Improvements in Control Apparatus for Electric Hoists and Elevators.
Year: 1899

page_text: Date of Application, 7th Mar., 1899-Accepted, 22nd Apr., 1899
1
COMPLETE SPECIFICATION.
Improvements in Control Apparatus for Electric Hoists and Elevators.
I, OLIVER IMRAY, of. Birkbeck Bank Chambers, Southampton Buildings, in
the County of London, Chartered Patent Agent, do hereby declare the nature of
this invention (as communicated to me from abroad by Andrew Ellicot Maccoun,
of Braddock, in the County of Allegheny and State of Pennsylvania, United States
of America, Electrical Engineer) and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-.
My invention relates to means for automatically slowing down the car of an
electric hoist or elevator near each end of its travel; of controlling its movements,
and of stopping the car or cage always at exactly the same point whatever be its
load, as I shall describe with reference to the accompanying drawings. :
Fig. 1 is a diagrammatic view of the whole arrangement, Fig. 2 is a part plan
of the connections between, the hoisting shaft and the cut-out switch, and Fig
is a part end view of the same. In Fig. 1, 2 is an electric motor of known kind;
it is shewn as a compound motor with the shunt field 3 connected by the con-
ductors 5 and 6 from the dynamo to opposite sides of a two pole switch 4. 7 is
an ordinary reversing controller having an operating handle S and suitably con-
nected to the dynamo and the switch 4 as indicated. 9 is a cut-out switch
preferably rotary, actuated by the handle 10 and link 11 by this, connection may
be made for current to the hoist; and the switch is automatically opened by a
lever 12, (Figs. 2 and 3) loose on a shaft 13 and connected by a link 14 with
the drum of the cut-out switch. A loose uut 15 upon this shaft is held against
rotation by a lug 16 and the shaft is geared to the hoisting drum, the arrangement,
being such that when the car or cage reaches the limit of its travel the screw
engages and actuates the lever so as to swing the drum and break the motor
circuit.
.R
In order to slow down the car before it reaches the end of its travel, I provide
suitable resistance 17 connected to bars over which travel spring fingers 18 upon
the link 19 The fingers are moved over the resistance by means of 'a cam 20
acting upon a pin on a lever 21, which is connected by a link 22 bell crank 23
jointed to 19..
The cam shaft is geared to the hoisting drum and is so arranged that when
the circuit is closed and the hoist started, the lever drops, thus moving the spring,
fingers along the résistance and speeding the motor, but when the hoist nears
the end of its travel the lever is again raised introducing resistances so as to
slow down the motor before the car reaches the end. The slowing down device is
described as applied to hoists in which the car is stopped automatically only at
the top and bottom. When it is desired to stop the car at intermediate points
as in elevators the automatic slow-down device may be arranged, if. désired, to
operate, at each intermediate point by using a series of notches, in the cam
groove, so that the pin of the lever 21 would rise and fall at the points corre-
sponding to the different heights. The hoist can be stopped at any point by
using the hand controller.

page_text: With the arrangement thus far described, the motor would stop the car before
reaching the desired point if a heavy load were carried. In order to overcome this
difficulty I provide a switch 24 having the lever 25 of its drum connected by a
link 26 to the armature 27 of an electromagnet 28 and to an adjustable spring 29.
The magnet and switch being connected up as shewn, when the controller 7 is
thrown on, the electromagnet 28, which is in series with the main current of the
motor 2, lifts the armature and causes the switch 24 to short circuit part of the
slow-down resistance at the starting and thus cause the motor to start more
quickly, as it cuts out part of the resistance before the spring fingers are moved
to do the same.
The armature remains lifted and the switch 24 closed until the motor begins
to slow down, when the car nears the end of its travel, and as the current is then
reduced through the electro-magnet the armature drops and the spring 29 opens
the switch 24. This spring is adjusted so that the armature is released when a
light or medium load is being carried, and thus resistance is introduced to slow
down the motor, but when a heavy load is being carried the current is sufficient
to hold up the armature and keep the switch 25 closed until the car reaches nearly
the end of its travel; thus part of the resistance is cut out and the motor is
slightly increased in speed. By adjusting the spring the parts can be arranged
so that the motor will always stop the car or cage at exactly the same point
notwithstanding difference of loads.
: The circuit is as follows: From positive terminal of switch 4 by 31 to a
plate 37 when the controller is thrown on, the insulated metal ends 34 and 35
on the arm 86 make the connection from 37 to 39 and from 3S to 50, thus driving
the hoist-motor in one direction. When the handle is thrown in the opposite
direction, connection is made. from 14 to 37 and from 38 to 45 reversing the
current through the armature and driving the hoist in the other direction. When
it runs in the direction first described, the current flows by 31 to 37 and by
34 to 39, from 39 through resistance 51 back to 47 from 47 to 30, from 30 through
the armature back to 383, thence to 48, from 48 through resistance 52 to 38, from
38 to 2 through 17 to 18, through 9 and then through magnets 28 and thence
to the negative terminal of the switch. When a controller is all thrown on
the resistances 51 and 52 are cut out as the arm passes over the segments.
By my invention the hoist is put under complete control; the car or cage
slows down near the end of its travel, and the motor always stops the car at the
same point irrespective of the load being carried. The cut-out switch and con-
troller are operated by hand to start the car or cage from either end of its travel,
but the slowing down and stopping are automatically effected.
"Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is;-
1. In combination with an electric elevator or hoist, mechanism actuated by
the movement of the hoist and arranged to automatically introduce resistance so
as to slow down the motor as the car nears the end of its travel; substantially as
described.
:
2: In an electric hoist controller a series of resistance blocks in the motor
circuit, and a contact surface moved over the blocks by connections with the
hoisting drum, substantially as and for the purpose set forth.
3. In combination with the hand worked cut-out switch a mechanism con-
necting it with the hoist drum and arranged to automatically break the main
current when the car reaches the limit of its travel, substantially as described.
4. The combination of the electro-magnet and its armature, a switch and an
adjustable spring arranged and operating, substantially as and for the purpose
set forth:
5. The combination of a reversing controller and a hand worked cut out switch
included in the circuit, connections to the cut out switch from the hoisting drum
arranged to break the main current when the car reaches the end of its travel,

page_text: mechanism arranged to cut in a slow down resistance as the car nears the end of
its travel, and another switch arranged in connection with the resistance and
actuated by an electromagnet in series with the current through the main motor,
substantially as described.
T
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6 Г
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1000
ABEL & IMRAY,
Agents for the Applicant.