Improvements in and relating to Dynamo Electric Generator and Motor Collecting Brushes.
Year: 1896

page_text: . Date of Application, 11th Feb., 1896
Complete Specification Left, 5th Nov., 1896-Accepted, 30th Jan., 1897
Improvements in and relating to Dynamo Electric Generator and
Motor Collecting Brushes.
I GEORGE EDENSOR DORMAN of The Hawthorns, Newport Road, Stafford, in the
County of Stafford, Inventor do hereby declare the nature of this invention to be
as follows:-
My invention relates to improved brushes or apparatus for collecting the current
from dynamo electric generators and motors whereby the sparking such as usually
occurs may be greatly reduced. To this end I employ, several brushes on any
commutator, the said brushes being of carbon but I make each brush of different
resistance in a progressive series, and at the same time I make each successive
brush of an increased width, in a direction at right angles to the shaft, the first
brush being of low or no resistance and being connected directly to the mains,
the second brush being wider than the first and of higher resistance and I connect
it to the first brush or the mains through additional wire resistance, the third brush
is still wider and of higher resistance, by this means contact with each segment of
the revolving commutator is very gradually broken, whatever the direction of
revolution, the brushes being preferably fed radially, but not necessarily so. And
I support the brushes in a holder made of porcelain or other suitable material
furnished with grooves or steps in which the brushes slide, the device being made
in two balves, the brushes lying side by side and being insulated from one another
sideways by means of paper cemented to the brushes or by other insulation, the
whole being contained in a cast iron shell. Each brush being pressed forward by
a contact or contact arm bearing on its end, the contact or contact arm being
operated by a spring, the brushes all being connected directly to the mains in paralell
or each being connected thereto, through additional resistances, the resistance
increasing as the resistance of the carbon of the brush is increased, the resistance being
inserted in the contact arm which is broken therefor or between the contact arm and
the mains. In some cases where resistances are used the carbons may be successively
wider but all of the same resistance in themselves. The carbons made with resistance
may be used in the usual rocking holders shaped therefor, the brushes simply being
insulated sideways, or they may be operated in radial but separately insulated brush
holders, the holders being then insulated by a nonconducting sleeve on the brush
stud and by washers thereon. The resistance of the carbon is varied, by the
addition of foreign substances in their manufacture, as is well understood.
Dated this 10th day of February 1896.

page_text: DEL 3791M SEMIFICATION.
Improvements in and relating to Dynamo Electric Generator and
Motor Collecting Brushes.
I GEORGE EDENSOR DORMAN of The Green Hall, Lichfield Road, Stafford in the
County of Stafford, formerly of The Hawthorns, Newport Road Stafford in the
County of Stafford, Inventor, 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:-
My invention relates to improved brushes, or apparatus for collecting the current
from dynamo electric generators and motors, whereby the sparking such as usually
occurs, may be greatly reduced, and to this end I employ several brushes on any
commutator, the said brushes being of carbon, but I make each brush of different
resistance, in a progressive series and at the same time, I make each successive
brush, of an increased width, in a direction at right angles to the shaft, the first
brush being of low, or no resistance and being connected directly to the mains, the
second brush being wider than the first and of higher resistance and I connect it to
the mains through additional wire resistance, the third brush is still wider and of
higher resistance, by this means contact with each segment of the revolving
commutator is very gradually broken whatever, the direction of revolution, the
brushes being preferably fed radially but not necessarily so.
And I support the brushes in a holder made of porcelain or other suitable material
furnished with grooves or steps in which the brushes slide, the device being made
in two halves, the brushes lying side by side and being insulated from one another
sideways by means of paper cemented to the brushes or by other insulation, the
whole being contained in a cast iron shell. Each brush being pressed forward by a
contact or contact arm bearing on its end, the contact or contact arm being operated
by a spring, the brushes all being connected directly to the mains in parallel; or each
being connected thereto, through additional resistances the resistance increasing as
the resistance of the carbon of the brush is increased. The resistance being inserted
in the contact arms which are broken therefor or between the contact arm and the
mains.
In some cases where resistances are used the carbons may be successively
wider, but all of the same resistance in themselves. The carbons made with
resistance may be used in the usual rocking holders shaped therefor, the brushes
being simply insulated sideways, or they may be operated in radial but separately
insulated brush holders, the holders being then insulated by a nonconducting sleeve
on the brush stud, and by washers thereon. The resistance of the carbons is varied
by the addition of foreign substances, in their manufacture, as is well understood.
In the accompanying drawings, Fig. 1. shews a commutator, and side view of a
brush holder made according to this invention, A are the carbons, B is the contact
arm, in this case shewn without additional resistances as aforesaid in the said arm,
F is the pivot on which the arms B swing, D being the spring operating B, H is the
cast iron shell which may also be of brass; or other suitable metal enclosing the
porcelain or china ware holders I shewn in a front view of the holder at Fig. 2.
K are insulating pieces between which the usual rocker yoke arm is located, S the
screws by which the holder is attached to the rocker arm, L is the main, Fig. 3
shews a single carbon with paper insulation aforesaid at T, the carbons may be
square or rectangular, or circular. Fig. 4. shews one half of the porcelain holder
Figs. 5 and 6 indicate a broken contact arm, insulation being inserted at the joint M,
the resistance being shewn at O, around the said break.
The resistance O of insulated wire may lie against the contact arms or may be
carried to a distance.

page_text: When circular carbons are used the grooves in the holder will be semicircular and
the carbons may be insulated all round, with a paper sheath as aforesaid.
The total resistance of each carbon is greater or less than that of the adjacent
carbons.
I do not bind myself to the precise method of pressing the carbons shewn, as many
devices may be used, with or without additional resistances, the said resistances being
always between the carbons and the cast iron or brass shell or main.
The width of the carbons may increase by thirty seconds of an inch or more,
the low resistance or first carbon being of the usual width, and the resistance of the
carbons and additional resistances may increase as largely as possible, leaving the
adjacent narrower and lower resistance carbon sparkless, the resistances being found
for each machine by trial, carbons being added till sparking is entirely eliminated,
or untill the widest or highest resistance carbon becomes wider than is desirable,
as is well understood.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is,
1st. In a dynamo or motor collecting brush, two or more carbons or equivalent
means, made of increasing width and resistance substantially as and for the purpose
herein described and shewn.
2nd. In a dynamo or motor collecting brush, two or more carbons or equivalent
means of increasing width and with increasing resistances connected thereto,
substantially as and for the purpose herein described and shewn.
3rd. In a dynamo or motor collecting brush, two or more carbons or equivalent
means insulated at the sides substantially as herein described and shewn.
Dated this 4th day of November 1896.
GEORGE EDENSOR DORMAN.