Improvements in Brushes for Electric Current Generating and Receiving Machines.
Year: 1892

page_text: Date of Application, 8th Oct., 1892
Complete Specification Left, 1st June, 1893-Accepted, 1st July, 1893
PROVISIONAL SPECIFICATION.
Improvements in Brushes for Electric Current Generating and
Receiving Machines.
A communication from LOUIS BOUDREAUX, of Paris, in the Republic of France.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Member of the Institution of Mechanical Engineers, do hereby declare the nature
of this invention to be as follows:-
This invention consists in an improved brush for generators or receivers of
electric currents.
The improved brush mainly consists of one or more superposed sheets being
preferably very thin plates of rolled metal (their thickness not exceeding a few
hundredths of a millimetre), and capable of being easily folded. One or more of
such superposed sheets are evenly folded in the ordinary manner on straight lines,
the folds being as tightly compressed as possible.
The object of the folding is to enable an electrical brush to be formed of one
sheet only and without any solution of continuity or break. Besides according as
the number of folds is greater or less, the flexibility of the brush will vary to the
desired extent, the result in all cases, however, being a spring of such remarkable
yieldingness and delicacy as cannot be obtained by any other means and a friction
of such lightness as will reduce to a minimum the wear both of the brush and
commutator.
In practice the folds may be arranged either tangentially transversely or at
right angles to the commutator.
It has been found by experiment that sheet metal (such as brass-foil well known
in the trade) of an approximate thickness of three hundredths of a millimetre is
very serviceable for the present purpose as it can readily be folded and forms very
durable electric brushes, which by reason of the lightness of their friction, are
hardly, if at all, subject to wear, while they never produce any wear of the
commutator, which, under their action only acquire a bright polished surface
affording additional evidence of the softness of the friction and of the insignificance
of wear.
When the end of the brush has, through use, assumed the concave shape
corresponding to the periphery of the commutator, its further wear is also
practically stopped so that the subsequent adjustment for the purpose of bringing
it closer to the commutator need only be resorted to at very long intervals of time.
Brass foil has only been mentioned above by way of example as it will be
understood that the invention is not to be confined to the employment of this
material, inasmuch as any suitable metal may be used, while the size and shape of
the improved brushes may vary indefinitely to suit requirements.
It is further obvious that brushes constructed according to this invention may
comprise additional parts made of wire or wire-gauze, soldered or connected
together with the main body of the brush in one or several pieces, by means of tin
solder or otherwise, or connected thereto in one piece or in sections by means of
any other material being a conductor or a non-conductor of electricity. Or they
may contain an admixture of various non-metallic materials, such as paper, mica,
asbestos fibre or fabric, silk tissue, worsted or cotton, etc. Or they may consist of
more than one kind of metal, reduced to the minimum thickness in a
rolling mill
and if required coated with deposits of kindred or other metals by any electro-
chemical, chemical, physical, or mechanical process.
Dated this 8th day of October 1899
ALFRED J. BOULT,
Chartered Patent Agent.

page_text: COMITEITE SPECIFICATION.
Improvements in Brushes for Electric Current Generating and
Receiving Machines.
A communication from LOUIS BOUDREAUX, of Paris, in France.
1, ALFRED JULIUS BOULT, of 323 High Holborn, in the County of Middlesex,
Chartered Patent Agent, 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 consists in an improved brush for generators or receivers of
electric currents, and will be best understood by reference to the accompanying
drawings in which :-
Figure 1 represents a brush constructed in accordance with this invention, in
contact with a commutator or collector.
Figure 2 is a perspective view of the brush with the upper fold raised so as to
show a number of sheets spread out or unfolded.
The improved brush mainly consists of one or more superposed sheets a being
preferably very thin plates of rolled metal sometimes known as "foil" (their
thickness not exceeding a few hundredths of a millimetre), and capable of being
easily folded. One or more of such superposed sheets are evenly folded in the
ordinary manner on straight lines, the folds being as tightly compressed as
possible.
The object of the folding is to enable an electric brush to be formed of one sheet
only and without any solution of continuity or break. Besides according as the
number of folds is greater or less, the flexibility of the brush will vary to the
desired extent, the result in all cases, however, being a spring of such remarkable
yieldingness and delicacy as cannot be obtained by any other means and a friction
of such lightness as will reduce to a minimum the wear both of the brush and
commutator.
In practice the folds may be arranged either tangentially, transversely, or at
right angles to the commutator.
It has been found by experiment that sheet metal (such as brass-foil well-known
in the trade) of an approximate thickness of three hundredths of a millimetre is
very serviceable for the present purpose as it can readily be folded and forms
very durable electric brushes, which, by reason of the lightness of their friction,
are hardly, if at all, subject to wear, while they never produce any wear of the
commutator which, under their action only acquires a bright polished surface
affording additional evidence of the softness of the friction and of the insignificance
of wear.
When the end of the brush has, through use, assumed the concave shape
corresponding to the periphery of the commutator, its further wear is also
practically stopped, so that the subsequent adjustment for the purpose of bringing
it closer to the commutator need only be resorted to at very long intervals of time.
Brass foil has only been mentioned above by way of example, as it will be
understood that the invention is not to be confined to the employment of this
material, inasmuch as any suitable metal may be used; while the size and shape of
the improved brushes may vary indefinitely to suit requirements.
It is further obvious that brushes constructed according to this invention may
comprise additional parts made of wire or wire-gauze, soldered or connected
together with the main body of the brush in one or several pieces, by means of tim
solder or otherwise, or connected thereto in one piece or in sections by means of
any other material being a conductor or a non-conductor of electricity. Or they
may contain an admixture of various non-metallic materials, such as paper, mica,
asbestos fibre or fabric, silk tissue, worsted or cotton, etc. Or they may consist of

page_text: more than one kind of metal, reduced to the minimum thickness in a rolling mill
and if required coated with deposits of kindred or other metals by any electro-
chemical, chemical, physical or mechanical process.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent, and in what manner the
same is to be performed, I declare that what I claim is :-
1. A brush for dynamos and other electric machines composed wholly or partly
of metal in the form of foil.
2. A brush for dynamos and other electric machines composed wholly or partly
of one or more superposed folded sheets of metal foil substantially as described and
illustrated in the accompanying drawings.
3. A brush for dynamos and other electric machines composed of superposed
folded sheets of foil of the same or different metals substantially as described.
4. A brush for dynamos and other electric machines composed wholly or partly
of one or more superposed folded sheets of metal foil coated with deposits of
kindred or other metals substantially as described.
Duted this 25th day of May 1802
W. P. THOMPSON & BOULT,
Agents for the Applicant.