Year: 1887

page_text: Date of Application, 7th Apr., 1887
Complete Left, 7th Feb., 1888
Complete Accepted, 16th Mar., 1888
We, ALEXANDER PELHAM TROTTER, and WALTER THOMAS GOOLDEN, both of
2 Victoria Mansions, Westminster, in the county of Middlesex, Electrical Engineers,
do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the method of constructing the holders
used for carrying the "brushes" that are employed for collecting the current from
the commutator of a dynamo electric machine, and has for its object the providing of
means whereby the said brushes may be more readily and accurately adjusted than
obtains with apparatus of the kind as heretofore constructed.
The adjustment of the brushes is effected by so constructing the holder as to allow
of the brush being traversed in a direction perpendicular to the axis of rotation of the
commutator, or at any desired degree of obliquity to such axis, the traversing being
effected and controlled by the motion of a screw.
The holder consists essentially of two main parts and is so constructed as to allow of
one of its parts being rigidly attached to, but insulated from, the dynamo by any
suitable means, while the second part in which the brush and its traversing arrange-
ment are mounted, is capable of movement so as to allow of the brush being lifted or
removed from contact with the commutator, the brush, when in work, being held
firmly in contact with the commutator, with a pressure which can be accurately
adjusted, by means of a spring connected at one end to an arm projecting from the
moveable part, and suitably attached at its other end to an adjusting screw, working
in the fixed part.
The necessary movement for lifting the brushes may be imparted by a cam like piece
pivotted on the moveable part and working against a pin on the fixed part, or by other
suitable means. The moveable part of the holder is provided with a suitably formed
box like opening or guide through which the brush passes. This guide is fitted with
a strong (spiral) spring which pressing on the brush serves to steady it and to allow of
a longitudinal movement being imparted to it.
A traversing screw suitably mounted at one end so as to be capable of free rotation
is so placed as to be parallel to the direction of the motion which it is desired to impart to

page_text: the brush, and carries a nut or sleeve. This nut or sleeve is so formed as to allow of
the end of the brush remote from the commutator being clamped to it, and if now the
brush is placed in situ and clamped to the nut or sleeve it follows, by rotating the
traversing screw in one direction or the other that the brush will either advance towards
or recede from the commutator with a perfectly uniform motion.
In the case of a very broad commutator where it is necessary to employ two or
more brushes, side by side, each brush may have its own separate traversing screw, or
a single screw may suffice for the set of brushes, in which latter case the nut or sleeve
would be provided with two or more arms, according to the number of brushes, each
arm terminating in a suitable clamp. The length of the nut or sleeve, axially, would
then be extended sufficiently to enable it to act as a guide.
Dotad this 7th day of Anil 1007

page_text: COMPLETE SPECIFICATION.
Improvements in Brush Holders for Dynamo Electric Machines.
We, ALEXANDER PELHAM TROTTER, and WALTER THOMAS GOOLDEN, both of
2 Victoria Mansions, Westminster, in the county of Middlesex, Electrical Engineers,
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 relates to improvements in the method of constructing the holders
used for carrying the "brushes" that are employed for collecting the current from
the commutator of a dynamo electric machine, and has for its object the providing of
means whereby the said brushes may be more readily and accurately adjusted than
obtains with apparatus of the kind as heretofore constructed.
In a brush holder constructed in accordance with this invention provision is made
whereby the brush may be traversed in a direction perpendicular to the axis of rotation
of the commutator, or at any desired degree of obliquity to such axis, the traversing
being effected and controlled by the motion of a screw.
According to this method of construction the holder consists essentially of two
main parts so arranged as to allow of one of them being rigidly attached to, but
insulated from, the dynamo by any suitable means, while the second part, in which the
brush and its traversing arrangement are mounted, is capable of movement so as to
allow of the brush being lifted or removed from contact with the commutator, the
brush, when in work, being held firmly in contact with the commutator by means of a
spring connected at one end to the lower end of an arm projecting from the moveable
part and suitably attached at its other end to an adjusting screw, working in the fixed
part of the holder.
The movement for lifting the brushes from off the commutator is imparted by a
cam like piece mounted on a spindle capable of rotation in a bearing formed for it in
the fixed part. The cam on being suitably moved bears against a projection on the
moveable part and so causes it to be tilted about the axis by which it is attached to
the fixed part.
The moveable part of the holder is provided with a suitably formed box like opening
or guide through which the brush passes.
This guide is fitted with a strong spiral spring which pressing on the brush serves to
aid in maintaining an uniform pressure on the commutator, and also to ensure a steady
longitudinal movement of the brush.
A traversing screw is so placed as to have its axis parallel to the direction of the
motion which it is desired to impart to the brush, and carries a sleeve pieco on its
unthreaded end. This sleeve piece is so formed as to allow of the end of the
brush, remote from the commutator, being clamped to it, and if now the brush is
placed in situ and clamped to the sleeve it follows that by rotating the traversing
screw in one direction or the other that the brush will either advance towards or
recede from the commutator with a perfectly uniform motion.

page_text: In the case of a very broad commutator where it is necessary to employ two or
more brushes, side by side, we have found it advisable to mount on one fixed part two
or more of the moveable parts each provided with its own tilting and traversing
arrangements and springs for ensuring uniformity of pressure and travel of the
brush.
Having thus indicated the nature of our invention we will now proceed to more
particularly describe the same by reference to the annexed drawings.
Figure 1 is a side elevation, partly in section, of a brush holder constructed in
accordance with this invention, while Fig. 2 is an end view of part of the same
showing the means employed for lifting the brushes off the commutator.
In Fig. 1 the curved line CC shows part of the circumference of the commutator
on which the brush B,. B', bears.
The fixed part F. F. of the holder is attached and clamped to the insulated arm of
the usual brush carrier by means of the shouldered stud D which closing together the
slotted portion d serves to grip firmly the arm of the carrier turned to correspond
with the opening E.
The moveable part of the holder A; A, is secured to the fixed part by the pin e
about which it is free to rock as a centre. The lower end a of the arm G, forming
part of the moveable portion, is connected to the end a¹ of the regulating screw O by
a spiral spring and thus tends to draw the brush onto the commutator, the tension of
the spring being regulated by the thumb nut h.
The feed, or traverse, of the brush is effected by the handle H pinned to the outer
extremity of the unthreaded portion of the screw I, whose threaded portion engages
in a corresponding threaded opening in the moveable part of the holder.
The backward or forward motion of the screw I imparts a similar motion to the
sleeve clamp J and so traverses the brush.
The upper portion of the moveable part A is formed as a box or receptacle for the
strong spiral spring t held in compression by the threaded lid or cap K.
The lower end of the spring t pressing on the thickness piece T serves to steady the
movement of the brush during traversing and also aids in maintaining an uniform
pressure and flexibility of contact on the commutator.
When it is desired to lift the brush from off the commutator the handle H¹, made
of wood or other insulating material, is, as shown at Fig. 2, given a quarter turn to
the right, and by this means the cam like picce e is brought to bear against the pro-
jection and the whole of the moveable part A is thereby rocked about the pin c so
throwing the end B' of the brush up and off the commutator.
It will be understood that the fixed part F, may be so constructed as to carry two
or more of the moveable brush holders each of which would be provided with a
traversing arrangement and the means for lifting the brush as also the two springs, so
as to allow of each brush being lifted from off the commutator independently of the
others.
Having now particularly described and ascertained the nature of our said invention,
and in what manner the same is to be performed, we declare that what we
claim is :-
The hereinbefore described method of constructing the brush holders for dynamo
electric machines so as to allow of the brushes being accurately fed up to the commutator
and readily removed from contact therewith.
1000