Make and Break Electric Switches.
Year: 1889

page_text: PROVISIONAL SPECIFICATION.
Quick Make and Break Electric Switches.
We, CHARLES MARK DORMAN of 24, Brazenose Street, Manchester in the County of
Lancaster, Electrical Engineer and REGINALD ARTHUR SMITH of 24, Brazenose Street.
Manchester in the County of Lancaster Electrical Engineer do hereby declare the
nature of this invention to be as follows:-
Our invention relates principally to that class of electric light switch in which the
contact arm is not connected directly to the handle, but through a spring or springs.
It will easily be seen that in this class of switch it is difficult to make a sufficiently
good electrical contact without exerting so great a pressure between the contact pieces
that the force of the spring sometimes fails to draw the contact pieces apart especially
after the switch has been in use for some time and has become dirty.
Examples of the above-mentioned class of switches are described and shown in the
Specification of Belna Egger, A.D. 1887 No. 5092.
In our improved switches we place the centre round which the handle moved by the
operator rotates at a point not coincident with the centre on which the contact arm
moves. This arrangement admits of the same effects being obtained as in the switches
described in the Specification of Belna Egger A.D. 1887, No. 5092, as well as some
improved effects to be hereinafter described.
Referring to the drawing accompanying this Specification it will be seen in Fig. 1
that the handle is pivoted on a centre b in the bracket c, and not on the same centre
as the pivot d about which the contact arm e rotates.
"1
A spiral spring is stretched between a pegg on the contact arm and a peg f
on the handle a..
It will be seen that when the handle is moved over from against the stop / to the
stop the peg f will be moved to f 1, and the tension of the spring will pull the contact
arm e out of the contact pieces connected with the terminal mover into the position
shown in dotted lines against the stop 1; the spring now assuming a position
between 1 and f1.
Similarly in moving the handle from against the stop to the stop 7, the contact
arme is pulled on to the contact piece connected with the terminal m and so electrical
contact is made with the other terminal n.
But if owing to the contacts or pivots having become dirty or from any other cause
it should happen that the tension of the spring is not sufficient to cause the contact
arm to move, the switch is rendered ineffective.
To overcome this difficulty we arrange pegs and s on the handle a in such a posi-
tion that when the handle is being moved over from one side to the other, and when
the spring has reached such a position that it is exerting a turning moment on the
contact arme, these pegs push up against the contact arm and overcome any tendency
that the contact arm may have to remain behind, thus ensuring a positive action of the
switch, from the fact that the pressure of the hand of the operator is transmitted
directly to the contact arm, and not through the spring alone as is the present practice
in switches of this description.
We are able to accomplish this object because in the type of switch of which Fig. 1 is
diagrammatic those parts both of the contact arm and of the handle which are
situated between the respective centres round which they rotate always move approxi-
mately in the same direction, that is from right to left or from left to right as shown
in. the drawing, and not in opposite directions as the whole of the handle and of the
contact arm move in switches of the type described in Specification of Belna Egger,
A.D. 1887. No. 5092.
It will also be seen that in this type of switch it is not absolutely essential that the

page_text: spring shall move across over or under the centre on which the contact arm is
pivotted.
We do not confine ourselves to the exact form of switch shown in the drawing,
sometimes using a central turning knob instead of a lever handle, and sometimes
arranging the handle to move in a plane at right angles to the base plate, and not in
a plane parallel with it as there shown.
Dated this 9th day of December 1880
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.
COMPLETE SPECIFICATION.
Quick Make and Break Electric Switches.
We CHARLES MARK DORMAN of 24 Brazenose Street Manchester in the County of
Lancaster Electrical Engineer and REGINALD ARTHUR SMITHI of 24 Brazenose Street
Manchester in the County of Lancaster 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:-
Our invention relates principally to that class of electric light switches in which
the contact arm is not connected directly to the handle but through a spring or
springs.
It will easily be seen that in this class of switch it is difficult to make a sufficiently
good electrical contact without exerting so great a pressure between the contact
pieces that the force of the spring sometimes fails to draw the contact pieces
apart especially after the switch has been in use for some time and has become
dirty.
Examples of the above mentioned class of switches are described and shown in the
Specification of Belua Egger A.D. 1887 No. 5092.
In our improved switches we generally place the centre round which the handle
moved by the operator rotates at a point not coincident with the centre on which the
contact arm moves. This arrangement admits of the same effects being obtained as
in switches described in the Specification of Belna Egger A.D. 1887 No. 5092 as well
as some improved effects to be hereinafter described.
Referring to the drawing accompanying our Provisional Specification it will be seen
in Fig. 1 that the handle is pivoted on a centre b in the bracket c,and not on the same
centre as the pivot d about which the contact arm e rotates. A spiral spring
is stretched between a peg on the contact arm e and a peg f on the handle a.
It will be seen that when the handle is moved over from against the stop to the
stop the peg will be moved to f 1 and the tension of the spring will pull the contact
arm out of the contact pieces connected with the terminal m, over into the posi-
tion shown in dotted lines against the stop 7; the spring now assuming a position
between 1 and f 1.
Similarly in moving the handle from against the stop to the stop the contact
arm e is pulled on to the contact piece connected with the terminal m and so
electrical contact is made with the other terminal m.
But if owing to the contacts or pivots having become dirty or from any other cause
it should happen that the tension of the spring is not sufficient to cause the contact arm
to move, the switch is rendered ineffective.
To overcome this difficulty we arrange pegs p ands on the handle in such a
position that when the handle is being moved over from one side to the other, and
when the spring has reached such a position that it is exerting a turning moment on
the contact arm e, these pegs push up against the contact arm and overcome any
tendency that the contact arm may have to remain behind, thus ensuring a positive
action of the switch, from the fact that the pressure of the hand of the operator is
transmitted directly to the contact arm, and not through the spring alone as is the
present practice in switches of this description.
We are able to accomplish this object because in the type of switch' of which Fig. 1

page_text: is diagrammatic those parts both of the contact arm and of the handle which are
situated between the respective centres round which they rotate always move approxi-
mately in the same direction that is from right to left or from left to right as shewn
in Fig. 1, and not in opposite directions as the whole of the handle and of the
contact arm move in switches of the type described in the Specification of Belna Egger
A.D. 1887 No. 5092.
It will also be seen that in this type of switch it is not absolutely essential that the
spring shall move across over or under the centre on which the contact arm. is pivoted,
although we find in practice that a better effect is produced when the peg is moved
further from the centre till the distance between 6 and fis as great as or greater than
the distance between and d.
In some cases it is found in practice to be inconvenient to attach the handle grasped
by the operator rigidly to the piece carrying the peg f to which one end of the
spring is attached when this is the case we mount the handle on any other con-
venient centre and gear it to the piece carrying the peg f by means of teeth, cams
and jaws, links or any of the ordinary contrivances well known to mechanics.
Referring to the drawings accompanying this Specification Fig. 2 shows a switch
in which the handle is pivoted above the same centre as the contact
arm and
geared to the piece carrying the spring peg f by teeth as shown. It will be seen
in the case of switches with a geared handle like Fig. 2 that those portions of
both geared quadrants which are situated between the relative centres 6 and
round which they rotate always move approximately in the same direction, that is
from right to left or from left to right as shown in Fig. 2, and that this direction is
approximately the same as that of the contact arm c. Hence it is obvious that we may
either place our pushing and pulling pegs p and son the quadrant which moves on
the centre as shown in Fig. 2, or if more convenient on the other quadrant rigidly
attached to the handle a.
Fig. 3 shows a switch in which the pushing and pulling pegs are rigidly attached
to a geared handle. In this switch the pegs ands and the gearing peg are rigidly
attached to a handle not shown in the drawing. This handle, since the spring in this
switch passes across the centre d, is mounted on a bracket, not shown, after the style
of the handle in Fig. 1.
The office of the intermediate geared part to which the peg f is attached is to
carry the spring over into such a position that it exerts a turning moment on the
contact arme and causes it to fly, any tendency of the contact arm a to stick being
then overcome by the positive push of the pegs ? or on the handle.
The different parts of the switch can if desired be so arranged that one peg only is
necessary, in fact in Fig. 3 either ? or s may be dispensed with. The pegs or pro-
jections may if more convenient be placed on the contact arm instead of on the handle,
so long as they are made to gear with the handle at the right time.
The switch shown in Fig. 3 is a double-break one the terminals being at m and n.
The switches shown in the drawing are merely diagrammatic. We do not confine
ourselves to the exact forms shown in the drawings, sometimes using a turning knob
instead of a lever handle, and sometimes arranging the handle to move in a plane at
right angles to the base-plate, and not in a plane parallel with it as there shown. We
do not always use a tension spring of the form shown; any form of spring, flat, spiral
or compression, can be used so long as it is arranged to exert the correct turning
moment on the contact arm at the proper instant.
Having thus particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is-
In switches of the quick make and break class described and shown in the Specifi-
cation of Belna Egger, A.D. 1887 No. 5092 the method of attaching either directly to
the handle moved by the operator or to mechanism suitably geared thereto one or
more parts so arranged as to positively transmit the motion of the handle to the

page_text: contact lever in either making or breaking contact and so render the switch effective if
from any reason the force of the spring or springs is insufficient to overcome the
friction of the switch, substantially as described and shown in the drawings.
Dated this 9th day of September 1890.
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.