Switch for Electrical Circuits.
Year: 1892

page_text: Date of Application (in United Kingdom), 23rd Mar., 1892
Complete Specification Left, 29th Nov., 1892-Accepted, 7th Jan., 1893
PROVISIONAL SPECIFICATION.
Switch for Electrical Circuits.
I, EDWARD HIBBERD JOHNSON, of 44 Broad Street, in the City, County and
State of New York, in the United States of America, Electrician, do hereby
declare the nature of this invention to be as follows:-
The present invention relates to that class of circuit making and breaking
devices generally known as snap switches, that is, switches in which the switch
arm or contact is thrown by a spring to cause an instantaneous make and break of
The switch
the circuit, to avoid the formation of a hurtful arc at the contacts.
which forms the subject-matter of this application is well adapted for use with
circuits carrying currents of any character, but is designed more especially for
currents of considerable quantity and high tension, the construction being such
that dangerous heating at the contacts while the circuit is closed, or arcing on
opening the circuit, is practically impossible, and the construction is such that
should the contacts begin to heat from any cause, they become more firmly
pressed together by the expansion of the metals and their carrying capacity is
thereby automatically increased. In this snap switch the contacts are preferably
rigid plates or blocks, instead of yielding springs, and when the switch is operated
to close the circuit, the contacts are firmly wedged together and held between two
rigid or unyielding surfaces or bodies, as in a vice, the spring which is designed
to throw the movable contact exerting its whole force to wedge the contacts
together. Other important features and advantages will appear in the following
description.
In constructing this switch I take an insulating base of cup form and pre-
ferably of porcelain or other rigid and refractory insulating material, and mount
circuit terminals just within the rim of the base. To these terminals the circuit
wires are connected. Each of the terminals is provided at one end with a contact
portion, the upper faces of which are preferably in the same plane. These contact
faces are inclined or bevelled through a large portion of their length, but are
flattened for a greater or less distance at the end at which contact is broken. The
ends of the contact portions of the terminals are inclined or bevelled outward, sc
that when the connecting plate leaves the terminals, it has no tendency to form an
arc between the two adjacent edges or corners of the terminals, but any arc to be
formed must bridge the distance between the outer corners of the terminals. At
the centre of the base is fixed a screw threaded sleeve. provide an insulating
plate or screen having openings adapted to fit over the terminal contacts, and a
central sleeve to enclose the main bodies of the terminals and the connecting devices
carried by the base.
The second or upper section of the switch consists of a movable body consisting,
preferably, of a metal plate of sufficient thickness to be rigid, that is, to resist the
tendency to bend or yield under any strain which is put upon it in the ordinary
use of the switch, or which may be imposed by the expansion of the contacts
under high degrees of heat, an inner insulating plate, and an outer insulating plate.

page_text: In the latter plate are two dove tailed openings, in which two metal connecting
plates or blocks are fitted, and midway between them are two similar but smaller
openings in which are fitted two detent plates. The inner insulating plate is pro-
vided, immediately under the centre of the metal connecting plates, with raised
ribs, only partially as wide as said plates. The connecting plates have inclined or
bevelled faces, as already described, in connection with the terminal contacts.
Said connecting plates are preferably grooved through the centre, and an insulating
screen in the form of a ring is set into said grooves and into a corresponding
groove in the outer insulating plate. When the switch is built up, this screen
extends between the contact terminals, but it is evidently not necessary that the
ring should be carried by the movable member. The detent plates are only one
half as wide and are placed in line with but one set of the contact terminals. At
the centre of this member of the switch, and preferably formed integral with the
outer insulating plate, is an internally screw threaded sleeve, into which works a
metal screw formed at the bottom of a square spindle, on to which fit a sleeve and
handle. Through the centre of the handle, sleeve and spindle, passes a screw, the
head of which is adapted to bear against a shoulder within the sleeve, and the
lower end of which is adapted to screw into the screw threaded sleeve at
the centre of the base, a shoulder on the shank of the screw bearing against the
top of said sleeve. The actuating spring has one end connected to the movable
metal plate and the other end connected to a disc or collar which moves with the
handle and square spindle. A cap may cover the upper part of the switch. The
base is secured to a wall or other support and constitutes the fixed member of
the switch, while the other section forms the movable member of the switch.
When the parts of the switch are put together the actuating spring will be
given an initial tension. When the handle is grasped and turned two operations
take place, namely, since the square screw-threaded spindle is held from longi-
tudinal motion, as it is turned the movable member of the switch will ride up on
the thread, thereby tending to separate the bevelled connecting or contact plates
from the bevelled terminal contacts, that is, to move them directly away from each
other in a direction parallel to the spindle, so that they can pass each other
without much friction, and at the same time the spring is put under increased
tension, so that when the flat faces of the connecting plates and terminals come
together, the spring will have sufficient tension to throw the movable member
forward instantaneously and with great force. The flat faces allow the contacts
to move forward when they have been separated far enough to bring the highest
points of the bevels adjacent to each other. It will be clear that if we start with
the circuit closed, the first movement of the switch will break the circuit and bring
the movable member to rest with the detent plates bearing against the contact
faces of the outer terminals; while this arrests the movable member, it holds the
circuit open.
When the switch is again moved in the same direction, since the
switch is constructed to move forward whether the circuit is to be made or whether
it is to be broken, the broad connecting plates are thrown forward and rest on the
contact faces of the terminals, thereby connecting them and completing the circuit.
It may happen that one contact surface will be a trifle lower than the other surface,
and in this case if the connecting plates were immovable, bad contact, or no contact,
with one of the terminals would be obtained, but by providing the ribs behind the
plates, they are allowed to rock transversely, and hence can accommodate them-
selves to any slight irregularities in the contact surfaces. Since the spring throws
the wedge shaped connecting plates forward against the wedge shaped terminal
contacts with a good deal of force, and since both the connecting plates and the
terminals are held rigidly from moving in a direction away from each other, the
best possible contact is obtained, and a contact which is capable of carrying all
the current which the metal of the terminals and binding posts is capable of con-
ducting. If heating occurs at the points of contact whereby the metal is expanded,
the effect will be to cause more perfect contact owing to the rigid support of the
parts, thereby automatically increasing the conductivity at the contacts, and

page_text: enabling the switch to carry more current.
The construction of the switch is such
that when the circuit is closed, it is permanently locked against reverse movement
by the arrangement of the screw threads, and can only be operated by a positive
forward movement. In switches having yielding spring contacts, the quality of
the contact is dependent on the strength of the springs, and when the springs
become heated, as frequently happens, their resiliency is impaired, thereby
lowering the efficiency of the switch. This trouble is avoided in the switch above
described.
Dated thi. 02-1 day of March 1902
EDWARD H. JOHNSON,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.
COMPLETE SPECIFICATION.
Switch for Electrical Circuits.
I, EDWARD HIBBERD JOHNSON of 44 Broad Street, New York City, in the
County and State of New York in the United States of America Electrician do
hereby declare the nature of the said invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
The present invention relates to that class of circuit making and breaking devices
generally known as snap switches; that is, switches in which the switch-arm or
contact is thrown by a spring, to cause an instantaneous make and break of the
circuit, to avoid the formation of a hurtful arc at the contacts. The switch which
forms the subject-matter of this application is well adapted for use with circuits
carrying currents of any character, but designed more especially for currents of
considerable quantity and high tension, the construction being such that dangerous
heating at the contacts while the circuit is closed, or arcing on opening the circuit
is practically impossible, and the construction is such that should the contacts begin
to heat from any cause they become more firmly pressed together by the expansion
of the metals, and their carrying capacity is thereby automatically increased.
this snap switch the contacts are preferably rigid plates or blocks, instead of
yielding springs, and when the switch is operated to close the circuit the contacts
are firmly wedged together and held between two rigid or unyielding surfaces or
bodies, as in a vice, the spring which is designed to throw the moveable contact
exerting its whole force to wedge the contacts together. Other important features
and advantages will appear in the following description.
In the accompanying drawings
Figure 1. is a side view of the preferred form of my improved switch.
In
Figure 2. is a central section of the upper-portion of the switch, on line x, x, of
Figure 1.
Figure 2 is a cross section on line y. y. of Figure 1.
Figure 3. is a plan view of the lower section of the switch.
Figure 4 is a plan view of an insulating plate adapted to fit over the lower section
of the switch; and
Figure 5 is an inverted plan of the upper section of the switch.
In constructing this switch I take an insulating base, 1, of cup form, and
preferably of porcelain or other rigid and refractory insulating material, and mount
circuit terminals 2, 3, just within the rim of the base. To these terminals the
circuit wires 4, 5, are connected. Each of the terminals is provided at one end
with a contact portion 6, the upper faces of which are preferably in the same
plane.
These contact faces are inclined or bevelled through a large portion of their
length, but are flattened for a greater or less distance at the end at which contact
is broken, as indicated at 7. The ends of the contact portions of the terminals are

page_text: inclined or bevelled outward, as shown at 8, so that when the connecting plate
leaves the terminals, it has no tendency to form an arc between the two adjacent
edges or corners of the terminals but any arc to be formed must bridge the distance
between the outer corners 9, of the terminals. At the centre of the base is fixed
a screw-threaded sleeve 10; 11 is an insulating plate, or screen having
openings 12, adapted to fit over the terminal contacts, and the central sleeve 10,
to enclose the main bodies of the terminals and the connecting devices carried
by the base.
The second or upper section of the switch consists of a movable body consisting,
preferably of a metal plate 13 of sufficient thickness to be rigid, that is, to resist
the tendency to bend or yield under any strain which is put upon it in the ordinary
use of the switch, or which may be imposed by the expansion of the contacts under
high degrees of heat, an insulating plate 14, and an outer insulating plate 15. In the
latter plate are two dovetailed openings 16 in which the connecting plates or
blocks 17 are fitted, and midway between them are two similar but smaller openings
in which are the blocks 20.
The plate 14 is provided immediately under the centre of the plates 17 with
raised ribs 18 only partially as wide as said plates. The plates 17 have inclined
or bevelled faces, as already described, in connection with the terminal contacts 6.
The contact or connecting plates 17 are preferably grooved through the centre,
and an insulating screen in the form of a ring 19 is set into said grooves and into a
corresponding groove in the plate 15. When the switch is built up this screen
extends between the contact portions 6, but it is evidently not necessary that the
ring should be carried by the movable member. The detent plates 20 are only
one half as wide, and are placed in line with but one set of the contact terminals
as shown in Figure 5. At the centre of this member of the switch, and preferably
formed integral with the plate 15, is an internally screw-threaded sleeve 21 into
which works the metal screw 22 formed at the bottom of the square spindle 23
onto which fit the sleeve and handle, 24, 25. Through the centre of the handle,
sleeve and spindle passes a screw 26 the head of which is adapted to bear against
the shoulder 27, and the lower end of which is adapted to screw into the sleeve 10
on the base, the shoulder 28 bearing against the top of said sleeve. 29 is a spring,
one end of which is connected to the plate 13 at 30, and the other end of which is
connected to the disc or collar 31, which moves with the handle 25 and spindle 23,
32 is a cap which covers the upper part of the switch. The base is secured to a
wall or other support and constitutes the fixed member of the switch, while the
other section forms the movable member of the switch.
When the parts of the switch are put together, the spring 29, will be given an
initial tension. When the handle is grasped and turned two operations take place,
namely, since the screw-threaded spindle 23 is held from longitudinal motion as it
is turned the movable member of the switch will ride up on the thread, thereby
tending to separate the bevelled connecting or contact plates from the bevelled
terminal contacts, that is to move them directly away from each other in a direction
parallel to the spindle, so that they can pass each other without much friction, and
at the same time the spring 29 is put under increased tension, so that when the flat
faces 7 of the connecting plates and terminals come together, the spring will have
sufficient tension to throw the movable member forward instantaneously and with
great force. The flat faces 7 allow the contacts to move forward when they have
been separated far enough to bring the highest points of the bevels adjacent to
each other. It will be clear that if we start with the circuit closed, the first
movement of the switch will break the circuit, and bring the moveable member to
rest with the detent plates 20 bearing against the contact faces of the outer
terminals 2; while this arrests the moveable member it holds the circuit open.
When the switch is again moved in the same direction, since the switch is con-
structed to move forward whether the circuit is to be made or whether it is to be
broken, the broad plates 17 are thrown forward and rest on the contact faces of the
terminals 2, 3, thereby connecting them and completing the circuit. It may happen

page_text: that one contact surface will be a trifle lower than the other surface, and in this
case if the plates 17 were immovable, bad contact, or no contact, with one of the
terminals would be obtained, but by providing the ribs 18 behind the plates 17,
they are allowed to rock transversely and hence can accommodate themselves to
any slight irregularities in the contact surfaces. Since the spring throws the
wedge-shaped connecting plates forward against the wedge shaped terminal contacts
with a good deal of force, and since both the connecting plates and the terminals
are held rigidly from moving in a direction away from each other, the best possible
contact is obtained and a contact which is capable of carrying all the current which
the metal of the terminals and binding-posts is capable of conducting. If heating
occurs at the points of contact whereby the metal is expanded, the effect will be
to cause more perfect contact, owing to the rigid support of the parts thereby
automatically increasing the conductivity at the contacts, and enabling the switch
to carry more current. The construction of the switch is such that when the
circuit is closed it is permanently locked against reverse movement by the arrange-
ment of the screw-threads and can only be operated by a positive forward movement.
In switches having yielding spring contacts, the quality of the contact is dependent
on the strength of the springs, and when the springs become heated, as frequently
happens their resiliency is impaired, thereby lowering the efficiency of the switch.
This trouble is avoided in the switch above described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :
1. The combination, in a switch, of two rigid members corresponding to the jaws
of a vice one of which members is movable repeatedly in the same direction in
making and breaking circuit, contacts carried by the switch members, which when
the circuit is closed are held in contact between said rigid members, said members
being positively held from moving away from each other, and means for disengaging
the contacts, substantially as described.
2. The combination, in a switch, of two rigid members corresponding to the jaws
of a vice, one of which members is movable repeatedly in the same direction in
making and breaking the circuit, contacts carried on the two adjacent sides of the
rigid member, which contacts when the circuit is closed are held in contact
between said rigid members, means for separating the contacts, and a spring for
throwing one member with its contacts forward, substantially as described.
3. A circuit making and breaking switch having fixed and movable bevelled or
wedge-shaped contacts rigid and relatively movable bodies on two adjacent sides of
which the contacts are mounted, a spindle for the moving body, and means for
holding said bodies from moving away from each other in the direction of the length
of the spindle when the circuit is closed; whereby when the circuit is closed the
contacts are wedged and held together between said rigid bodies, substantially as
described.
4. The combination, in a snap switch, of a fixed and a movable rigid body having
a central spindle, the movable body being positively held from moving away from
the other body, a spring for throwing the movable body, and contact devices between
said bodies and in position to make and break contact as the movable member is
turned on its spindle, substantially as described.
5. A circuit making and breaking switch having fixed and movable contacts,
rigid bodies on two adjacent sides of which the contacts are located, which contacts
when the circuit is closed are pressed together between said rigid or unyielding
bodies, and permanent locking devices for locking the movable bodies and contacts
against reverse movement substantially as described.
6. A circuit making and breaking switch having fixed and movable rigid bodies
parallel with each other, contacts on two adjacent sides thereof, which when the
circuit is closed are wedged together between said rigid or unyielding bodies,
permanent locking devices for locking the movable member against a backward

page_text: movement, and a spring for throwing the movable contact when the switch is
operated, substantially as described.
7. The combination, in a switch, of a stationary rigid member, a movable rigid
member which is mounted so that it can be rotated in one direction only in making
and breaking the circuit, engaging contacts carried by said switch members and
means for rotating the movable member and for moving it toward or from the
stationary member, whereby when in one position said contacts are wedged
together between the rigid members, substantially as described.
8. A circuit making and breaking switch having fixed and movable rigid bodies,
contacts between two adjacent faces thereof, which when the circuit is closed are
wedged together between said bodies, the contacts having faces bevelled for a
portion only of their length, means for moving the contacts directly away from each
other, and means for advancing the movable contacts, said latter means operating
when the contacts have been moved far enough apart to bring the highest points
of the bevels on the contacts adjacent to each other, substantially as described.
9. The combination, in a switch, of two members carrying contacts, one member
being fixed and the other movable, a screw rotatable only in one direction and held
from longitudinal movement said screw working in a nut carried by the movable
member for moving it from the fixed member when the switch is moved to its open
position, and means for turning the movable member on the screw, thus causing it
to ride toward the fixed member, said screw constituting a spindle on which the
movable member turns substantially as described.
10. The combination, in a switch, of two members carrying contacts, one member
being fixed and the other being movable, a screw rotatable only in one direction,
said screw being threaded in such direction that when the screw is turned the
movable member will be carried away from the fixed member, and a spring
connected to the screw and to the movable member for throwing the latter
forward, thereby causing it to ride down on the screw-thread, substantially as
described.
11. The combination, in a switch, of two rigid members, contacts carried
thereby, which when the circuit is closed are held in contact between said rigid
members, which members are movable always in the same direction both in making
and breaking the circuit, means for disengaging the contacts, and means for
arresting the same before the circuit is again closed substantially as described.
12. The combination, in a switch, of two switch members, contacts carried
thereby, which when the circuit is closed are held in contact between said members,
a screw held from longitudinal movement engaging with and adapted to move one
member for disengaging the contacts, and a spring for throwing the movable
member with its contact forward, causing it to ride down on the screw, substantially
as described.
13. The combination, in a switch, of a base adapted to be connected to a
support, carrying circuit terminals separated from each other, a rigid movable
member fitting over the base and carrying connecting devices adapted to co-operate
with the terminals to electrically unite them, a screw threaded sleeve in said
movable member, a screw held from longitudinal movement but adapted to turn in
said sleeve, whereby when the screw is turned the movable member is raised and
permitted to advance substantially as described.
14. The combination, in a switch, of a base adapted to be connected to a support,
carrying circuit terminals separated from each other a rigid movable member fitting
over the base and carrying connecting devices adapted to co-operate with the
terminals to electrically unite them, a screw-threaded sleeve in said movable
member, a screw held from longitudinal movement but adapted to turn in said
sleeve, and a spring connected to the screw and to the movable member whereby
when the screw is turned the movable member is raised and advanced, substantially
as described.
15. The combination, in a circuit making and breaking switch, of a fixed
member, a member adapted to rotate, terminal contacts on the fixed member, an

page_text: insulating screen extending between the same, and a connecting plate or plates on
the movable member, substantially as described.
16. The combination, in a switch, of a connecting plate or device, and a pair of
terminals having contact faces and arranged adjacent to each other side by side,
the end of the contact portion of each terminal at which the connecting device
leaves it being inclined or bevelled away from the other terminal, whereby when
the connecting device breaks the circuit no arc can be formed between the adjacent
edges or corners of said terminals, substantially as described.
17. The combination, in a switch, of a connecting plate or device, and a pair of
terminals having contact devices and arranged adjacent to each other side by side,
the end of the contact portion of each terminal at which the connecting device
leaves it being inclined or bevelled away from the other terminal, whereby when
the connecting device breaks the circuit no arc cau be formed between the adjacent
edges or corners of said terminals, and an insulating screen between the terminals,
substantially as described.
18. The combination, in a rotary switch, of a fixed and a rotary member, circuit
terminals side by side, that is in different circles on one member, a contact or con-
necting plate on the other member, adapted to electrically unite said terminals,
said plate having a transverse movement whereby it is adapted to rest squarely on
both terminals substantially as described.
E. H. JOHNSON,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.