An Improved Brush for Dynamos and Motors.
Year: 1890

page_text: Date of Application, 14th May, 1890
Complete Specification Left, 16th Feb., 1891-Accepted, 28th Mar., 1891
PROVISIONAL SPECIFICATION.
An Improved Brush for Dynamos and Motors.
I, MORITZ IMMISCH, of 119, Torriano Avenue, Camden Town, London, in the
County of Middlesex, Electrician, do hereby declare the nature of this invention
to be as follows:-
This invention relates to a new form of carbon brush, whereby the advantages
of carbon are secured, whilst its disadvantages are avoided.
In order that the carbon block in contact with the commutator should easily
follow all vibrations caused either by irregularities of the commutator itself or by
imperfect foundations, or, in the case of tramcar work, by the vibration of the
vehicle, it is necessary that such block should fit loosely in its holder or frame, and
be forced into contact with the commutator by a spring. This necessary looseness
is a great inconvenience. In the first place it causes the contact between the
carbon block and its frame or holder to be imperfect, thus often throwing upon
the spring an excessive current which destroys or impairs its action by heating,
and, secondly, the fact of the contact between the block and its holder or frame
being necessarily a sliding one, a current passing from one of the sliding surfaces
to the other presents a considerable obstacle to the free movement of the block,
and causes the latter to stick or move sluggishly.
To obviate these defects I do not take off the current, as is now done, from the
frame or holder, but directly from the carbon block itself, by attaching thereto a
flexible conductor. For this purpose I preferably coat the block with copper by
electro-deposition or otherwise, except on its contact surface with the commutator,
and before so coating same I secure a plate of copper to the rear end of the block,
such plate being provided with an ear or lug to receive the end of the flexible
conductor, thus securing an intimate connection between the block and such
conductor.
T: 14th dow of Nov 1890
ALLISON BROS.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Brush for Dynamos and Motors.
I, MORITZ IMMISCH, of 119, Torriano Avenue, Camden Town, London, in the
County of Middlesex, Electrician, 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 invention relates to a new form of carbon brush, whereby the advantages of
carbon are secured, whilst its disadvantages are avoided.
In order that the carbon block in contact with the commutator should easily
follow all vibrations caused either by irregularities of the commutator itself or by
imperfect foundations, or, in the case of tramcar work, by the vibration of the
vehicle, it is necessary that such block should fit loosely in its holder or frame,
and be forced into contact with the commutator by a spring. This necessary
looseness is a great inconvenience. In the first place it causes the contact between
the carbon block and its frame or holder to be imperfect, thus often throwing upon
the spring an excessive current which destroys or impairs its action by heating,
and, secondly, the fact of the contact between the block and its holder or frame

page_text: being necessarily a sliding one, a current passing from one of the sliding surfaces to
the other presents a considerable obstacle to the free movement of the block, and
causes the latter to stick or move sluggishly.
To obviate these defects I do not take off the current, as is now done, from the
frame or holder; but directly from the carbon block itself, by attaching thereto a
flexible conductor. For this purpose I preferably coat the block with copper by
electro-deposition or otherwise, except on its contact surface with the commutator,
and before so coating same 1 secure a plate of copper to the rear end of the block,
such plate being provided with an ear or lug to receive the end of the flexible
conductor, thus securing an intimate connection between the block and such
conductor. Between the spring which forces the brush against the commutator
and such brush I interpose a disc or block of insulating material, so that the brush
is entirely insulated from the spring, thus forming an additional security against
any leakage should the insulation of the brush holder from any cause become
defective.
A suitable method of carrying the invention into effect is shown in the
accompanying drawings, in which :-
Fig. 1 is partly an end elevation and partly a transverse section of the
commutator and brushes,
Fig. 2 a plan view, and
Fig. 3 a longitudinal section of Fig. 1.
Fig. 4 is a plan view, and
Fig. 5 a longitudinal section of one of the brushes.
Fig. 6 is a longitudinal section, and
Fig. 7 a transverse section of the brush holder and the end of its frame.
A are the carbon brushes coated with copper a, except on the contact surface
with the commutator B, and having a plate of copper a¹ secured at the rear end of
the carbon block. The plate a¹ is provided with an ear or lug X in which a
flexible conductor C is secured to convey the current directly to or from the
brushes A.
The carbon blocks or brushes A are inserted in a holder D, through which they
can work freely, and a spring E forces each block into contact with the
commutator B, one end of such spring bearing on a block or disc of insulating
material F secured to the rear end of the carbon block A, so that the latter is
insulated from the spring. The tension of the springs E can be adjusted by means
of the screws G working through washers g, so as to enable the pressure of the
brushes upon the commutator to be regulated, and to allow for the brushes wearing
away.
Each brush holder D is carried at one end of a frame H, the position of which
can be shifted in relation to the end bearing I of the dynamo or motor upon which
it is mounted, so as to enable the lead of the brushes to be adjusted as required.
The set-screw / enables the frame H to be secured in the position to which it has
been shifted.
As shown in Figs. 6 and 7 the stem of each holder D is insulated from the
frame H by the sleeve d of insulating material, through which the stem passes,
such sleeve being carried in a block K mounted in ways in the frame H; and
against which block bears a screw L working through the end of the frame H, so
as to permit the frame D and its brushes A to be moved towards the commutator B
when necessary to do so on account of the wear of the brushes, and away there-
from when new brushes are inserted.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. The improved brush for dynamos and motors, consisting of a block of carbon
preferably coated with copper except on its contact surface with the commutator,
and provided with a plate of copper at its rear end, such plate having an ear or lug

page_text: to receive the end of the conductor to lead the current from or to such commutator,
substantially as specified.
2. The improved carbon brush consisting in a block of carbon coated with
copper and having the conductor to lead the current to or from the commutator
secured to the rear of such block of carbon, such brush being forced towards the
commutator by a spring acting upon a disc or block of insulating material placed
on the rear end of such carbon block, so that the latter is insulated from the
spring, substantially as specified.
3. The improved carbon brushes with their holders and frame for the
commutators of dynamos and motors, constructed and operating substantially as
specified.
Dated this 13th day of February 1891.
ALLISON BROS.,
Agents for the Applicant.