Improvements in Brush Holders for Dynamo Electric Machines.
Year: 1893

page_text: Date of Application, 23rd Dec., 1893
Complete Specification Left, 10th Sept., 1894-Accepted, 13th Oct., 1894
PROVISIONAL SPECIFICATION.
Improvements in Brush Holders for Dynamo Electric Machines.
I, ROOKES EVELYN BELL CROMPTON, Engineer, of Mansion House Buildings,
London, E.C. do hereby declare the nature of this invention to be as follows:-
My invention relates to brush holders of dynamo electric machines whether used
for continuous or alternate currents, and has for its object the cheapening of the
construction of such brush holders and also their simplification, so that the pressure
of the brushes on the commutator or collector may be easily adjusted while the
machine is at work, and also so that they may be casily thrown on or off the
commutator or collector. The construction of my improved brush holder is made
clear by means of Figures 1, 2, 3 and 4. Figure 1 is a longitudinal section;
Fig. 2 an end view and Figs. 3 and 4 are details.
My improved brush holder consists of two principal parts.
1. The brush box or holder proper :-This which is the movable part may be
constructed of any suitable material. That portion of it in which the brush is held
may be of any of the usual patterns, that shown in Figs. 1 and 2 consisting of a
box A in which the brush is held by means of the clamp screw G and lock nut H.
This brush box A is arranged to swivel on the brush spindle B in the usual
manner. From the lower portion two projecting pieces D. D. are extended.
Through these projecting pieces a pin E is fixed on which a bell crank lever K
turns. The second or fixed part of my improved brush holder consists of a
collar C which is securely fixed to the brush spindle B, either by means of a
nipping screw as shown in Fig. 1, or by a set screw or key or other suitable means.
A tube F, hereinafter called the spring box projects from this portion or t…..
holder and contains the spiral spring L by means of which the pressure of the
brush M is maintained on the commutator or collector N. One end of the spiral
spring L is attached to the short arm of the bell crank lever K, the other end
being attached to a nut through which the screw ( passes. By turning this screw
the nut is traversed forwards or backwards in the spring box F, and the tension of
the spring varied. To prevent the screw from turning when not required
through vibration or other cause a pin P is put through it which falls into a groove
in the end of the spring box F. From the end of the spring box F a catch Q
projects through which one end of the bell crank lever K passes. K is notched
at R, and it will be seen that owing to the tension of the spring L which is
attached to the short end of the bell crank lever there is always an outward
pressure of the long end of the bell crank lever away from the spring box F, so
that if K is in a suitable position the notch R will engage with the catch Q. The
position of the collar C on the brush spindle B is so arranged that when R is
engaged with Q the brush M is clear of the commutator or collector N. It will
be seen therefore that if K be moved towards the spring box F so that the notch R
is lifted clear of Q the tension of the spring L will pull the brush M forward on to
the commutator or collector N, and the notch R will assume a new position as
shown in Fig. 3. To take the brush M off the commutator or collector; N therefore
it is only necessary to press K forward by means of the button S in the direction
of the arrow.
It will also be seen that by the use of the bell crank lever K I am
enabled by means of the single spring L to secure the necessary spring pressure of
the brush M on the commutator or collector N and also the spring pressure of the
outer end of the lever K on the catch Q.
The spring box F is shown in Fig. 1 constructed in one piece with the collar C,

page_text: but obviously it might be formed of a separate tube attached to C, or the tubular
form might be dispensed with altogether and a plain bracket such as is shown in
Fig. 4 might be used. To enable the screw O and the lever K to be safely
touched without risk of shock when the dynamo machine is at work, they are
provided with nobs or terminal pieces of any suitable insulating material. In cases
where a very large amount of current has to be collected by the brush M, to
convey this to the spindle B a flexible connection T is provided consisting of strips
of thin copper, or flexible stranded copper cord, or other suitable means so that the
greater portion of the current is conveyed directly from the brush M to the brush
spindle B without having to pass through these por tions of the brush box A which
turn on the brush spindle B.
Dated the 23rd day of December 1893.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.
Improvements in Brush Holders for Dynamo Electric Machines.
I ROOKES EVELYN BELL CROMPTON, Engineer, of Mansion House Buildings,
London E.C. 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 brush holders of dynamo electric machines whether used
for continuous or alternate currents, and has for its object the cheapening of the
construction of such brush holders and also their simplification, so that the
pressure of the brushes on the commutator or collector may be easily adjusted
while the machine is at work, and also so that they may be easily thrown on or
off the commutator or collector.
The construction of my improved brush holder is made clear by means of
Figures 1, 2, 3 and 4.
Figure 1 is a longitudinal section; Figure 2 an end view and Figures 3 and 4
are details.
My improved brush holder consists of two principal parts; The brush box or
holder proper-This which is the movable part may be constructed of any
suitable material.
That portion of it in which the brush is held may be of any of the usual
patterns, that shewn in Figs. 1 and 2 consisting of a box A in which the brush is
held by means of the clamp screw G and lock nut. H.
This brush box A is arranged to swivel on the brush spindle B in the usual
manner.
From the lower portion two projecting pieces D D are extended.
Through these projecting pieces a pin E is fixed on which a bell crauk lever K
turns.
The second or fixed part of my improved brush holder consists of a collar C
which is securely fixed to the brush spindle B, either by means of a nipping screw
as shown in Fig. 1, or by a set screw or key or other suitable means.
A tube F, hereinafter called the spring box projects from this portion of the brush
holder and contains the spiral spring L by means of which the pressure of the
brush M is maintained on the commutator or collector N.
One end of the spiral spring L is attached to the short arm of the bell crauk
lever K, the other end being attached to a nut through which the screw passes.
By turning this screw the nut is traversed forwards or backwards in the spring
box F, and the tension of the spring varied.

page_text: To prevent the screw O from turning when not required through vibration or
other cause a pin P is put through it which falls into a groove in the end of the
spring box F.
From the end of the spring box F a catch projects through which one end of the
bell crank lever K passes.
Kis notched at R, and it will be scen that owing to the tension of the
spring L which is attached to the short end of the bell crank lever there is
always an outward pressure of the long end of the bell crank lever away
from the spring box F so that if K is in a suitable position the notch R will
engage with the catch Q. The position of the collar C on the brush spindle B is
so arranged that when R is engaged with the brush M is clear of the commutator
or collector N.
It will be seen therefore that if K be moved towards the spring box F so that
the notch R is lifted clear of Q the tension of the spring L will pull the brush M
forward on to the commutator or collector N, and the notch R will assume a new
position as shown in Fig. 3.
To take the brush M off the commutator or collector N therefore it is only
necessary to press K forward by means of the button S in the direction of
the arrow.
It will also be seen that by the use of the bell crank lever K I am enabled by
means of the single spring L to secure the necessary spring pressure of the
brush M on the commutator or collector N and also the spring pressure of the outer
end of the lever K on the catch Q. The spring box is shown in Fig. 1
constructed in one piece with the collar C, but obviously it might be formed of a
separate tube attached to C, or the tubular form might be dispensed with altogether
and a plain bracket such as it shown in Fig. 4 might be used. To enable the
screw and the lever K to be safely touched without risk of shock when the
dynamo machine is at work, they are provided with knobs or terminal pieces of any
suitable insulating material. In cases where a very large amount of current has to
be collected by the brush M, to convey this to the spindle B a flexible connection T
is provided consisting of strips of thin copper, or flexible stranded copper cord or
other suitable means so that the greater portion of the current is conveyed directly
from the brush. M to the brush spindle B without having to pass through these
portions of the brush box A which turn on the brush spindle.
Having now particularly described and ascertained the nature of my said inveu-
tion, and in what manner the same is to be performed, I declare that what 1
claim is
In brush holders for dynamo electric machines
1. The construction or arrangement of parts of a brush holder substantially as
and for the purposes described.
2. The combination or arrangement of the bell crank lever K, spring L, spring
box or bracket. F and catch Q so that the one spring L serves the double purpose
of getting the necessary pressure of the brush M on the commutator N and also
the pressure of the long end of the bell crank lever K on the catch Q necessary
to cause the notch R to engage with catch when they are in the proper position,
all substantially as herein described.
3. The improved construction and arrangement of the brush holder parts so that
economy and simplicity of construction may be attained with increased facility for
connection, disconnection or adjustment whilst the machine is running substantially
as described and illustrated by the drawings annexed.
Dated the 10th day of September 1894.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.