Improvements in Electric Switches.
Year: 1895

page_text: Date of Application, 1st Nov., 1895
Complete Specification Left, 31st July, 1896-Accepted, 5th Sept., 1896
Improvements in Electric Switches.
We, FRANCIS HENRY NALDER and ALFRED SOAMES, both of 16 Red Lion
Street, Clerkenwell, in the County of Middlesex, Electrical Engineers, do hereby
declare the nature of this invention to be as follows:-
In electric switches for opening and closing circuits in which heavy currents
flow it is necessary that the metallic contacts should extend over a considerable
area; this condition is easily satisfied so long as the contact surfaces retain their
original forms. But in practice the contact surfaces are liable to be injured and'
roughened by the sparking which occurs when opening the circuit. We meet
this difficulty by providing the contact surface upon the plane face of a disc of
metal; either one or both of the surfaces forming a pair may be so arranged.
The disc is so mounted that it can be turned round to bring into use fresh portions
of its surface as the parts previously in operation become roughened by sparking.
The switch may be made in different forms; for example we may provide the
switch handle or lever with a crosshead on which four metal discs are mounted,
they are metallically connected in pairs whilst the pairs are effectually insulated
the one from the other and from the lever or handle.
Upon a suitable table or support four metal jaws are provided one for each
disc, they also are arranged in pairs. The interval between one of the jaws and the
next jaw is a gap in the positive lead of the circuit whilst the interval between
the other jaws is a gap in the negative lead. By a movement of the switch lever,
the four discs can be jammed into the four jaws and then the circuit is closed; by
an opposite movement of the switch lever the discs can be removed from the jaws.
and the circuit opened in both the leads.
The discs are capable of being turned round and locked fast upon the crosshead
when placed as desired.
The jaws may in each case consist of a pair of discs so arranged that a disc
upon the crosshead may be jammed into the interval between them.
In like manner we make switches to control two circuits, opening one and closing
the other by one movement of the switch lever; to do this we provide au
additional series of jaws which receive the discs on the switch lever when they are
out of the jaws of the first series.
The switches above described are double switches opening and closing both the
positive and the negative leads; for some purpose single switches opening one
only of the leads will suffice and such switches may be similarly constructed.
In some switches the contacts are made by so called "brushes" consisting of
flexible and elastic metal plates. To construct a double brush, switch we mount a
pair of brushes upon or in connection with the switch lever and effectually
insulated. We provide also discs to serve as contact surfaces, a pair for each
brush, and so arranged that the brush may carry the current from the flat face of
one disc to that of the other thus closing a gap in the electric lead. The discs in
every case are so arranged that when they get worn or injured by sparking they
can be turned partly round to bring a new portion of the plane surface into
position to make contact.
Dated this 1st day of November 1895.
ว
FRAS. I. NALDER.
ALFRED SOAMES.

page_text: Improvements in Electric Switches.
We,
FRANCIS HENRY NALDER and ALFRED SOAMES, both of 16 Red Lion
Street, Clerkenwell, 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
staternent :-
In electric switches for opening and closing circuits in which heavy currents
flow it is necessary that the metallic contacts should extend over a considerable
area; this condition is easily satisfied so long as the contact surfaces retain their
original forms. But in practice the contact surfaces are liable to be injured and
roughened by the sparking which occurs when opening the circuit. We meet this
difficulty by providing the contact surface upon the plane face of a disc of metal;
either one or both of the surfaces forming a pair may be so arranged. The disc
is so mounted that it can be turned round to bring into use fresh portions of its
surface as the parts previously in operation become roughened by sparking.
The switch may be made in different forms; for example we may provide the
switch handle or lever with a cross bead on which four metal discs are mounted,
they are metallically connected in pairs whilst the pairs are effectually insulated
the one from the other and from the lever or handle.
Upon a suitable table or support four metal jaws are provided one for each disc,
they also are arranged in pairs. The interval between one of the jaws and the
next jaw is a gap in the positive lead of the circuit whilst the interval between the
other jaws is a gap in the negative lead. By a movement of the switch lever
the four discs can be jammed into the four jaws and then the circuit is closed; by
an opposite movement of the switch lever the discs can be removed from the jaws
and the circuit opened in both the leads.
The discs are capable of being turned round and locked fast upon the crosshead
when placed as desired.
The jaws may in each case consist of a pair of discs so arranged that a disc upon
the crosshead may be jammed into the interval between them.
In like manner we make switches to control two circuits, opening one and
closing the other by one movement of the switch lever; to do this we provide an
additional series of jaws which receive the discs on the switch lever when they
are out of the jaws of the first series.
The switches above described are double switches opening and closing both the
positive and the negative leads; for some purposes single switches opening one
only of the leads will suffice and such switches may be similarly constructed.
In some switches the contacts are made by so called "brushes" consisting of
flexible and elastic metal plates. To construct a double brush switch we mount a
pair of brushes upon or in connection with the switch lever and effectually
insulated. We provide also discs to serve as contact surfaces, a pair for each
brush, and so arranged that the brush may carry the current from the flat face of
one disc to that of the other thus closing a gap in the electric lead. The discs in
every case are so arranged that when they get worn or injured by sparking they
can be turned partly round to bring a new portion of the plane surface into
position to make contact.
The annexed drawings illustrate our invention, Figure 1 is a side elevation and
Figure 2 is a plan partly in section.
a is a metal lever with a handle a¹ which may be of vulcanite. The lever is
pivotted at the end opposite to the handle to a bearing piece 6 which is securely
fixed upon a slab c which may be of slate. The lever has two transverse arms a² a
they are sheathed with vulcanite or other insulating material which is seen at d d.

page_text: Each
On each sheathing d a pair of discs e e are fixed, and made fast by a set screw et
which can be easily slackened and tightened again when it becomes necessary to
shift the disc around upon the arm. The discs of each pair and the connecting
tube or barrel are one piece of metal. There are eight brush contacts in the
arrangement shown; for each there is a block or fixing of metal f upon the
slab c and each is connected with one of the electric leads; clamping nuts provided
for the purpose are shown at 11. On each block f two pair of spring plates g g
are bolted and each plate is divided by a saw cut as the drawing indicates.
dise when in place is held between the spring plates g and has four elastic blades.
pressing firmly upon it on either side to make good electric contact.
ends of the blades are curved so that the disc may enter freely between them.
Figures 3, 4 and 5 show another example of the application of our invention..
Figure 3 is a side elevation. Figure 4 is an end elevation and Figure 5 is a plan
-in each figure there are parts omitted. In the arrangement here shown there
are two curved metal rockers k k each carrying a disc at either end. The discs.
are fixed to the rockers but in such manner that they can readily be shifted round
when needed.
The outer
The rockers are carried by insulated bearing blocks m fixed on the slab n.
oooo are four brush contacts connected with the electric leads as are also the
bearing blocks m; so the rockers and discs serve to establish electrical connection
between the blocks m and the brushes o o on one side or the other as the case may
be. p is a metal lever with a handle and guard disc of ebonite, it is pivotted upon
a block a fixed to the slab n and it is provided with two arms p' p' clothed with.
vulcanite. pp² are insulated rings upon the arms, and springs rr connect the
springs with the rockers. When the handle is moved over from side to side it
withdraws two of the discs from the brushes by means of the springs which as the
tension is increased cause a sudden movement of the rockers and immediately
afterwards the arms p' p' thrust the other discs into the brushes on the other side.
The dises are made as the drawing shows, larger on one side than the other, this
increases their durability as does also the rapid separation of the contact surfaces.
which the springs effect.
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:-
1. Electric switches having disc contacts, the contact surfaces being on the plane
faces of the discs and the discs being capable of being turned to renew the contact
surfaces when needed.
2. Electric switches substantially as described and illustrated by the annexed
drawings.
Dated this 9th day of July 1896.
FRAS. H. NALDER..
ALFRED SOAMES.