Improvements in Electric Switches.
Year: 1892

page_text: Date of Application, 11th Feb., 1892
Complete Specification Left, 11th Nov., 1892-Accepted, 17th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Electric Switches.
I, ALFRED LYSTER SHEPARD, 8 West Kensington Gardens in the County of
Middlesex, Electrical Engineer do hereby declare the nature of this invention to be
as follows:-
My invention relates to electric switches and has for its object the production of
switches which shall be simple in design mechanically strong and moreover be very
efficient and possess the desirable quality of very quickly breaking and in some
cases also making the circuit so as to prevent the occurrence of sparking and of
accidental bad contacts.
An important feature of my invention consists in arranging that the bar or bridge
piece which makes contact shall be operated by means of a screwed spindle.
Another important feature of my invention consists in the combination with the
screwed spiudle or with a nut on the said spindle of a spring or springs for effecting
a quick break or quick make and break.
One method of carrying my invention into practice by which I can make a
convenient form of double pole switch is as follows:-The contact pieces which are
joined by solder or otherwise to the ends of the four line wires are secured to the
corners of a suitable base block which may be of slate or other suitable material.
I mount two bars or bridge pieces of brass or other metal on a common screwed
spindle; one of the said bridge pieces serves to connect the contact pieces at one
end of the base and the other of the said bridge pieces connects the contact pieces at
the other end of the base. The screwed spindle is mounted in bearings at each end
of the base. The bars or bridge pieces are provided with bosses in their centres
through which suitable sized holes are drilled the said holes are lined inside with
vulcanised fibre or other suitable non-conductor, and end plates of similar non-
conducting material are secured on each face of the said bosses..
In this pattern I prefer to have one end of the spindle screwed with a left- and
the other with a right-handed screw thread so that the bars or bridge pieces will
travel in opposite directions. Inside the boss of each bar I provide a nut tapped
to fit one part of the screw, thus one nut will be a left- the other a right-handed
nut. The nuts are not rigidly secured to their respective bars or bridge pieces but
are adapted to slide axially therein but not to rotate relatively thereto and the
bridge pieces themselves are maintained parallel to the base by suitable guides.
The screwed spindle is fitted to rotate in its bearings without appreciable end play.
It will be seen that on turning the spindle the nuts will be moved until they.
encounter the aforesaid end plates of the bridge pieces. On further continuing the
rotation of the spindle, the bridge pieces themselves will be moved the one in one
direction and the other in the opposite direction thus either making or breaking the
connections at both ends of the base. When I desire to secure a quick break I.
arrange between the nut and the bridge piece a spring which may be spiral or of
other suitable form. The said spring is deformed when the screwed spindle is
rotated and tends to move the bridge piece away from the contacts.
I prefer
however that the spring shall not be sufficiently strong to move the bridge piece
when deformed through the limit permissable in the apparatus until the electrical
connection between the bridge piece and the contact pieces is nearly broken. At
this point the spring acts to break the connections very rapidly.
It is obvious that by suitably arranging springs between the nuts and both sides
of the bridge pieces I can construct a switch which will make as well as break the
circuit anikl

page_text: It is obvious that I can make a convenient single pole double break switch on the
principle above described. In a modification of quick break switch I make the
screwed spindle with a certain amount of end play, that is to say the spindle is
capable of moving axially a distance equal to the break required. In this form I
generally use only one bar or bridge piece and the nut is firmly secured thereto.
The spring for securing a quick break or make in this case is arranged so as
to exert an axial force on the spindle tending to keep the bar or bridge piece away
from in the case of a quick break switch, or close against the contact pieces in the
case of a quick make switch. This can be done with a spiral spring for instance by
arranging the spring between one of the bearings of the spindle and a washer or
projection secured to the same. In the case of a switch adapted for a quick break
the bar or bridge piece being as before held tight by the contact pieces when
contact is made, is not moved at first when the handle is turned to break the circuit
the spindle merely screwing through the nut in the said bar and thereby straining
the spring until it is stopped by the bearing, the bar is then moved along the
contacts until it is sufficiently nearly released for the spring to overcome the grip of
the contact pieces, thereby forcing the bar away from the said contacts and breaking
the circuit.
In a switch adapted for making the circuit quickly I provide if necessary a catch
or detent actuated either by the movement of the nut or screwed spindle as the case
may be which prevents the bar or bridge piece making contact until the spring has
been strained sufficiently to enable the contact to be made quickly as desired.
I can transform any single pole switch of the design hereinbefore mentioned into
a double pole switch in a very simple manner by making the bar of vulcanized
fibre or other non-conductor and each contact piece in two parts insulated from
each other, the ends of the bar being adapted to make contact between the two
separate parts of each contact-piece.
Although I have mentioned several methods of carrying out my invention I do
not limit myself to those forms of switch hereinbefore described as it is evident
that there are many other forms of switches to which I can apply my invention
without departing from the nature thereof.
Dated this 11th day of February 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electric Switches.
1, ALFRED LYSTER SHEPARD, of 8 West Kensington Gardens, in the County
of Middlesex, Electrical 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 :-
My invention relates to electric switches and has for its object the production of
switches which shall be simple in design, mechanically strong, and moreover be
very efficient and possess the desirable quality of very quickly breaking and in
some cases also making, the circuit so as to prevent the occurrence of sparking and
of accidental bad contacts.
An important feature of my invention consists in arranging that the bar or
bridge piece of the switch which makes contact shall be operated by means of a
screwed spindle.
Another important feature of my invention consists in the combination with the
screwed spindle or with a nut on the said spindle of a spring or springs for effecting
a quick break or quick make and break.

page_text: In order that my invention may be more easily understood I will now proceed to
describe the same with reference to the accompanying drawings in which,
Figure 1 is a front view of a switch constructed in accordance with my invention
the circuit being broken.
Figure 2 is a side view of the same partly in section.
Figure 3 is a similar view to Figure 2 the bar or bridge piece of the switch
being in a different position.
The switch shewn in the figures is what is known as a "double-pole" switch,
that is to say, it makes and breaks the circuit in two places, usually in the positive
lead and in the negative or return lead.
A is the base of the switch which is made of slate or other suitable material.
B, B', are contact blocks of suitable form secured to the base by suitable screws
and to which the ends of one lead, the positive for instance, are electrically
connected. C, C¹ are contact blocks to which the ends of the other lead are joined.
D is a bridge piece which carries a suitable contact piece D¹, D', at each end.
One of the contact pieces D' is adapted to electrically connect the contacts B
and B, the other D is adapted to connect the contacts C and C. The contact
pieces D', D' are preferably made of a number of plates of suitable metal as shewn
and are firmly mounted on the extremities of the non-conducting_bridge piece D
which may be of vulcanized fibre or other suitable insulator. E is a screwed
spindle supported in a bearing F which is hereinafter more particularly described.
The screwed portion E¹ of the spindle E is made with preferably multiple screw-
threads and is adapted to engage with a corresponding nut D³ secured in or forming
part of the bridge piece D. I provide a collar E' attached to the end of the spindle
to prevent the latter from being withdrawn altogether from the bridge piece. The
spindle is moreover provided with other collars E³, E', preferably made in one
picce with itself.
The bearing F is provided with an end plate F¹ and a screw-threaded recess F.
G is a spiral spring which is in compression between the end plate F¹ of the bearing
and the collar E on the spindle.
The end E of the spindle is squared so as to fit a square hole H' in the boss
of the handle H. The spindle is thus rendered capable of moving axially but
not of rotating relatively to the handle. The cylindrical portion of the handle H
is provided with a collar H and is thereby rotatably secured in the recess F³ by
means of the split nut F as shewn.
A suitable stop A' formed of insulating material is secured to the base of the
switch for a purpose hereinafter described.
The operation of the switch is as follows:
When the switch is in the position shewn in Figures 1 and 2 of the drawings the
circuit is broken. If the handle be turned, thereby rotating the spindle the screwed
portion E of the latter causes the bridge piece D to approach nearer to the contact
pieces B, B, C, C¹ and finally to make the circuit by means of the contact
pieces D¹, D³. The collar E presses against the end of the bearing F and
prevents any axial movement of the spindle while the contact is being made.
When the circuit is to be broken, the handle is turned in the opposite direction ;
whereupon the bridge piece D being clamped tightly by the contacts forces the
screwed spindle to move axially through the bridge piece thereby compressing
the spring G. The spindle having moved as far as the spring G will allow
or until the collar E' comes against the stop A' as shewn in Figure 3 it begins to
move the bridge piece towards the bearing Funtil the contact is nearly broken when
the spring acts to complete the operation and very rapidly breaks the circuit. The
bridge piece is then in the position shewn in Figure 1.
In another method of carrying out my invention I prevent the screwed spindle
from having any axial movement, while mounting the nut in the bar or bridge piece
in such manner that it can slide therein, and connecting it thereto by springs to
provide for a rapid make or break. A convenient form of double pole switch

page_text: constructed according to this modification is as follows: The contact pieces which
are joined by solder or otherwise to the ends of the four line wires, are secured to
the corners of a suitable base block. I mount two bars or bridge pieces of brass
or other metal on a common screwed spindle one of the said bridge pieces serving
to connect the contact pieces at one end of the base and the other of the said
bridge pieces to connect the contact pieces at the other end of the base. The
screwed spindle is mounted so as to be capable of turning but not sliding in
bearings at each end of the base. The bars or bridge pieces are provided with
bosses at their centres through which suitable sized holes are drilled. The said
holes are lined inside with vulcanized fibre or other suitable non-conductor, and end
plates of similar non-conducting material are secured on each face of the said
bosses.
In this pattern I prefer to have one end of the spindle screwed with a left- and
the other with a right-handed screw thread so that the bars or bridge pieces will
travel in opposite directions when the spindle is rotated. Inside the boss of each
bar I provide a nut tapped to fit one part of the screw, thus one nut will be a left-
the other a right-handed nut. The nuts are not rigidly secured to their respective
bars or bridge pieces but are adapted to slide axially therein but not to rotate
relatively thereto and the bridge pieces themselves are maintained parallel to the
base by suitable guides. It will be seen that on turning the spindle the nuts will
be moved until they encounter the aforesaid end plates of the bridge pieces. On
further continuing the rotation of the spindle, the bridge pieces themselves will be
moved the one in one direction and the other in the opposite direction thus either
making or breaking the connections at both ends of the base. When I desire to
secure a quick break I arrange between the nut and the bridge piece a spring
which may be spiral or of other suitable form. The said spring is deformed when
the screwed spindle is rotated and tends to move the bridge piece away from the
contacts. I prefer however that the spring shall not be sufficiently strong
to move the bridge piece when deformed through the limit permissible in the
apparatus until the electrical connection between the bridge piece and the contact
pieces is nearly broken. At this point the spring acts to break the connections
very rapidly.
It is obvious that by suitably arranging springs between the nuts and both sides
of the bridge pieces I can construct a switch which will make as well as break the
circuit quickly.
It is obvious that I can make a convenient. single pole double break switch on
the principle above described.
In a switch adapted for making the circuit quickly I provide if necessary a catch
or detent actuated either by the movement of the nut or screwed spindle as the
case may be which prevents the bar or bridge piece making contact until the
spring has been strained sufficiently to enable the contact to be made quickly as
desired.
Although I have herein described a spiral spring as being convenient for use in
my improved switch, I wish it understood that I may use springs of other forms
which may be found suitable for the purpose.
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 a switch, the combination with a screw threaded spindle for moving the bar
or bridge piece, of a spring to secure a rapid make or break, substantially as
described.
2. A switch for either quickly making or quickly breaking an electrical circuit
having a bar or bridge piece operated by an axially movable screwed spindle the
movement of which spindle is controlled by a spring, substantially as described, for
the purpose specified.

page_text: 3. The modification of the switch claimed in the last preceding claim, wherein
the screwed spindle is not axially movable and engages a nut which is connected
to the bar or bridge piece by a spring, substantially as, and for the purpose,
specified.
4. A switch constructed substantially as described with reference to the accom-
panying drawings, for the purpose specified.
Dated this 10th day of November 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.