 which are
geared together by spur-gears 8. The drum is mounted upon one of the worm-
wheel shafts the other shaft being added to balance the thrusts on the worm-
shafts.
The shaft connected with each motor carries a right-hand worm and a left-
hand worm. Their end thrusts are therefore always opposed to each other and
completely balanced, so that no thrust bearings are necessary on the shafts.
The worms on the two worm-shafts are reversed with respect to each other, so
that a right-hand worm on one shaft is opposite a left-hand worm on the other

page_text: .
shaft. Since the worm-wheels are cut right and left to engage with the worms,
it follows that the worm-wheels on each shaft will also be reversed with respect
to each other. Owing to the obliquity of the teeth on the wormi-wheels, they
also have a thrust in the direction of their shafts, but the thrusts of the two-worm-
wheels on each shaft are equal and opposed to each other, so that no thrust
bearings are needed on the worm-wheel shafts.
The worm-wheel shafts are coupled by two pairs of spur-gears 5 and 8. In
order to secure the perfect meshing of all the gears with respect to each other,
at least two of the spur-gears and two of the worm-wheels are not keyed. fast to
their shafts when the machine is first assembled, but are bolted to flanges which
are keyed to the shafts. The bolts pass through oval, holes in the gears, so that
the gears may slip around with respect to their shafts such slight amount as
may be necessary to bring them into correspondence with the remaining gears.
While thus mounted, it is necessary to run the train of gearing for some time
before it is put into use, in order to allow the teeth to adjust themselves into
correct relative spacing with respect to each other. When this has been accom-
plished, the gears, which were at first held only by the bolts, are rigidly secured
by dowel pins.
In order that the cables may be carried horizontally from the hoisting machine to
the point where they may rise in the well, either for the car or a counterweight,
it is necessary to provide idler sheaves 9. To avoid leading the cables to the
idler sheaves obliquely, these sheaves must be mounted so that they shall be
carried laterally as the cables wind or unwind from the drum. To do this there
is provided a threaded shaft 10 which is positively driven from the hoisting
machinery through the bevel gears 1, shaft 12, and bevel gears 13. The threaded
shaft engages two nuts 14, which are held against rotation by arms 15 engaging
with a guide rail 16. These nuts serve as bearings for the idler sheaves. As
shown, the shaft is provided with a right-hand and left-hand. thread, it being
intended to carry two sheaves engaging with ropes which unwind from right-
hand and left-hand grooves on the drum. The parts which carry the iller
sheaves are mounted on a separate base from the hoisting-machine, and will
usually be at a greater distance than shown. The two pairs of bevel gears may
therefore be at a considerable distance from each other, and the connecting
shaft 12 will consequently have to be of such length as may be required.
Two sets of cables are shown in connection with the hoisting-machine, each
consisting of four ropes, two of which lie adjacent in right-hand spiral grooves;
and two adjacent in left-hand spiral grooves upon the drum. The ends of the
cables in one of these sets 17 are anchored adjacent to the flanges of the drum,
and, as shown, lead directly up from the drum, and are intended to lead to the
The ends of the cables in the other set 18 are anchored to the drum near
its middle plane, and lead under the idler sheaves, and are intended to lead to the
counterweight.
car.
A safety device is provided, which is intended to stop the hoisting machinery
by opening the motor-circuit in case the cables should fail to wind properly upon
the drum, or in case the cables which lead to the car should become slack. This
safety device consists of a switch in the motor-circuit, the moveable arm 19 being
mounted on a rock-shaft 20. This switch-arm is pivoted to an arm on the rock-
shaft in such a manner that it may be opened independently of any movement
of the rock-shaft, but will be forced open in case the rock-shaft be operated.
Depending from the rock-shaft are arms 21 which carry a horizontal shaft 22 on
which are idler wheels 23 that bear against the cables leading from the drum.
Weights 24 on horizontal arms 25 from the rock-shaft cause these idler wheels
to press against the cables, and should the cables become slack; the rock-shaft
will revolve a sufficient distance to throw out the switch. Since the switch is
independently pivoted, the re-tightening of the cables, while it will return the
rock-shaft to its normal position, will not return the switch, and the latter will
remain open until closed by hand.

page_text: The parts operating in case of any of the cables failing to wind properly on the
drum are as follows: A bar 26 extends across the face of the drum, and in
such close proximity thereto that should any cable at any point fail to wind in
the bottom of its groove, and either lie across the ridge which separates adjoining
grooves, or on top of another cable, it will come in contact with this bar and move
it outward. This motion is transmitted through a vertical rod 27 to the switch,
and will likewise throw it open.
.
Strap-brakes 28 engage with drums on each of the worm-shafts to stop the
hoisting machine at the same instant with the failing of the current in the
motor-circuit. These brakes are applied by heavy springs 29. When the hoist-
ing machine is in operation, they are held off by the straightening of toggles 30,
which are connected to soft iron plungers 31 that nearly meet in the centre of a
coil of wire 32 in the motor-circuit. When a current is passing in this coil
of wire, the plungers are magnetized and attract each other, thus holding off the
brakes. But on the interruption of this current, the magnetism ceases in the
plungers, and the springs instantly apply the brakes.
Dated the 31st day of December 1897.
:
it
Improvements in Electric Elevators.
I, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E., Fel. Ch. Inst. P.A.,
F.I. Inst., practising as Phillips & Leigh, of No. 22, Southampton Buildings,
Chancery Lane, in the Administrative County of London, Engineer and 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:.
I
1
These improvements relate to the hoisting machines used in elevators driven
by electric motors, and particularly to the machines employed in transmitting
the power from the motors to the winding drum of the hoisting machine.
These improvements also relate to certain safety devices attached to the hoisting
machine for applying brakes to the driving shafts, and for stopping the machine
in event of the hoisting cables becoming slack, or the cables climbing out of the
grooves in which they are intended to wind on the drum.
There are two driving mechanisms separately driven by electric motors, each
being positively connected to the drum. Each driving mechanism has a worm-
shaft and two worm-wheel shafts, the drum being mounted on one of the worm;
wheel shafts. Each worm-wheel shaft has a flange attached thereto, and a spur-
gear ring and a worm-wheel ring are bolted to each flange. The spur-gear rings
intermesh with each other and the worm-wheel rings engage with the worms.
The bolt holes in one or more of the rings in each driving mechanism are elongated
to permit of circumferential adjustment of the rings, and thus allow the worm-
wheels to be brought into proper circumferential adjustment so as to mesh
properly with the worms, since proper meshing cannot be effected by endwise
adjustment of the worm-shaft, owing to the worms being of the Hindley type.
The same worm-wheel shafts are used for both driving mechanisms, and the
two mechanisms are thereby interconnected so that each will serve as a safety
to the other. This mechanism affords a positive connection between the two
motors which are employed, so that they are compelled to run synchronously,
and their armatures can be placed in series connection with the leads without
danger of one of the motors speeding up first and consuming the greater part of

page_text: the energy of the current.
This positive connection of motors, the armatures of
which are in series, is believed to be, broadly, new in electrically driven mechanism,
irrespective of whether the mechanism is employed in hoisting or for other uses.
It is to be distinguished from a case where two axles of a car are coupled to
motors which are connected in series, because the motors are not positively
connected, owing to the fact that the wheels can slip.
In the accompanying drawings, which form a part of this specification,
Figure 1 is an elevation of the machine viewed from the end at which the
motors are located.
Figure 2 is a plan view showing the hoisting machine with the covers for the
gearing removed.
Figure 3 is a side elevation of the machine.
Figure 4 is a detail view showing the connection between the slack-cable
safety and the switch.
Figure 5 is a detail view showing the connection between the cable-climbing
safety and the switch.
Figure 6 is a sectional view showing a spur-gear and worm-wheel and the
flange to which they are bolted.
In its general features, the hoisting mechanism consists of a winding drum 1
suitably mounted and driven by two electric motors 2, 3, through the agency
of positive gearing consisting of worm-gearing and spur-gearing. There are
two driving mechanisms, one located at each side of the hoisting machine, with
the winding drum between them. The mechanism to be seen at the lower side
in Figure 2, will be termed the right-hand driving mechanism, and the mechanism
to be seen at the upper side will be termed the left-hand driving mechanism.
The armature-shafts of the motors are directly coupled to the worm-shafts of the
hoisting mechanism. In the right-hand driving mechanism is a worm-shaft 4
which carries a left-hand worm 5 and a right-hand worm 6. In the left-hand
driving mechanism is a worm-shaft 7 which carries a right-hand worm 8 and a
left-hand worm 9. The left-hand worm of the right-hand driving mechanism is
opposite the right-hand worm of the left-hand driving mechanism, and the other
worms are likewise opposite to each other and of opposite hand. The worms
engage with worm-wheels which are mounted on two parallel worm-wheel shafts,
one of which is the drum shaft 10, and the other of which is the gear shaft 11.
The shafts are common to both driving mechanisms and are geared together by
two pairs of spur-gears 12, so that they will run synchronously.
The power from each motor divides equally between the two, worms on the
worm-shaft coupled to its armature shaft, and half the power reaches the drum
through the worm-wheel on the drum-shaft, and the other half of the power is
transmitted to the worm-wheel on the gear-shaft and from thence through the
train of two spur-gears to the drum-shaft.
The right-hand and the left-hand driving mechanisms are positively connected
by both the drum shaft and gear-shaft, and in each driving mechanism these are
positively geared together. In consequence of this duplication of the pairs of
spur-gears, the power from each motor will pass to the drum through the gearing
of both driving mechanisms, and the omission or failure of either pair of inter-
meshing spur-gears would still leave both worm-wheels of both driving-mechan-
isms positively geared to the drum. The motors being positively geared to the
drum, are, in consequence, positively geared to each other, and will invariably
run at identical speeds.
The worm-wheels are cut right or left-hand, according as they are to engage
with the right or left-hand worms. On the drum-shaft, the worm-wheel 13 is
left-hand to engage with the left-hand worm 5, and the worm-wheel 14 is right-
hand to engage with the right-hand worm 8. On the gear-shaft the worm-
wheels are also of opposite hand, the worm-wheel 15 being right-hand, and the
worm-wheel 16 being left-hand. The teeth of these wheels, which are on the
same shaft, consequently incline in opposite directions, as shown in Figure 2.

page_text: Since the two worms on each worm-shaft are of opposite hand, their end-thrusts
will be in opposite directions, and since they are geared to give the same ratio
of speed: between the worm-shaft and the drum, the end-thrusts of the worms
are completely balanced, and no thrust-bearings are necessary on the worm-
shafts. Likewise the end-thrusts in the direction of the length of the worm"
wheel shafts arising from the obliquity of the teeth of the worm-wheels are also
balanced, because the teeth of the two wheels on each shaft are inclined in opposite
directions. Since the corresponding worms and worm-wheels of the two driving-
mechanisms are of opposite hand, the motors must drive the worm-shafts in
contrary directions..
With the worm-wheels duplicated as described, it is necessary to so mount some
or all the gears that they can be adjusted with respect to their shafts such slight
amount as may be necessary to bring the teeth of the several gears into proper
mesh. In order to do this, the worm-wheels and spur-gears are not directly keyed
fast to their shafts, but are made in the form of rings, and bolted to flanges 17,
which are keyed to the shafts. Each flange serves as a support for both a worm-
wheel and the adjoining spur-gear. The bolts 19 pass through holes in the
flanges, spur-gears, and worm-wheels. The bolt-holes through some or
all of the worm-wheel rings and spur-gear rings are elongated, SO
that the rings may be slipped around such slight amount as may be necessary
for the proper intermeshing of the spur-gears, worm-wheels and worms. After
the rings have been adjusted, the bolts are screwed up tight.
The armatures A, A of the two motors by which this mechanism is driven, are
connected in series to the leads L, L, and the fields are in shunt with the
armatures. Motors with their armatures in series are difficult to maintain at
equal speeds, since inequality of field strength will cause the armature of the
motor with the stronger field to respond more quickly, and consume the greater
part of the electrical energy in the circuit, so that sufficient drop of potential
will not be left across the other armature to set it in motion. With the motors'
positively geared to each other, they cannot thus become unbalanced. In practice;
the circuits through the armatures and fields are led through suitable control:
apparatus, not shown or claimed in this application, but which has been made the:
subject of an application filed by the communicator on the 23rd of February,
1898, No. 4,549.
On each worm-shaft is a brake-wheel 20, and adjoining each brake-wheel is a
pair of brake-levers 21, which carry suitable brake-shoes 22. The brake-levers.
are fulcrumed to standards 23, which are bolted to the bed-plate of the machine.
Near the opposite ends of each pair of levers are holes through which a brake-
applying rod 24 is loosely passed. A head 25 at the lower end of the rod bears
against the lower brake-lever, and a washer 26 bears against the upper brake-.
lever. The head of the rod and the washer are each so shaped in conjunction
with the brake-lever, against which it bears, that each can rock slightly. A
brake-applying spring 27 lies between the washer against the upper brake-lever,
and a washer which lies under nuts at the upper end of the brake-applying rod.
The spring, which is compressed between the two washers, draws the ends of
the brake levers together and applies the brake shoes to the brake-wheel.
Toggles 28 are attached to the ends of the brake-levers, and these when straight-
ened separate the brake-levers and hold off the brake-shoes. The movement of
the lower brake-lever is limited by the contact of the head of the brake-applying:
rod with the bed-plate of the machine, and this movement is only half the
spreading action of the toggles, so that the spreading action will also operate
the upper brake-lever. But for this contact, only the lower brake-lever would
operate, since the weight of the upper brake-lever would keep its brake-shoe
always in contact with the brake-wheel. The links of each set of toggles are:
connected to a soft-iron plunger 29, and the two plungers operate in opposite:
ends of the solenoid 30. This solenoid when energized attracts both plungers.
and simultaneously releases the brakes from both worm-shafts. When the circuit-

page_text: through the coil is broken, the attraction of the plungers ceases, and the springs
simultaneously apply the brakes to both worm-shafts."
A slack-cable safety-device operating in conjunction with the hoisting cables
is carried by brackets 31 on the top of the machine. To a rock-shaft 32,
journaled in these brackets, weighted levers 33 and arms 34 are attached. The
ends of the arms carry the ends of the shaft 35, on which flanged idler wheels 36
are loosely mounted. By reason of the weighted levers tending to rock the rock-
shaft, these idler wheels are constantly pressed against the hoisting-cables, and in
event of these cables becoming slack, will press them outward and allow the rock-
shaft to rock. A guard-bar 37 is also supported by the arms, and lies in front
of the idler wheels and prevents the cables from leaving the grooves in the
wheels. Attached to a bar, between the brackets which carry the slack-cable
device, is a plate 38 with a bracket 39, which supports an electric switch-arm 40
and contact pieces 41. Attached to the rock-shaft is a sleeve 42 with a lug 43,
which contacts with the switch" arm when the rock-shaft is rocked, and throws
open the switch. The switch-arm is so hinged, that it will fall open by gravity
sufficiently to break any arc, after it has been pushed open sufficiently to clear
the contacts:
:
A cable-climbing safety-device is also provided; which operates in conjunction
with the drum, in event of any of the cables climbing out of their grooves in
which it is intended that they should wind, and either lying across the ridges
between the grooves, or on top of other convolutions of cables on the drum: This
device is a bar 44, which lies parallel with and close to the face of the drum, so
that the space between the cables and the bar will be considerably. less than the
height of the ridges on the drum, or the thickness of the cables. In event of
the cables climbing out of their grooves, the bar is forced back. It is supported
by short arms 45 on the ends of a short rock-shaft 46, which is journaled 'in
brackets on the top of the stand which carries the brake-solenoid. An arm 47 on
this rock-shaft is connected through a connecting rod 48 with a loose sleeve 49
on the rock-shaft of the slack-cable safety-device. Wherever the bar of the
cable-climbing safety-device is pushed away from the drum by the climbing of
any of the cables, the loose sleeve is rocked and its lug 50 contacts with the switch-
arm, above described, and opens the switch. The same switch-arm serves for
both the slack-cable and the cable-climbing safety-devices. The switch is con-
nected either directly or through relays with the circuits through the armatures
of the motors and the brake-solenoid.
Two sets of cables are shown in connection with the hoisting machine, each
consisting of four ropes, two of which lie adjacent in right-hand spiral grooves,
and two adjacent in left-hand spiral grooves upon the drum. The ends of the
cables in one of these sets, 51; are anchored adjacent to the flanges of the drum,
and, as shown, lead directly up from the drum, and are intended to lead to
the car. The ends of the cables in the other set, 52, are anchored to the drum
near its middle plane and are intended to lead to the counter-weight.
ft
In order that the cables may be carried horizontally from the hoisting machine
to the point where they may rise in the well, either for the car or a counterweight,
it is necessary to provide idler sheaves 53. To avoid leading the cables to the
idler sheaves obliquely, these sheaves must be mounted so that they shall be
carried laterally as the cables wind or unwind from the drum. To do this, there'
is provided a threaded shaft 54 which is positively driven from the hoisting
machinery through the bevel gears 55, shaft 56, and bevel gears 57. The threaded
shaft engages two nuts 58, which are held against rotation by the arms 59 engag-
ing with a guide-rail 60. These nuts serve as bearings for the idler sheaves.
As shown, the shaft is provided with a right-hand and a left-hand thread, it being
intended to carry two sheaves engaging with cables which unwind from right-
hand and left-hand grooves on the drum. The parts which carry the idler
sheaves are mounted on a separate base from the hoisting machine, and will
usually be at a greater distance than shown. The two pairs of bevel gears may

page_text: therefore be at considerable distance from each other, and the connecting shaft 56
will consequently have to be of such length as may be required.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. In a hoisting mechanism, the combination with a hoisting drum, of two
gear trains connected therewith, positive connections between the driving gears
of the gear trains, and independent driving mechanism for driving each of the
driving gears, substantially as described.
2. In a hoisting mechanism, the combination of two worm-wheel shafts, two
worm-wheels mounted on each worm-wheel shaft, two worm-shafts, two worms
on each worm-shaft in engagement with the worm-wheels, the two worms on each
worm-shaft being of opposite hand, and the two worm-wheels on each worm-
wheel shaft being of opposite hand, and means for driving the worm-shaft,
substantially as described.
3. In a hoisting mechanism, the combination of a winding drum, a worm-shaft
with two worms carried thereby, two worm-wheel shafts, a flange attached to each
shaft, a spur-gear ring and a worm-wheel ring bolted to each flange, the bolt-
holes in one of said rings on one of the flanges being elongated to admit of
circumferential adjustment, the spur-gears intermeshing and the worm-wheels
engaging with the worms on the worm-shaft, substantially as described.
4. In an electrically driven mechanism, the combination with leads supplying
current, of two sets of positive driving gearing, electric motors connected to
each set of gearing, and series connections between the armatures of the motors
and the leads, substantially as described.
5. In an electrically driven mechanism, the combination with leads supplying
current, two sets of positive driving gearing, electric motors connected to each
set of gearing, and series connections between the armatures of the motors and
leads, and shunt connections for the fields of the motors, substantially as described.
6. In a hoisting mechanism, the combination of two driving shafts, brake-
wheels on each driving-shaft, two brake-levers for each brake-wheel, each pair
of brake-levers being connected with a brake-applying rod and brake-applying
springs to draw them together, and toggles to separate them, a solenoid, and
plungers operating in opposite ends of the solenoid and connected to the toggles,
substantially as described.
7. In a hoisting mechanism, the combination with a winding drum and cables
thereon, of a cable-climbing safety device consisting of a bar parallel with the
face of the drum and distant from the cables on the drum by an amount less
than the depth of the grooves on the drum' or the thickness of the cables, and
means connected with the bar to effect the stoppage of the hoisting mechanism
on the bar being moved away from the face of the drum, substantially as described.
8. In a hoisting mechanism, the combination of an electric switch, a slack-
cable safety-device, and a cable-climbing safety-device, both of which devices are
operatively connected with the switch, substantially as described.
Dated the 30th day of Santambor 1898
HENRY H. LEIGH, C.P.A.,
No. 22, Southampton Buildings, Chancery Lane, London, W.C.