IMPROVEMENTS IN THE TRANSMISSION OF POWER BY ELECTRICITY AND IN THE APPARATUS EMPLOYED THEREIN
Year: 1879

page_text: LETTERS PATENT to John Hopkinson, of Westminster Chambers, in the City
of Westminster, for the Invention of "IMPROVEMENTS IN THE TRANSMISSION
OF POWER BY ELECTRICITY AND IN THE APPARATUS EMPLOYED THEREIN."
Sealed the 13th February 1880, and dated the 14th November 1879.
PROVISIONAL SPECIFICATION left by the said John Hopkinson at the Office
of the Commissioners of Patents on the 14th November 1879.
JOHN HOPKINSON, of Westminster Chambers, in the City of Westminster.
"IMPROVEMENTS IN THE TRANSMISSION OF POWER BY ELECTRICITY AND IN THE
APPARATUS EMPLOYED THEREIN.'
"
My Invention relates to a method of reversing the direction of rotation of the
armature of dynamo-electric or magneto-electric machines when the said machines
are used for converting an electric current into mechanical power, and it consists
in effecting such reversal by changing the position of the points of contact of the
brushes or their equivalents with the commutator or collector of the said
machines.
According to one mode of carrying out my Invention I employ two pairs of
copper brushes or equivalent devices mounted respectively on two pins insulated
from the frame and from each other, and situate one on each side of the axis of the
armature, the pins being connected together by a link or otherwise, so that they
can be turned simultaneously in the same direction. By the act of turning the
two pins in one direction one of the brushes or equivalent devices carried by each
pin is brought into contact with the commutator, the points of contact being
opposite to each other and appropriate to one direction of rotation, and by the act
of turning the two pins in the opposite direction the other brush or equivalent
device carried by each pin is brought into contact with the commutator, the points
of contact being appropriate to the opposite direction of rotation.
According to another mode of carrying out my Invention I mount only a single
brush or equivalent device upon each pin, and produce the same result as that
herein before indicated by turning the two pins through a greater angle so as to
bring opposite faces of the brushes or equivalent devices into contact with the

page_text: commutator, according to the direction in which it is required that the armature
shall revolve. Or the brushes or equivalent devices may be caused to change the
points of contact with the commutator for the purpose of effecting a reversal of the
direction of rotation of the armature by sliding the said brushes or equivalent
devices round the commutator in lieu of rotating them about an axis. In this case
the brushes or equivalent devices may be carried by a cross piece (from which
they are insulated) moveable about the same axis as the armature, and the
electrical connections are by preference made by means of spring contact pieces
arranged in relation to fixed metal pieces so as to be connected with either the
positive or negative source of electricity only when the brushes or equivalent
devices are in or near their correct position.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Hopkinson in the Great Seal Patent Office on the 7th May
1880.
JOHN HOPKINSON, of Westminster Chambers, in the City of Westminster.
"IMPROVEMENTS IN THE TRANSMISSION OF POWER BY ELECTRICITY AND IN THE
APPARATUS EMPLOYED THEREIN."
My said Invention relates to means of reversing the direction of rotation of the
armature of dynamo-electric or magneto electric machines when the said machines
are used for converting an electric current into mechanical power, and it has
reference to improvements upon an Invention in respect of which former Letters
Patent were granted to me, dated the Twenty first June, One thousand eight
hundred and seventy nine, No. 2481.
According to my said former Invention I effected the reversal of the direction of
motion of the armature of the machine by changing the position of the points of
contact of the brushes or equivalent devices and commutator or collector. Now
my present Invention consists chiefly of improved methods of charging the points
of contact on the commutator or collector of the brushes or equivalent devices for
the purpose of effecting such reversal of the direction of motion of the armature of
the said machines.
In carrying out my present Invention I employ a single pair of copper brushes or
equivalent devices to admit the current to and conduct it from the commutator or
collector of the armature, these brushes or equivalent devices being arranged in the
following manner, videlicet :—
On opposite sides of the axis of the armature are two pins which are insulated
from the frame of the machine and from each other, and are coupled together by
means of a link or any other suitable connection so as to admit of their being
turned simultaneously in the same direction; each pin carries a single collecting
brush or equivalent device so arranged that when one face of each brush or
equivalent device is in contact with the commutator or collector the armature will

page_text: be caused to revolve in one direction, and that when the opposite face of each
brush is in contact with the commutator or collector the armature will be caused to
revolve in the opposite direction. By the act, therefore, of turning the pins in one
direction or the other through a sufficient angle so as to bring one face or the other
of each brush or equivalent device into contact with the commutator or collector
the motion of the armature in the required direction will be obtained.
Or in lieu of the preceding arrangement the brushes or equivalent devices may
bo caused to change the points of contact with the commutator for the purpose of
effecting a reversal of the direction of rotation of the armature by sliding the said
brushes or equivalent devices round the commutator or collector, instead of rotating
them about an axis. In this case the brushes or equivalent devices may be
carried by a cross piece (from which they are insulated) moveable about the same
axis as the armature, and the electrical connections are by preference made by
means of spring contact pieces arranged in relation to fixed metal pieces so as to
be connected with either the positive or negative source of electricity only when
the brushes or equivalent devices are in or near their correct position.
And in order that my said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figures 1 and 2 of my Drawings are diagrams of a commutator or collector with
my said Invention applied thereto, according to one modification of the same, the
brushes being shewn in different positions in the two Figures; Figures 3 and 4,
and Figures 5 and 6 are similar views to Figures 1 and 2, illustrating respectively
two other modifications of my said Invention.
Referring to Figures 1 and 2, A represents the commutator or collector of a
Siemens, Gramme, or other equivalent machine, when used as a motor, and a the
axis of the armature, the straight arrow through the centre indicating the direction
of the magnetic force of the fixed magnets, and the curved arrow denoting the
direction of motion of the armature. On opposite sides of the axis a are two
pins B, C, each of which carries a collecting brush, the brush carried by the pin B
for admitting the current being marked D, and the brush carried by the pin C for
receiving the current being marked E. The pins are insulated from the frame of
the machine and from each other, as before mentioned, and are coupled together by
a link or other suitable connection (not shewn in my Drawings) so as to enable
them to be turned simultaneously in the same direction. In Figure 1 the brushes
D, E, are represented with one of their faces in contact with the commutator or
collector, this position of the brushes being appropriate to the direction of rotation
of the armature indicated by the curved arrow in that Figure, whilst in Figure 2
the brushes are represented with their opposite faces in contact with the com-
mutator or collector, this position of the brushes being appropriate to the direction
of rotation of the armature indicated by the curved arrow in Figure 2, and which
is the opposite of that indicated in Figure 1. By the act, therefore, of turning
the pins B, C, simultaneously a reversal of the direction of motion of the
armature is obtained.
According to other modifications of the Invention, which are illustrated in
Figures 3 and 4, and Figures 5 and 6, the brushes D, E, are caused to change the
points of contact with the commutator or collector A for the purpose of effecting
the reversal of the direction of the rotation of the armature by sliding the said
brushes round the commutator. In the example shewn in Figures 3 and 4 the
brushes are slid round in one direction, whilst in the example given in Figures 5
and 6 the brushes are slid round in the opposite direction, the same effect, videlicet,
the reversal of the direction of rotation of the armature, being obtained. For this
purpose the brushes D, E, are carried by, but insulated from a cross piece F (shewn
in dotted lines), which is moveable about the same axis a as that of the armature,
so that by the act of operating the said cross piece the brushes may be moved from

page_text: the positions shewn in Figures 3 and 5 to the positions indicated in Figures 4 and 6,
or vice versa, according to the direction of motion required.
It is preferred to break the circuit during the passage of the brushes from one
position to the other by the employment of spring contact pieces G, H, connected
respectively with the brushes D, E, in combination with fixed metal pieces I, K,
and I, K, connected with sources of electricity of an opposite denomination, with
which metal pieces the brushes make contact only when the former are in or near
the correct positions.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
First. The method of changing the points of contact on the commutator or
collector of the brushes or equivalent devices, for the purpose of reversing the
direction of rotation of the armature or revolving portion of the machine, by
carrying such brushes or equivalent devices upon pins moveable about separate
axes in such a manner that opposite faces of the brushes or equivalent devices may
be brought into contact with the commutator or collector, substantially as herein-
before described.
Second. The method of changing the points of contact of the brushes or
equivalent devices, and commutator or collector, for the purpose of reversing the
direction of rotation of the armature or revolving portion of the machine by sliding
such brushes or equivelent devices round the commutator or collector, substantially.
as herein before described.
Third. In combination with the subject matter of the second claiming clause, the
mode of breaking the electric circuit when the brushes or equivalent devices are
in any other but an appropriate position, substantially as hereinbefore described.
In witness whereof, I, the said John Hopkinson, have to this my Specification
set my hand and seal, the Twenty eighth day of April, One thousand
eight hundred and eighty.