Improvements in Brushes for the Commutators of Electric Dynamos and Motors.
Year: 1897

page_text: Date of Application, 20th Mar., 1897-Accepted, 15th May, 1897
COMPLETE SPECIFICATION.
Improvements in Brushes for the Commutators of Electric
Dynamos and Motors.
I, EDWARD LIONEL JOSEPH, of 92, Queen Victoria Street, in the City of London,
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, and accompanying drawing, that is to say:-
My invention relates to the metallic brushes ordinarily used for the commutators
of electric dynamos and motors.
Such brushes are ordinarily made of a sufficient number of thicknesses of wire
gauze of copper or other suitable metal, bound together so as to form a flat
rectangular bar of sufficient flexibility and elasticity of the required size to fit freely
and be clamped in an adjustable socket connected with one of the conducting wires
of the circuit, the outer end of the compound bar or brush pressing with sufficient
force upon the surface of the revolving commutator which is situated at a short
distance from the socket which carries the brush to allow the required elasticity in
the latter.
As the wearing end of the brush wears away, the compound bar is from time to
time fed forward in the socket to compensate for such wear, and when the whole of
the bar has been so fed forward a fresh one is inserted, the old one being rejected as
no longer of use, the part then remaining between the socket and the worn end
being therefore wasted.
My invention has for its object a method of construction by which such part is not
wasted, a fresh compound bar or brush being added and attached to the end of the
former one, so that the latter can be further fed forward until it has been nearly all
worn away by use.
The accompanying drawing is in illustration of my invention. I form at the
upper end of the brush a, Figure 1, a tongue b of copper or other suitable metal,
preferably of similar shape and cross section to the brush a but of less dimensions,
which tongue may be made by removing the outer part of the brush for a sufficient
distance down, and upon the lower end of the supplementary brush, c Figure 2, which
is to be added to the upper end of the principal one a when necessary as above
explained, is fitted a hollow socket d of copper or other suitable metal the outer
shape and dimensions of which correspond exactly in cross section with the outer
shape and dimensions of the compound bar a which forms the brush, whilst the
opening through it fits upon the projecting tongue 6 upon the upper end of the
brush a already described. The socket d is brazed upon a tongue e which enters it
for a sufficient distance and is formed upon the lower end of the supplementary bar
or brush c, and the lower end of the socket d is soldered upon the tongue at the
upper end of the original brush a so as to form perfect metallic contact with
the same.
By this method of construction the original brush a can be fed forward to the
commutator until it has been nearly entirely worn away, and the remaining end can
then be unsoldered from the socket d upon the upper bar c, and a fresh brush can
then be inserted in the socket and fed forward until it becomes necessary again to
apply and solder its upper end into the socket d upon the upper bar as described.
By this means great economy of material is effected nearly the whole of the copper
or other brushes being used up.

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:
1. In brushes for the commutators of electric dynamos and motors, the method of
adding to the upper end of the brush when worn, a supplementary brush temporarily
fixed in electrical contact with the latter, substantially as and for the purpose
described and illustrated.
2. For the purpose described in the first claim, the combination with the brush a,
of the tongue b at its upper end, the supplementary brush c, having a tongue e at its
lower end, and the socket d by which the brushes a and c and connected in electrical
contact, substantially as described and illustrated.
Dated this 18th day of March 1807
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.