Improvements in Brushes and Brush Holders for Electric Machines.
Year: 1891

page_text: Date of Application, 25th Feb., 1891
Complete Specification Left, 23rd Nov., 1891-Accepted, 2nd Jan.,
1892
PROVISIONAL SPECIFICATION.
Improvements in Brushes and Brush Holders for Electric Machines.
HERBERT JOHN DOWSING 4 Queen Victoria Street London, E.C. Electrical
Engineer do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in brushes and brush holders in dynamo
machines and has for its object, the prevention of waste in connection with the
brushes used.
In order to obtain my object I dispense entirely with the upper part of the brush
as usually made, which serves simply as a conductor and support for the lower, or
wearing part of the brush, and which collects the current from the commutator.
In one form of my invention I make a separate handle or clip, consisting of a
plate, or plates of suitable material of such form that it will fit and move up and
down in the ordinary brush holder attached to the machine. At the lower end
of this holder I form a clip of a suitable form with arrangements for holding firmly
and making good contact with one end of the wearing brush. By this means the
part that wears can be removed when necessary, and easily replaced.
In another form of my invention, I use a hollow form of holder or clip made
as in the other case to fit into the ordinary brush holders attached to the machine.
Through this hollow holder or clip I pass a longer wearing brush than can be used
in the ordinary form, and which can be adjusted by set screws, clamp, or other
suitable means. When the part nearest the commutator is worn, the wearing brush
can be re-adjusted as desired.
My invention can be adapted to all forms of dynamo machines using brushes,
and also to electro motors, and all kinds of electric machines where current is
required to be collected from a moving surface, such as a commutator.
Kobruary 25th 1801
H. J. DOWSING.
COMPLETE SPECIFICATION.
Improvements in Brushes and Brush Holders for Electric Machines.
1, HERBERT JOHN DOWSING, of 4 Queen Victoria Street, in the City of
London, Electrical Engineer, do hereby declare the nature of the said invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement, that is to say :-
My invention relates to improvements in brushes and brush-holders for dynamo
and other electric machines, and has for its object the prevention of more or less
of the waste of material that occurs in connection with certain kinds of such
brushes as at present constructed and used.
One form of brush at present in use in dynamo and other electric machines is
composed of a number of plates of copper soldered together flatwise, one over the
other, at their rear ends so as to form a comparatively thick solid plate which
serves as a conductor or collector of current and as a holder or carrier for the
wearing part of the brush which is composed of the front ends of the aforesaid
plates which are not soldered together, but are left free to bear at their front
ends against the surface of the commutator. The rear end of the brush which
forms the aforesaid holder or carrier, is adapted to fit into and to be adjusted and
secured in the brush-holder attached to the dynamo, or other electric machine.
Another form of brush at present in use, consists of a piece of copper adapted to
[Price 8dl

page_text: fit into and to be adjusted and secured in the brush-holder attached to the dynamo
or other electric machine. On to the front end of this piece of copper is soldered
or otherwise permanently secured, a sheet of wire gauze folded up so as to form a
prismatic bar, the front end of which bears against the surface of the commutator.
In these and other similar forms of brush when the front or wearing part has
worn down to within a certain distance, in the one case, of the hinder part of the
plates where they are soldered together, and in the other case of the aforesaid
piece of copper, the whole of the remaining material, that is to say, both the front
or wearing part and the part behind it forming the holder or carrier, which fits
into the brush-holder of the dynamo or other electric machine, are useless and
have to be removed from the said machine and new entire brushes supplied in
place thereof.
Now according to my present invention I dispense with the hinder part of the
brush as usually made, and substitute therefor a separate holder or carrier adapted
to fit into and to be adjusted and secured in the brush-holder of the dynamo or
other electric machine, and provided with means for clamping or holding a separate
and distinct piece of material composing the wearing part of the brush.
When
one of these wearing parts has worn down to so short a length as to be of no
further use, it is removed from the aforesaid separate holder or carrier, and a
fresh wearing part is inserted and clamped therein, so that the only material
wasted is the aforesaid short length of the wearing part, the holder or carrier
remaining available to receive an indefinite number of successive wearing parts.
And in order that my said invention may be fully understood, I will now proceed
to describe the same with the aid of the accompanying drawing which is an
isometrical projection of a brush and brush-holder constructed in accordance with
my invention.
A is a separate holder, carrier, or handle, composed of suitable material such as
brass or gunmetal for example, adapted to fit and slide to and fro, or up and
down, and to be secured in any desired position in the ordinary brush-holder
attached to the dynamo or other electric machine. This holder may be cast metal
as indicated in full lines, or it may be made from a plate of metal bent to shape
as indicated in dotted lines in the figure. At the front end of this holder or
carrier is formed a clamp, or clip, composed of two jaws A' A', between which is
placed one end of a separate and removable wearing piece B formed of a folded
sheet of wire gauze, several plates of copper placed one over the other, a prisinatic
piece of carbon, or any other suitable material. The wearing piece B may be
secured between the jaws A' A¹ of the holder or carrier A, by means of screws
passing through the two jaws and the wearing piece B, or by any other suitable
mechanical means that will secure good electrical contact between the parts, and
will enable the wearing piece B to be easily placed and secured in the holder A,
or removed therefrom. C is a backing piece to support the wearing piece B, and
to keep its front end pressed against the surface of the commutator.
It may be
moved backwards from time to time as the wearing piece B wears away, and may
be secured in any desired position by means of the nuts D on the screwed studs E,
which pass through the slots F in the backing piece C and are secured in the
upper jaw A. Or if preferred, instead of the screwed studs E E secured in the
upper jaw A', screw bolts may be employed which pass through both jaws A¹ A',
the wearing piece B, and the backing piece C, such screw bolts being provided
with suitable heads which may be formed with square stems, or be provided with
other suitable means to prevent the bolts from turning when the nuts D D are
turned for the purposes of clamping or unclamping the parts.
By these means the part of the brush that wears away can easily be replaced
without wasting the part that forms the holder or carrier of the said wearing
part.
This invention can be readily adapted to suit any form of dynamo or other
electric machine, or motor, in which brushes are used to collect current from a
moving surface such as a commutator for example.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A brush and brush-holder for dynamo and other electric machines, consisting
of two separate parts, namely a holder, or carrier, adjustable in the brush-holder
of the dynamo, or other electric machine, and a wearing part connected to the
said adjustable holder or carrier by screws, or other suitable mechanical devices,
in such manner that the said wearing part can be readily secured to, or removed
from, the said adjustable holder or carrier at pleasure, substantially as hereinbefore
described, and illustrated in the drawings.
Dated this 20th day of November 1891
H. J. DOWSING,
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent.
H. J. DOWSING,
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent.