Improvements in the Wearing Parts of Dynamo-electric Machinery.
Year: 1892

page_text: Date of Application, 4th Mar., 1892
Complete Specification Left, 24th Nov., 1892-Accepted, 4th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Wearing Parts of Dynamo-electric Machinery.
I, WILFRID L. SPENCE, of The Elms, Seymour Grove, Manchester, Engineer
do hereby declare the nature of this invention to be as follows:
In running dynamo-electric machinery the two parts subject to wear and the two
which require constant attention are the brushes and the bearings, and my invention
relates to improvements in detail whereby wear is reduced to a minimum on the
commutator and by means of which the bearings require oiling only at long intervals,
say, once a week.
My improved current-collecting device consists in a compound brush block of
copper or other suitable metal and carbon.
The carbon may take the form of a plate or rod, and in the former case I prefer
the following construction:-
Two blocks or plates of carbon are taken, of appropriate size, and between them
is sandwiched a sheet of copper or other suitable material of corresponding
dimensions; the three pieces are then rivetted or otherwise fastened together and
secured to the supporting device in any suitable manner. Fig. 1, Sheet 1 shows
the arrangement.
Also
Instead of a solid sheet of metal I may use a laminated strip, as Fig. 2 Sheet 1,
or one made up of one or more folds of wire gauze, Fig. 3 of the same sheet.
in the case of generating machines running only in one direction I may omit one of
the carbon plates, although, in general, two will be found more convenient.
Ordinary arc-light carbon rods of 11 or 15 millimetres diameter are well adapted
for the purpose, in this case I prefer the following disposition of parts. Either a
cored carbon is taken and the soft core removed or else a solid rod has a hole drilled
through it.
A copper or other suitable metal core is then inserted and secured by screwing,
wedging or preferably by arranging that a shoulder on the bolt abuts against a
corresponding shoulder in the carbon block.
The core piece projects beyond the carbon, at the end remote from the com-
mutator, for the purpose of attachment to the supporting device and for connection
to the current-carrying wires. The mode of attachment which I prefer is to have
a small collar on this end of the bolt which serves to retain in place a clip spring
over the collar and between it and the support. A. reference to Fig. 4 Sheet 1, will
make the arrangement clear: is the brush block of carbon; the metal core passes
right through from front to back and projects as shown.
A brass fixing, e, serves to stiffen the brush; is the flexible cable-terminal;
and, c, a spring clip, the particular form shown being known as the "circlip."
A slightly different arrangement is shown in Fig. 5 the core here not coming
flush up to the wearing surface. A rubber or steel spring washer is inserted to
take up any slackness. In Fig. 6 the collar is shown as a nut instead of being
hammered over.
In Fig. 7 the parts are somewhat simplified; Fig. 8 illustrates another method of
putting a shoulder on the core, the sleeve being "sweated" or screwed on.
It will be seen that the foregoing arrangements admit of a very rapid renewal of
blocks when worn.
In order to obtain an even wear on the commutator surface the blocks may be
displaced alternately up and down so as to overlap to a small extent, Fig. 9 shows
the plan.
Square blocks are shown in Fig. 10, and in this figure the core is shown laminated,
a conical roll of wire gauze being a suitable arrangement.

page_text: am aware that it has been proposed to use carbon plates or rods covered with
electrolytically deposited copper on the outside surfaces but this form of brush only
has the advantage of reducing the resistance of the carbon considered as a conductor
merely. If the copper be deposited to any appreciable thickness it will positively
aggravate the sparking. This will be obvious on referring to Fig. 11 which shows
the old plan, and comparing it with Fig. 12 which illustrates my arrangement.
In both cases the true line of commutation is supposed to be A B.
'will be seen that there are two diameters, a band a b', of commutation and that the
In Fig. 11 it
sections of the commutator lying between these lines are short circuited.
In the new plan this is not so, and the high resistance carbon on either side of the
copper brush greatly tends to choke down sparking.
My improvement relates, secondly, to a form of bearing which is continuously self
lubricating.
The essential feature in a type of bearing now well known consists of a turned
metal ring running over the revolving shaft and dipping into an oil bath contained
in the pedestal casting.
This arrangement has several disadvantages; in the first place, the brass liner if
such be used must be cut in two in the axial direction making practically two bushes
to fit; secondly, even for a very moderate immersion in the oil the diameter of the
ring must be large and this makes a bulky, heavy-looking bearing; and in addition
the ring is badly in the way when the armature has to be removed or replaced.
In my improved bearing a chain with detachable links is used, by this means a
single bush can be employed (cut away on top and a little on the sides), the chain
may dip to any extent in the oil bath without practically increasing the width at
all, and, by opening a pair of links, the armature can be removed without any
difficulty.
If owing to the speed of rotation being very high it is feared that the chain would
assume a circular shape it may be made to run under a pin or small wheel in
the bath.
This would constrain the chain within the predetermined limits.
The arrangement is shown in Figs. 13 and 14, Sheet 2.
D
7
WILFRID L. SPENCE.
COMPLETE SPECIFICATION.
Improvements in the Wearing Parts of Dynamo-electric Machinery.
I, WILFRID L. SPENCE of The Elms, Seymour Grove, Manchester, Civil
Engineer, 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 :-
In running dynamo electric machinery the two parts which require constant
attention are the brushes and the bearings, and my invention relates to improve-
ments in detail whereby wear is reduced to a minimum on the commutator and by
means of which the bearings require oiling only at long intervals, as, for instance,
once a week.
My improved current collecting device consists in a compound brush of carbon
and a metal, preferably copper or bronze. The carbon may take the form of a
plate or rod and, in the former case I prefer the following construction. Two
blocks or plates of carbon of appropriate-size are taken and between them is sand-
wiched a sheet of copper or other suitable metal of corresponding dimensions, the
three pieces may then, if desired, be rivetted, sewed or otherwise fastened together
and are secured to the supporting arrangement in any suitable manner. Instead of
a solid sheet of metal I may use a laminated strip, or one composed of one or more
folds of wire gauze, or of a series of thin wires laid together. Also in the case of

page_text: generating machines or of motors running only in one direction I may omit one of
the carbon plates although, in general, two will be found more convenient.
Ordinary are light carbon rods of good quality are well adapted for the purpose.
In this case I prefer the following disposition of parts: Either a cored carbon is
5 taken and the soft core removed, or else a solid rod has a hole drilled through. A
copper or other suitable metal core is then inserted and secured by screwing,
wedging, by arranging that a shoulder on the centre piece abuts against a corre-
sponding shoulder in the carbon block, or otherwise. The metal core piece may
and should pass completely through the block so as to be flush with the wearing
surface. At the end remote from the commutator this core projects beyond the
carbon for the purpose of attachment to the supporting device and for connection
to the current carrying wires. A very simple attachment is to have a small collar
on this end of the bolt which when passed through a hole in the support is retained
in place by a clip, c, sprung over the neck. A reference to the drawings left with
the Provisional Specification will make the arrangement clear. This clip permits
of a very ready removal and replacement of worn out blocks.
Figures 1 to 3 show my improved brush in the plate form and
Figures 4 to 9 illustrate the rod form of brush.
The rubbing block is carried in a metal holder, e, which is secured to the springy
plate backing, d. This holder is preferably open at the sides with a view to
economising space and so getting more brushes on to the commutator. The plate
backing or support may itself be shaped to form the holder either altogether or in
part as shown in Figure 7. A separate terminal, t, for the wire connection is
shown in Figures 4, 7 and 8B, and a spring washer, s, which is desirable is indicated
in Figures 1, 5, 6, 7 and 8³.
In order to obtain a more even wear on the commutator the blocks may be dis-
placed alternately up and down so as to overlap to a small extent as shewn in
Figure 9.
I am aware that it has been proposed to use carbon plates or rods, covered
externally with electrolytically deposited copper, as current collecting brushes but
this form is only the equivalent of a simple carbon block supported in a metal
holder which comes close up to the wearing surface. It merely tends to reduce the
resistance of the brush considered as a conductor while sparking is aggravated to
just the extent that the coating is effective.
My improved brush has the same low resistance, but in a greater degree, and
sparking is minimised by the carbon touching the commutator to either side of the
neutral line.
Figures 11 and 12 shew the difference between the old and the present methods
In the former all the bars in the angles a o a¹ and o bare short circuited and
will spark. In the case represented by Figure 12 there will be no sparking.
I am also aware that it has been proposed to use a main brush of copper and a
separate auxilliary one of carbon, and I make no claim to such an arrangement.
My improvements relate secondly to a form of bearing which is continuously self
lubricating. A type of journal now well known is lubricated by means of a turned
metal ring running over the revolving shaft and dipping into an oil bath contained
in the pedestal casting. This arrangement has several disadvantages :-the liner,
if such be used, must be cut in two in the axial direction making practically two
bushes to fit; secondly even for a very moderate immersion in the oil the diameter
of the ring must be great thus making
addition the ring is much in the way when the armature has to be removed and
a bulky, heavy-looking bearing, and in
replaced.
In my improved bearing a chain with detachable links is used thus enabling a
ingle bush, cut away on top and a little on the sides, to be employed. The chain
nay dip to any extent in the oil bath and the outside dimensions of the bearing
practically need not be enlarged at all. Lastly by means of the detachable links
he chain may be opened and the armature removed without difficulty. The chain
Iso carries more oil over the shaft than does a plain ring. The arrangement is

page_text: shewn on Sheet 2 of the drawings. Although a split bearing is illustrated the
invention is equally applicable to solid ones either with or without removeable
bushes.
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:
1. In brushes for dynamo electric machines the compound current collecting
block of carbon, and a metal, the metal bearing against the commutator on the
neutral line and the carbon at the side thereof, all in one piece or, being separate,
in one holder, and adapted to be fed together substantially as described.
2. The method of supporting a current collecting block by passing a metal core
\piece integral, therewith through an opening in the holder and fastening it in place
by a clip.spring over a collar, substantially as described.
3. In dynamo electric machines constructing the bearings with a detachable link
chain running over the shaft and dipping into an oil bath below.
4. My improvements in dynamo electric machines substantially as described.
Dated this 24th day of November 1892.
WILFRID L. SPENCE.