Improvements in or relating to Dynamo Electric Machines.
Year: 1892

page_text: Date of Application, 13th Oct., 1892
Complete Specification Left, 20th Feb., 1893-Accepted, 1st Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in or relating to Dynamo Electric Machines.
I, JOHN PORTER THOMAS, of 13 Humberstone Gate, Leicester, Hotel Keeper,
do hereby declare the nature of this invention to be as follows:-
This invention relates to dynamo electric machines and is designed with a view
of causing the brushes to travel automatically to and fro on the commutator or
collector thus ensuring the surface of the latter being worn more smoothly than
otherwise and thereby avoiding the risk of "sparking "so liable with commutators,
upon which the brushes are in fixed contact therewith.
According to this invention the brush holders are mounted on a shaft or spindle
and may be moved to and fro on the latter in contact with the commutator by
means of a bell crank lever or equivalent means carried on a rocking shaft deriving
its motion from suitable levers or other intermediate mechanism connected to a
main shaft driven by belt and pulley or gearing from the usual driving shaft of a
gas or other engine."
Dated this 13th day of October 1892.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in or relating to Dynamo Electric Machines.
I, JOHN PORTER THOMAS of 13 Humberstone Gate, Leicester, Hotel Keeper
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 has reference to dynamo electric machines and is designed with a
view of causing the brushes (which heretofore, as far as I am aware, have been
fixed) to travel to and fro automatically in contact with the commutator.
In dynamo machines having fixed brushes the face of the commutator becomes
worn irregularly at the part in contact with the brushes which results in what is
known as "sparking" occurring and also in a fluctuation of the illuminating power
of the electric light.
By traversing the brushes to and fro over the surface of the commutator while
the latter is in motion a perfectly smooth face is imparted to the same thereby
avoiding the sparking referred to and ensuring a steady and uniform light.
The invention will be understood from the following description in reference to
the accompanying drawings wherein
Figure 1 is a side elevation, Figure 2 is an end elevation and Figure 3 is a plan
of a dynamo electric machine having brush traversing gear applied thereto in
accordance with this invention.
Figure 4 is a perspective view of the brush traversing gear detached from the
dynamo.
Figures 5 and 6 are side elevations of modifications of the brush traversing gear,
drawn to a larger scale than the preceding figures.
The construction and operation of a dynamo electric machine are well known so
that it is not necessary to describe them: such parts however, as are essential to a
clear understanding of the invention will be referred to.
A represents the brushes of a dynamo electric machine which are in contact

page_text: with the commutator B and are carried by brush holders A' mounted on the
spindle C in the well known manner.
Instead of the brush holders being fixed on the spindle C, I provide for them
moving to and fro thereon and for this purpose apply traversing gear thereto which
ensures the automatic to and fro movement of the brush holders. A' and the
brushes A during the working of the dynamo.
To effect this movement each of the brush holders is pivotted at D' to one end
of a horizontally reciprocating lever D the opposite end of which is forked, as
most clearly shown in Figure 4, and connected to the upper end of a vertical
vibrating arm F, the two latter being optionally connected to each other by a.
horizontal shaft E.
The lower ends of the said arms F' are secured in position by, set-screws F2,
Fig. 1, or otherwise on a rocking shaft F having bearings in brackets G attached
to the pedestal G¹.
The rocking shaft derives its motion from preferably an arm H movably con-
nected by a pin H¹ to the lever J, the latter having on its opposite end a band or
strap which encircles an eccentric K on the shaft L.
The shaft L has bearings in pillars L' bolted at L2 to the cross bar L³ and
may be driven by a pulley M thereon and a belt from the main shaft of a gas or
other engine or other source of power. It will be understood that the extent of
the movement imparted to the brushes A is such as to enable them to cover the
whole peripheral width of the commutator and thereby ensure the entire surface of
the latter being worn smooth.
I do not limit myself strictly to the precise arrangement of the traverse gear as
hereinbefore described as it is obvious that such mechanism may be modified in
various ways to permit of the brushes being automatically moved to and fro in
contact with the commutator in a line parallel to the axis of rotation of the
said commutator and other mechanical arrangements may be contrived to effect
the same purpose.
In Figures 5 and 6 two of such modifications are shown..
The same letters of reference as those in the preceding figures indicate
corresponding parts in the modifications.
In Figure 5, F is now the driving shaft carried in bearings G in the pedestal Gl
of the dynamo and may be driven by a pulley thereon from a gas or other engine
as before stated.
The shaft F has an eccentric K thereon which revolves within a strap or band J¹
having connected thereto at N' one arm N of a bell crank lever fulcrummed at N*
to the side of the pedestal G¹ and the other arm N³ of which is attached' at E to
the horizontally reciprocating lever D secured to the brush holders in the manner
hereinbefore described.
In Figure 6 the horizontally reciprocating lever D attached to the brush holder A¹
is connected directly to the eccentric K by the strap or band J thereon so as to
receive the requisite motion therefrom.
The eccentric is mounted on the shaft F and the latter is driven by a pulley from
the main power supply as hereinbefore mentioned.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that, what I
claim is :-
1. The application to a dynamo electric machine of mechanism for automatically
moving the brushes to and fro in contact with the commutator in a line parallel to
the axis of rotation of the said commutator for the purpose specified.
2. In a dynamo electric machine the combination with the brushes and brush
holders of horizontally reciprocating levers such as D and mechanism interposed
between them and the driving shaft for operating the same for the purpose
specified.
3. In a dynamo electric machine the combination with the brushes and brush

page_text: holders of horizontally reciprocating levers such as D vibrating arms such as F¹
and means for operating the said arms for the purpose specified.
4. In a dynamo electric machine the combination with the brushes and brush
holders of horizontally reciprocating levers such as D vibrating arms such as F¹
rocking shaft such as F and means for operating the said shaft for the purpose
specified.
5. In a dynamo electric machine the combination with the brushes and brush
holders of horizontally reciprocating levers such as D vibrating arms such as Fl
rocking shaft Farm H lever J eccentric such as K and shaft L substantially as
and for the purpose specified and illustrated in the accompanying drawings.
6. In a dynamo electric machine the combination with the brushes and brush
holders of horizontally reciprocating levers such as D bell crank lever such
as N N³ eccentric such as K and shaft F substantially as and for the purpose
specified and illustrated in Figure 5 of the accompanying drawings.
7. In a dynamo electric machine the combination with the brushes and brush
holders of horizontally reciprocating levers such as D eccentric such as K and
shaft F substantially as and for the purpose specified and illustrated in Figure 6
of the accompanying drawings.
8. In a dynamo electric machine the combination and arrangement of parts
constructing and operating substantially in the manner and for the purpose specified
and illustrated in the accompanying drawings.
Dated this 18th day of February 1893
JOHN PORTE
THOMAS.
Witness,
E. NORTH LEWIS,
Berridge Street Chambers, Leicester.
W. P. Thompson & Boult,
Agents for the Applicant.