Improvements in or connected with Switches for Controlling Electro-motors.
Year: 1890

page_text: Date of Application, 8th Feb., 1890
Complete Specification Left, 10th Nov., 1890-Accepted, 7th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in or connected with Switches for Controlling
Electro-motors.
We, CHARLES THOMAS WHITMORE, of No. 61, Lawford Road, Kentish Town,
in the County of Middlesex, Gentleman, and WILLIAM HOPKIN AKESTER, of
No. 15, Munster Road, Walham Green, in the County of Middlesex, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in or connected with switches to be
employed for the purpose of controlling electro-motors, by means of which, the
desired object, such as the reduction, or increase of the speed or power, and the
reversal of the direction of rotation can be effected in a simple and efficacious
manner.
The switch consists of a compound contact bar, the construction of which is
hereinafter described, and a number of contact plates mounted upon a suitable base,
which latter is formed of non-conducting material, or is so insulated, that no
electrical connection exists between it and the said contact bar and contact
plates.
The field magnet circuit, in which are the accumulators or other source of
electricity, has its course constant, that is to say, whenever the circuit is completed,.
the current will always flow through the magnet coils in the same direction. One
pole of the said circuit is in electrical contact with a metallic plate or boss in the
centre of the before mentioned base, and the contact bar is mounted on a pin
projecting from the said metallic plate in such a manner as to admit of the partial
revolution of the said bar, and the inner plate of the said contact bar bears against
the face of the said metallic plate or boss, and is in constant electrical contact
therewith, whilst the outer plate of the contact bar is insulated from the said
metallic plate or boss. The opposite pole of the circuit is connected to a contact
plate so arranged, that whatever may be the position of the contact bar, the outer
plate of the latter is always in electrical contact with the said contact plate.
The various contact plates of the switch are so arranged on the base, and are so
coupled up with the armatures, that by changing the position of the contact bar,
the current may be caused to flow in either direction through the armatures in
multiple, or through one armature only, or through the armatures in series, or the
circuit may be broken.
For the above purpose, it will be found convenient to so arrange the contact plates,
that the contact bar, when put right over to one side, will make contact with such
contact plates as will complete the circuit through the armatures in multiple, whereby
the motor is caused to travel at its greatest speed, or to exert its greatest force. By
moving the contact bar round on its pivot nearer to its central position, the contact
thereof with the contact plates lastly referred to, will be broken, and contact will
be made with fresh contact plates so connected, that the circuit completed will be
through one armature only, whereby the speed or force exerted by the motor will
be reduced; and by moving the contact bar still nearer to its central position, the
same is caused to make contact with plates so coupled with the armatures, that the
circuit completed will be through the armatures arranged in series, and the speed
or force of the motor is reduced to its lowest point. When the contact bar is
moved to its central position, all circuits are broken, and the motor is brought
to rest.
On moving the contact bar beyond its central position, the plates with which it
is thereby brought into contact to complete the circuit, are so coupled with the
armatures, that the current will flow through the latter in a direction opposite to

page_text: that taken by it when the circuit has been completed by the contact bar making
contact when at the other side of its central position, as herein before described;
consequently the direction of rotation of the motor will be reversed.
The first contact made by the contact bar on being moved beyond its central
position, will effect the completion of the circuit through the armatures in series,
the next contact will complete the circuit through one armature only, and the last
contact through the armatures in multiple.
When the circuit is completed, the direction of the current through the field
magnets is constantly the same in whatever position the contact bar may be, the
direction of the current through the armatures being alone reversed.
The contact bar hereinbefore referred to, is formed of two plates, which are
completely insulated from each other, the inner plate is in electrical contact with
the metallic plate or boss in the centre of the base, and with the pin projecting
therefrom, whilst the aperture in the upper plate through which the said pin passes,
is enlarged, so that there is no clectrical contact between the two, and a washer, of
suitable non-conducting material, is arranged between the device employed for
securing the contact bar in position on the pin and the outer plate. The said outer
plate of the contact bar is arranged to make contact with plates, the faces of which
are lower than those with which the inner plate makes contact, and for this purpose,
flanges, formed at the sides of the outer plate, are turned down so as to project
below the inner plate.. A small metallic plate is arranged on the under face of the
inner plate, but completely insulated therefrom, and from the outer plate, for effecting
the electrical connection necessary for working the armatures in series.
It will be readily understood by persons conversant with electro-motors, that
instead of using two armatures, a series of resistances may be substituted for one of
the armatures, and, when this is the case, in order to control the speed of, or force
exerted by the motor, the current is directed to flow through one or more of the
resistances as required, the resistances being coupled or electrically connected with
contact plates suitably arranged for that purpose.
Dated this 8th day of February 1890.
VAUGHAN & SON,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in or connected with Switches for Controlling
Electro-motors.
We, CHARLES THOMAS WHITMORE, of No. 61, Lawford Road, Kentish Town,
in the County of Middlesex, Gentleman, and WILLIAM HOPKIN AKESTER, of
No. 15, Munster Road, Walham Green, in the County of Middlesex, Electrical
Engineer, 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, reference being had to the drawings hereunto annexed, and
to the figures and letters marked thereon, that is to say :-
Our said invention relates to improvements in or connected with switches to be
employed for the purpose of controlling electro motors by means of which the desired
object, such as the reduction or increase of the speed or power, and the reversal of
the direction of rotation can be effected without reversing the polarity of the field
magnets, in a simple and effective manner.
In the drawings, Figure 1. is a diagram showing the connections between the
field magnets, the source of electricity, the contact plates, and the armatures;
Figure 2. is a plan of the switch-board; Figure 3. is a transverse section showing
the contact bar in the position indicated by the line 1.-1. of Figure 2.; and
Figure 4. is a similar view showing the contact bar in the position indicated by the
line 2. 2. of Figure 2.
a. represents the base plate of the instrument which is formed of non-conducting

page_text: naterial, or,
so insulated, that no electrical connection exists between it and the
contact bar and contact plates hereinafter more fully described.
b. b are the field magnets, the circuit of which is constant, that is to say, when-
ever the circuit is completed, the current will flow from the accumulators c. or
other source of electricity located in the same circuit through the magnet coils in
the one direction.
One pole of the said circuit is, by a conductor * permanently in electrical
connection with a metallic plate or boss d. located in the centre of the base plate a.,
whilst the other pole of the circuit is, by a conductor 61* permanently in electrical
connection with a metallic contact plate e. arranged in the arc of a circle concentric
with the boss d.
The contact bar f. is mounted with capability of revolution upon a central pin
or axis a fixed to the base a. and metallic boss d., and the inner plate f¹ of the
contact bar bears upon the face of the boss d. and is in constant electrical contact
therewith and with the pin or axis a', whilst the outer metallic plate 2 of the contact
bar f. at each end is formed to surround the metallic plate f¹ and is insulated there-
from and from the pin or axis a' and boss d. by any suitable insulating material f³.
The parts of the compound bar f. are firmly united by screws and nuts f₁ also
insulated by similar material f3 and the compound bar f. is held in place by a
nut a screwing upon the pin a¹ and insulated from the plate 2 by a non-conducting
washer f3*.
A small metallic plate f is arranged upon the under face of the inner plate f¹
but completely insulated therefrom and from the outer plate f2 by non-conducting
material f3 for effecting the electrical connection necessary for working the armatures
in series.
The plate e., to which one pole of the circuit is connected, is so arranged, that,
whatever may be the position of the contact bar f., the outer plate f² thereof by
its peculiarly formed end always in electrical contact with the contact plate e.
The various contact plates g. gl h. of the switch are so arranged upon the
base a.,
and are, by the usual connections, so coupled with the armatures i. i', that
by changing the position of the contact bar f., the current may be caused to flow in
either direction, through the armatures i. in multiple, or through one armature
only, or through the armatures in series, or the circuit may be broken.
In carrying out this system, it will be found convenient to arrange the contact
plates g. gh. h' in the manner indicated, so that the contact bar f. when moved
right over to one side, as indicated by the line 1.-1. of Figure 2., will make contact
with such contact plates as will complete the circuit through the armatures in
multiple, whereby the motor will be caused to travel at its greatest speed, or to
exert its greatest force.
By moving the contact bar round on its pivot a¹, nearer to its central position,
as indicated by the line 3.-3. Figure 2., the contact thereof with the contact
plates, lastly hereinbefore referred to, will be broken and contact will be made with
other contact plates so connected, that the circuit completed will be through
one armature only, whereby the speed or force exerted by the motor will be
5 reduced.
By moving the contact bar f. still nearer to its central position, as indicated by
the line 2. 2. of Figure 2., it will be caused to make contact with plates so
coupled with the armatures, that the circuit completed will be through the
armatures i. in series, and the speed or force of the motor will be reduced to its
0 lowest point.
When the contact bar f. is moved to its central position, which it is represented
as occupying in Figure 2., all circuits will be broken and the motor will be brought
to rest.
Upon moving the.contact bar f. beyond its central position in the same direction
5 of rotation, it will be brought into contact with plates so coupled with the
armatures i. i, that the current will flow through the latter in a direction opposite
to that taken by it when the circuit was completed by the contact bar f. before

page_text: passing its central position, as herein before described, and consequently, the direction
of rotation of the motor will be reversed.
The first contact made by the contact bar f. on being moved beyond its central
position, will effect the completion of the circuit through the armatures i. i¹ in series;
the next contact will complete the circuit through one armature only, and the last
contact in the same direction through the armatures in multiple.
In electric switches constructed in accordance with our invention, upon the
completion of the circuit, the current through the field magnets b. b', as already
pointed out, is constantly the same whatever may be the position of the contact bar,
the direction of the current through the armatures being alone reversed.
It will be readily understood by persons conversant with electro motors, that
instead of using two armatures i. i, a series of resistances may be substituted for
one of the armatures, and, in this case, in order to control the speed or force of the
motor, the current is directed to flow through one or more of the resistances, as
required, the resistances being coupled, or electrically connected, with contact plates,
suitably arranged for that purpose.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In an electric switch, the general combination and arrangement of parts,
whereby the direction of motion of the motor can be reversed without reversing the
polarity of the field magnets, substantially as herein shown and described.
2. In an electric switch, the peculiar construction of contact bar, herein shown
and described.
3. In an electric switch, arranging the contact plates and conductors in such
manner, that the contact bar can be placed in the field magnet circuit and complete
the circuit through one armature only, or through the two armatures in series, or in
multiple, substantially as herein shown and described.
Dated this 10th day of November 1890.
VAUGHAN & SON.,
Agents for the Applicants.