Improvements in the Construction of Switches for the Making and Breaking of Circuits Conveying Electric Currents.
Year: 1888

page_text: Date of Application, 23rd Oct., 1888
Complete Specification Left, 20th July, 1889-Accepted, 24th Aug., 1889
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Switches for the Making and
Breaking of Circuits Conveying Electric Currents.
We, CHARLES MARK DORMAN of 24, Brazenose Street, Manchester, in the County
of Lancaster, Electrical Engineer, and REGINALD ARTHUR SMITH of 24, Brazenoso
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 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 Belna Egger, A.D. 1887 No. 5092, and in the specification of John
Henry Holmes A.D. 1887 No. 5648.
Our invention also relates to that class of switch in which the contact pieces are
held together by friction or catches against the force of a spring attached to the base of.
the switch, the force of this spring being utilized for releasing the contact pieces
independent of the movement of the handle.
Our invention consists in adding mechanism connected directly or indirectly to the
handle of the switch, whereby the pressure between the contact pieces is increased
after contact has been made. The same mechanism ensures that the pressure between
the contact pieces is decreased previous to the moment when the force of the spring
or springs tends to move the contact pieces apart. The liability of the failure of the
springs to break contact being thus overcome.
To carry out our invention we attach levers or other suitable connecting pieces to
the handle of the switch and arrange them to gear with screws, cams, wedges, or
other similar contrivances. These are so arranged that after the handle has been
moved into that position in which the springs cause the contact pieces to come
together, further movement of the same handle causes a gripping, clamping, or
wedging action to take place between the said contact pieces. In a like manner when
the switch is used for breaking contact the movement of the handle causes this.
gripping, clamping or wedging action to cease before the springs come into that
position in which they cause the contact pieces to fly apart.
In the case of those switches in which the spring or springs are attached between
the contact piece and the fixed base, the relaxation of pressure between the contact
pieces in breaking contact takes place before the catch or trigger is withdrawn, or, in
those cases where no catches are used, before the contact pieces are allowed to fly
apart under the influence of the springs.
1000
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.

page_text: COMPLETE SPECIFICATION.
Improvements in the Construction, of Switches for the Making and
Breaking of Circuits Conveying Electric Currents:
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 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 Belna Egger, A.D. 1887 No. 5092 and in the Specification of John
Henry Holmes A.D. 1887 No. 5648.
Our Invention also relates to that class of switch, in which the contact pieces are
held together by friction or catches against the force of a spring attached to the base
of the switch, the force of this spring being utilized for releasing the contact pieces.
independent of the movement of the handle, as described in the Specification of John
Henry Holmes, A.D. 1884, No. 3256.
Our invention. consists in adding mechanism connected directly or indirectly to
the handle of the switch, whereby the pressure between the contact pieces is
increased after the contact has been made. The same mechanism ensures that
the pressure, between the contact pieces is decreased previous to the moment when
the force of the spring or springs tends to move the contact pieces apart. The
liability of the failure of the springs to break contact being thus overcome.
To carry out our invention we attach levers or other suitable connecting pièces to
the handle of the switch and arrange them to gear with screws, cams, wedges or other
similar contrivances. These are so arranged that after the handle has been moved'
into that position in which the springs cause the contact pieces to come together
further movement of the same handle causes a gripping clamping or wedging action
to take place between the said contact pieces. In a like manner when the switch
is used for breaking contact the movement of the handle causes this gripping 3
clamping or wedging action to cease before the springs come into that position in
which they cause the contact pieces to fly apart.
In the case of those switches in which the spring, or springs are attached between
the contact arm and the fixed base, the relaxation of pressure between the contact
pieces in breaking contact takes place before the catch or trigger is withdrawn or 4
in those cases where no catches are used before the contact pieces are allowed to fly
apart under the influence of the springs.
Referring to the drawings accompanying this Specification
:-
Fig. 1 is a plan, and Fig. 2, a side elevation of a switch on the principle described
by Belna Egger in his Specification A.D. 1887 No. 5092.-In this switch the 4
handle is not attached rigidly to the contact arm, the motion being transmitted by the
pull of a spring attached at one end to a peg bon the handle, and at the other end
to a peg c attached to a rigid extension of the contact arm d. It will be seen that
when the handle is moved over from against the stop e to the stop f, the spring a
will move over the centre of the switch and pull the contact arm d out of its 5
contact pieces v. v. and so break the circuit.-In à like manner when the handle is
moved back from against the stop ƒ to the stop e, the spring again moves over the

page_text: centre of the switch and causes the contact arm d to fly into the contact pieces v. v.,
and make the electrical circuit. Our improvement consists in fitting the contact
pieces v. v. with right handed screws 9 g., worked by levers gearing in slots in an
extension of the handle as shown, arranged so that the pressure of contact between
the contact-arm and contact pieces is diminished during the time the handle is
moving from e towards f, so that by the time the spring a has moved over the centre
of the switch and the contact-arm is about to fly, the pressure between the contact-
arm and contact pieces is very slight.-Similarly in making contact, after the contact
arm has moved into the contact pieces under the influence of the spring a further
movement of the handle towards e causes the screws g g to grip the contact-arm and
contact pieces firmly together and so make a good electrical contact. When the
switch is closed and making the circuit the spring holds the handle against the
stope and the contact-arm against the contact pieces, and when the switch is open
and breaking the circuit the spring holds the handle against the stop and the
contact arm against the stop h.-It will be seen that in this switch, either the levers
on the screws g g, or the rigid extension of the handle must be made of insulating
material.
Fig. 3 is a plan, and Fig. 4 a sectional elevation of a similar switch, similar
letters referring to similar parts, as in the preceding figures.-In this switch however
the movement of the handle from e towards f in breaking contact causes the left
handed screw which is rigid with the handle, to revolve in the girder k, which is
constrained from revolving, and so releases the pressure between the contact-arm d
and the upper parts of the contact pieces v transmitted through the pegs m_m
attached to the girder k-Similarly in making contact after the contact-arm has
moved on to the contact-pieces under the influence of the spring a further move-
ment of the handle towards e causes a good contact to be made between the contact-
arm and the upper parts of the contact-pieces due to the compression of the
Pegs m
m by the lifting of the girder k. In this switch it will be seen that
either the pegs m m or the girder k must be wholly or partly made of insulating
material.
Fig. 5 is a plan, and Fig. 6 an elevation of a switch on a similar principle to the
preceding ones, but in this case the contact arm d is formed of a number of thin
sheets of hard metal which form contact by pressing on the contact pieces v vas
shown. Similar parts of this Switch are indicated by similar letters to the other
figures.
The centre pin on which the contact arm d freely revolves is furnished at its
upper end with a left handed screw n. The handle is tapped to receive this screw
as shown. It will be seen that a movement of the handle from e towards fin
breaking contact will diminish the pressure between the contact arm and the contact
pieces and thus as in the previous cases allow the switch to break contact quickly and
surely under the action of the spring. Similarly in making contact after the
spring has caused the contact arm to fly on to the contact-pieces a further move-
ment of the handle towards e will grip the laminated contact arm d on to its contact
pieces.
Fig. 7 is a plan and Fig. 8 an elevation of a switch in which the pressure of
contact is increased or diminished by means of wedges and not by screws as in the
preceding cases. Similar parts of this switch are indicated by similar letters to the
other figures. The contact arm d is wedged up against the upper tongues of
the contact pieces vv, by wedges p p actuated by links r r working on pegs on
the handle as shown. It will be seen that a movement of the handle from e towards f
in breaking contact will push the wedges p p which in this case are insulators away
from the centre and so diminish the pressure between the contact arm and the
contact pieces. Similarly in making contact, after the contact arm has entered the
contact pieces under the influence of the spring a further movement of the handle
towards E wedges up the contact arm against the upper parts of the contact pieces
and ensures a good electrical contact.

page_text: Fig. 9 is a plan and Fig. 10 an elevation of a switch similar to that shewn in
Figs. 5 and 6 hut in which the handle takes the form of a central knob. In this
case the knob is fixed to a plate attached by pillars to that part of the handle forming
the nut allowing a clear space for the spring to move backwards and forwards over
the centre of the switch. When it is necessary that the handle should take the
form of a knob the arrangement here shown can be adopted with any of the
switches shown in the other figures the support for the knob being so arranged
that the spring can pass to and fro over the centre on which the contact arm
revolves.
Fig. 11 is a plan and Fig 12 a sectional elevation of a switch in which the spring
is attached between the contact arm and the fixed base. This switch is one of the
type described in John Henry Holmes specification A.D. 1884 No. 3256. It will be
seen that a quick break is obtained by allowing so much play or back-lash between
the handle moved by the operator and the contact arm as to allow the contact arm to
dart away from the contact pieces independent of the speed at which the handle is
moved. In some cases in this type of switch the contact arm is constrained to remain
in contact with the contact pieces by friction only against the pull of the spring.
In others as in that shown in Figs. 11 and 12 a trigger a is arranged to keep the
contact arm d on the contact-pieces after it has been pushed there by the
movement of the handle.. It will be seen that in moving the handle to break contact
the play or backlash between the handle and the contact arm allows the handle to
be moved a certain distance, during which time the pressure between the contact
arm and contact pieces is being lessened before the trigger is released and the
contact arm allowed to fly.
In making contact with the class of switch shown in Fig. 11 and 12 it is not
necessary that the pressure between the contacts be increased after making contact ;
because the pressure of the operator is transmitted directly to the contact arm,
and not through springs as in the preceding figures. The contact arm can
consequently be pushed into contact against considerable pressure, whereas
in switches of the Egger type it is necessary that the pressure of contact be
slight or the pull of the spring very strong at the moment of making contact.
All the figures above described are to a certain extent diagrammatic, the actual
forms of the various parts being not in practice exactly as there drawn.
Fig. 13. is a side elevation of a main switch of the Egger type, fitted with our
improved device, the switch being shown open, Fig. 14. is a plan of the same
switch with circuit closed, and Fig. 15. is a diagram showing the moveable parts of
the switch when closed in full lines, and the same parts when open in dotted lines.
It will be seen that when the handle is moved from the prosition in which it is shown
in full lines in fig. 15 towards the position in which it is shown in dotted lines, that
the right-and-left-handed screw S is caused to revolve in the nuts fixed rigidly to
the girders tt; the pressure between the contact-arms d. d. and the contact pieces v. v
due to the grip of the girders t t is reduced, thus leaving the contact arms, and
with them the girders free to fly into the open position as soon as the spring A has
crossed the centre on which the switch revolves. Similarly when closing circuit, as
soon as the contact arms have been pulled on to the contact pieces by the action of
the springs, a further movement of the handle causes the girders to grip the
contact-arms and contact-pieces firmly together making a good electrical contact.
The action of the Switch is easily understood from an inspection of the figures.
It will be seen that the stops limiting the motion of the handle, shown in the other
diagrams at e and fare here replaced by a single stop w.
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. In switches described and shown in the specification of John Henry Holmes
A D. 1884 No. 3256 the method of connecting directly or indirectly to the bandla

page_text: of the switch mechanism whereby the pressure between the contact pieces is
decreased previous to the moment when the contact-arm is moved or is allowed
to move under the influence of the springs, the liability of the failure of the
springs to break contact being thus overcome, substantially as described and
shown.
2. In switches of the class described and shewn in the Specification of Belna
Egger A.D. 1887 No. 5092 and in the Specification of John Henry Holmes
A.D. 1884 No. 3256 and in the Specification of John Henry Holmes A.D. 1887
No. 5648 the method of connecting directly or indirectly to the handle of the switch
mechanism whereby the pressure between the contact pieces is increased after the
contact arm has made final contact and has ceased to move, the same mechanism
ensuring that the pressure between the contact pieces is decreased previous to the
moment when the contact-arm is moved, or is allowed to move under the influence of
the springs, the liability of the failure of the springs to break contact being thus
overcome, substantially as described and shown.
Dated this 19th day of July 1889.
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.