Commutator Brush Holders and Brushes for Electric Motors or Dynamo Electric Machines.
Year: 1898

page_text: Date of Application, 16th June, 1898-Accepted, 6th Aug., 1898
COMPLETE SPECIFICATION.
Commutator Brush Holders and Brushes for Electric Motors or
Dynamo Electric Machines.
We, EDWARD HIBBERD JOINSON, .Electrician, and ROBERT LUNDELL, Electrician,
both of No. 527 West 34th Street, in the County of New York, and State of New
York, United States of America, 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:-
This improvement has for its object, To produce a commutator brush holder
and brush or brushes therefor which shall avoid, as far as possible, the objec-
tionable features attributable to existing types of such devices and which shall
possess the following characteristics of utility.
1st. Freedom from noise, such as chattering or squeaking and the capacity of
permitting the commutator to be rotated in either direction with equally good
results under all conditions of usage.
2nd. Maximum current carrying capacity during the entire life of the brush
or brushes.
3rd. Freedom from heating usually attributable to loose contacts, frictional
joints or unequal wear of the brush bearing surfaces on the commutator as it is
fed forward.
4th. Freedom from the wearing of ridges on the commutator surface between
the ends of adjacent brushes.
5th. The utilization of maximum surface of the commutator in the direction of
the length of the strips thereof.
6th. Adjustability as to tension and surface wear.
7th. Adaptability to utilize at will either end of a novel commutator brush pro-
vided with a centrally located clamping slot or opening; and,
8th. To construct a brush holder in which the clamping parts are made as light
as possible, so as to prevent jumping of the carbon brushes held thereby in the
event of the machine itself being subjected to vibration, as for instance is the case
with railway motors.
The improvement will be fully understood by referring to the accompanying
drawings, in which,
Figure 1 is an end elevational view of a part of the commutator of an electric
motor or dynamo electric machine illustrating the novel brush holder and brush
therefor in side elevation.
Figure 2 is a side elevational view of the novel brush holder and the brushes
sustained thereby, showing also in side elevation a single commutator strip upon
which the brushes rest.
Figure 3 is a part plan part sectional view of the novel brush holder and
brushes; and,
Figure 4 a detail side elevational view of one of the brushes illustrating its
central clamping slot or opening, the clamping screw therefor being shown in
sectional view.

page_text: Referring now to the drawings in detail in all of which like letters of reference
represent like parts where used in the various figures.
A represents the commutator of a motor or dynamo electric machine and A' a
single commutator strip thereof, the latter being shown in side elevation in Figure 2
to illustrate more clearly how the improvement makes it possible to utilize a
maximum surface of the commutator in the direction of the length of the strips
thereof.
Ris the rocker arm of well known form for large dynamo electric machines,
to which the novel brush holder is adjustably secured by an L-shaped arm or
stud C, vertical adjustability of the entire holder being effected by a clamp R,
secured to the rocker arm by bolts, as shown, this feature of adjustment adapting
the entire brush holder to be moved vertically as the commutator wears away.
S is a sleeve of hard rubber, vulcanized fibre or equivalent material, and W W¹
are washers of similar material for insulating the brush holder in the usual manner
from the rocker arm R and the frame of the machine, and P is a binding post
for the conductor running to the source of current use or supply.
The lower and rear end of the arm or stud C has lateral extensions to which are
secured by rivets, two pairs of copper brush sustaining springs EE' E2E³, and
to the forward or free ends of these springs are secured in a similar manner metallic
conducting blocks FF provided with screw-threaded holes adapted to receive
clamping screws G G³, for rigidly securing by clamps G and G¹ adjacent
brushes B B, preferably of carbon or graphite, and having each a slot or opening
through its centre for receiving its clamping screw, as more clearly shown in
Figure 4.
D and D are adjusting springs having holes for corresponding adjusting thumb-
screws TT, the lower ends of which pass through screw-holes in additional side
lugs on the arm or stud C. The opposite ends of the flat springs D and 11 rest
respectively upon the ends of the side lugs which support the springs E E' E² E³
and free ends of the springs EE2, the function of said springs DD and thumb-
screws TT being to compensate or adjust for tension and wear of the brushes.
The operation of this novel brush holder is obvious in view of the structure
described, it being apparent that by virtue of the pairs of springs E E¹ and E2 E3
their supported conducting blocks FF, clamps GG and clamping screws G2G³,
the adjacent carbon brushes B and B will be held firmly so that they abut always
against each other laterally and hence never permit of any possibility of ridges
being worn on the commutator between them, as is now possible with existing
double brushes yieldingly supported.
It is also obvious that this novel form of brush with its central sustaining open-
ing makes it possible to utilize a maximum surface of the commutator in the
direction of the length of the commutator strips, there being no side or lateral
supports for the brush. It will also be seen that the two pairs of sustaining
springs EEEE3 by means of their parallelism, the parallel adjustability of their
supporting stud C and the parallel adjustability of the brushes B B¹ will always
cause said brushes to move in a plane parallel with their starting positions, so
that they will always bear with their entire end surfaces against the commutator,
as they or the commutator are worn away.
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. A brush holder having adjacent brushes rigidly clamped against conducting
pieces or blocks which permit them to abut against each other, said conducting
blocks in turn being securely fastened to an arm or stud by means of flexible
arms or springs, substantially as described.
2. A brush holder of the kind above claimed provided with means for imparting
a parallel motion to the conducting blocks without the use of sliding contacts,
substantially as described.

page_text: 3. A brush holder consisting of an arm or stud adjustably secured to a rocker
arm in combination with a pair of brushes located side by side and resting against
each other, together with a pair of brush supporting springs secured at one end
to the aforesaid arm or stud and at the other to contact blocks to which the afore-
said brushes are clamped, and adjustable means connecting said springs with the
aforesaid arm or stud with or without means for varying the pressure of the brushes
on the commutator, the arrangement being such that the brushes always bear
against each other laterally and maintain a parallelism of movement during their
entire life, substantially as described.
4. A brush holder constructed substantially as described with reference to the
accompanying drawings and for the purposes specified.
HASELTINE, LAKE, & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.
HASELTINE, LAKE, & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.