IMPROVEMENTS IN COMMUTATORS FOR DYNAMO OR MAGNETO ELECTRIC MACHINES AND ELECTRIC MOTORS, ALSO APPLICABLE TO OTHER ELECTRICAL MOVING CONTACT SURFACES."
Year: 1881

page_text: "
LETTERS PATENT to Peter Jensen, of 35, Chancery Lane, in the County of
Middlesex, for an Invention of IMPROVEMENTS IN COMMUTATORS FOR
DYNAMO OR MAGNETO ELECTRIC MACHINES AND ELECTRIC MOTORS, ALSO
APPLICABLE TO OTHER ELECTRICAL MOVING CONTACT SURFACES." A com-
munication from abroad by Thomas Alva Edison, of Menlo Park, in the State
of New Jersey limited States of America
PROVISIONAL SPECIFICATION left by the said Peter Jensen at the Office
of the Commissioners of Patents on the 1st September 1881.
PETER JENSEN, of 83, Chancery Lane, in the County of Middlesex. ** IMPROVE
MENTS IN COMMUTATORS FOR DYNAMO OR MAGNETO ELECTRIC MACHINES, AND
ELECTRIC MOTORS. ALSO APPLICABLE TO OTHER ELECTRICAL MOVING CONTACT
SURFACES. (A communication from abroad by Thomas Alva Edison, of Menlo
Park, in the State of New Jersey, Linited States of America.)
In the use of dynamo or magnetic electric machines having commutators formed
of copper bars and brushes. strips, wheels, or other collectors also made of copper
and hearing on the commutators, it has been found that no matter how smooth the
surfaces are made, the resistance of the surface contact of the brushes on the com-
mutators is considerable, and sparks are formed which in powerful machines are
exceedingly large, and keep increasing in size as the commutator is roughened by
the destructive influence of the sparks.
The great resistance of copper surfaces in contact is due rather to a physical than
a mechanical action of the metal.
The object of this Invention is to produce commutators and brushes or other
collectors for dynamo or magneto electric machines, the surface contacts of which
will have a very low resistance, so as to reduce the spark to such a degree that it

page_text: will not burn the commutators or brushes. This is accomplished by amalgamating
the face of the commutator and also the brushes, strips, wheels, or other devices
used for collecting the electricity where they bear upon such commutator.
The amalgamated surfaces have such an affinity for each other that the resistance
of the contact to the passage of the current is low, and the spark is very much
reduced. The commutator bars and the brushes are made as usual of copper, which
is preferred for its good conducting properties, and the surfaces are amalgamated
directly with mercury; or (the preferred way) the commutator bars and the brushes
are faced with silver and afterwards amalgamated. It is evident that the Invention
could be applied to the commutators of electro motors and to other moving surface
contacts where it is desired to lessen the resistance.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Jenson in the Great Seal Patent Office on the 1st March
1982.
PETER JENSEN, of 33. Chancery Lane, in the County of Middlesex. IMPROVE-
MENTS IN COMMUTATORS FOR DYNAMO OR MAGNETO ELECTRIC MACHINES AND
ELECTRIC MOTORS, ALSO APPLICABLE TO OTHER ELECTRICAL MOVING CONTACT
SURFACES. A communication from abroad by Thomas Alva Edison, of Meulo
Park, in the State of New Jersey, United States of America.
In the use of dynamo or magneto electric machines having commutators formed
of copper bars and brushes, strips, wheels, or other collectors also made of copper
and bearing on the commutators, the communicator has found that no matter how
smooth the surfaces are made the resistance of the surface contact of the brushes on
the commutators is considerable, and sparks are formed which in powerful machines
such as the communicator designs to use in connection with his system of electrical
distribution are exceedingly large, and keep increasing in size as the commutator is
roughened by the destructive influence of the sparks.
The great resistance of copper surfaces in contact has been found by the commu-
nicator to be due rather to a physical than a mechanical action of the metal.
The object of this Invention is to produce commutators and brushes or other
collectors for dynamo or magneto electric machines, the surface contacts of which
will have a very low resistance, so as to reduce the spark to such a degree that it
will not burn the commutators or brushes.
This is accomplished by amalgamating the face of the commutator, and also the
brushes strips, wheels, or other devices used for collecting the electricity where
they bear upon such commutator.
The amalgamated surfaces have such an affinity for each other that the resistance
of the contact to the passage of the current is low, and the spark is very much
reduced.
The commutator bars and brushes are made as usual of copper, which is
preferred for its good conducting properties, and the surfaces are amalgamated
directly with mercury; or (the preferred way) the commutator bars and the brushes
are faced with silver and afterwards amalgamated.
It is evident that the Invention could be applied to the commutators of electro-
motors and to other moving surface contacts where it is desired to lessen the
resistance.
What is claimed is,-
First. The method of reducing the resistance of moving surface contacts, consisting
in amalgamating the contacting surfaces, substantially as set forth.
Second. The method of reducing the spark at the commutator of a dynamo or
magneto electric machine. consisting in amalgamating the contacting surfaces of
the commutator and the brushes, strips. wheels, or other collectors, substantially
as set forih.
Third. The combination of a commutator and its brushes, strips, wheels, or other
collectors, having amalgamated contacting surfaces, substantially as set forth.
In witness whereof, I, the said Peter Jensen, have hereunto set my hand
and seal. this Twenty eighth day of February, in the year of our Lord
One thousand eight hundred and eighty-two.
P. JENSEN. (L.S.)