Improvements in Electrical Switches and other Fittings.
Year: 1892

page_text: Date of Application, 1st Dece, 1892
Complete Specification Left, 1st Sept.. 1893-Accepted. 7th Oct.. 1893
PROVISIONAL SPECIFICATION.
Improvements in Electrical Switches and other Fittings.
I, GUSTAV BINSWANGER, of 71 Queen Victoria Street, in the City and County
of London, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
-
My invention relates to improvements in the construction of that form of electric
switches in which advantage is taken of the lost motion or backlash between the
actuating handle or key of the switch and the moving contact bar to allow of
the stored energy of a spring acting on the bar suddenly releasing it from contact
with the contact plates after the handle or key has moved the said bar a certain
distance and my improvements consist first in a new method of attaching the key
or handle to the moving bar in such a manner that the said key or handle may
be readily and quickly detached in order to allow the cover of the switch to be
taken off or put on which method of attachment may also serve to retain the.
cover in position. This method of attachment is also applicable to the covers
of ceiling roses, cut outs, and other electrical fittings, the covers whereof are
required to be readily removed and replaced.
Secondly my improvements relate to the cam for operating the moving contact
bar and to the spring actuating the same.
Now according to this invention I attach to a suitable base (preferably circular)
of porcelain or other suitable material a sector shaped metal plate in the centre
of which is attached in such a manner as to be capable of rotation on its axis
an upright stem.
In this upright stem immediately above the base is firmly fixed a cross pin which
engages with a slot in a diamond shaped cam attached to or formed integral with
the under surface of the moving contact bar. This slot is wide enough to allow
the necessary amount of "backlash" to ensure the contact bar being suddenly
released from the contact plates under the action of a spring acting on the cam
when the handle or key has been turned sufficiently to enable the said spring to
act advantageously on the said cam.
The spring which is preferably inade from steel wire is coiled once or twice
round an upright pin near the outer edge of the baseplate the ends of the wire
forming arms which press one on each side of the cam and so rotate the contact bar.
The upright stem is drilled axially and a screw thread formed therein to receive
a screw passing through the key or handle.
The key or handle has a hole through it enlarged at the lower part to admit the
upright stem a second cross pin in which engages with a slot in the key or handle.
Or the upper part of the stem may be square or any other suitable shape and the
hole in the key be made to fit the same.
The hole at the top of the key is countersunk to admit the head of the screw
which secures the key to the stem.
The contact bar and the plate supporting it form with a suitable terminal one
pole of the switch and for the other pole I provide a suitable contact plate with
its terminal fixed at one end to the insulating base so shaped or bent that the
free end thereof stands over but clear of the other plate.
When the key is turned in one direction the contact bar is forced between
the two contact plates and closes the circuit at the same time the cam turning
with the bar opens the two arms of the spring until they rest on the corners
of the cam and hold the contact bar from moving. On turning the key or handle
in the opposite direction, the upright stem turns with it as soon as the cross pin
engages with the cam a very slight further movement of the key moves the cam

page_text: past the dead point when the spring acting upon the same causes the contact bar
to rotate rapidly and suddenly break the circuit the break being independent of
any further movement of the key.
The backlash" being allowed in the cam the key can be rigidly secured to the
stem thereby avoiding the breakage of porcelain keys so frequent in switches where
the "backlash" is between the stem and the key.
In some cases the key may be formed with a flange on the part which stands
immediately over the cover thereby retaining the cover in place and rendering the
switch practically dust proof.
In order to prevent the screw securing the key to the stem or the screws
attaching the covers to cut-outs, ceiling roses and other fittings from being lost
I secure them as follows:-
The screws which have formed thereon shoulders a little longer than the
thickness of that portion of the key or cover through which they pass are placed in
position a washer is then placed over them and the edge of the shoulder turned over
the washer or a small nut is placed on the screw and run down to the shoulder thus
securing the screw in its place. For ceiling roses, cut-outs and the like I prefer to
use milled headed screws.
Dated this 29th day of November 1892
+
FREDK. WALKER,
11, Furnival Street, Holborn, London, E.C., Agent for the Applicant.
+
COMPLETE SPECIFICATION.
Improvements in Electrical Switches and other Fittings.
I, GUSTAV BINSWANGER of 71 Queen Victoria Street in the City and County
of London 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 improvements in the construction of that form of electric
switches in which advantage is taken of the lost motion or "backlash" between the
actuating handle or key of the switch, and the moving contact bar, to allow of the
stored energy of a spring acting on the bar suddenly releasing it from contact
with the contact plates, after the said handle or key has moved the bar a certain
distance, and my said improvements consist first in a new method of attaching the
key or handle to the contact bar so that said key or handle may be readily
detached or replaced, so that the cover of the switch may be removed when
desired, and said method of attachment may also include the retention of the
cover in its place, and is in this respect applicable to the covers of ceiling roses,
cut-outs, and other electrical fittings.
Secondly my improvements relate to the cam for operating the moving bar and
to the spring actuating same.
In order that my said invention may be clearly understood, I have appended the
accompanying sheet of drawings in which Figure 1 represents a plan view of a
switch in which the cover and key are removed, and Figure 2 is a sectional
elevation of the same, with the contact bar, spring and plates removed, shewing the
manner of attaching the handle or key. Figure 3 is an elevation of the handle or
key, as seen at right angles to the position shewn by Figure 2. Figure 4 shews
the contact bar detached plan and elevation. Figure 5 is a sectional elevation
shewing the method of securing the covers of ceiling roses, cut-outs, and like
fittings. Similar letters of reference indicate corresponding parts in the several
views, where practicable.
In carrying my invention into effect, I attach a sector shaped metal plate a to a
porcelain or other base A Figures I and II, in the centre of which an upright
stem is fitted so that it may freely rotate. Immediately above the base a pin c is

page_text: firmly fixed to the stem b, which engages with a slot d Figure 4, in a diamond
shaped cam e fixed to the under side of the contact bar B, which, but for the pin c
fitting in said slot d, is perfectly loose upon said stem. The slot d is made of
sufficient width to allow of the necessary amount of backlash so that the contact
bar B may be suddenly released from the contact plates C, by reason of the action
of a spring D, preferably made of steel wire, and coiled once or twice round a
pin, the ends forming arms which embrace the came when the switch is in the
"off" position as indicated by the dotted lines Figure 1, and is in extreme tension
when the switch is "on" as represented by said view. E and E' are terminals,
and F is an ordinary fusible cut out, forming no part of my invention. It will be
seen that the backlash is taken up by the pin c in the slot d to put the contact.
bar B into contact with the plates C, the spring D being thus placed in tension by
the cam e.
When the key or handle H is turned in the opposite direction, the
backlash is again taken up, but the slightest pressure of the pin against the
side of the slot releases the cam from the spring, the action of which sharply
removes the bar B from its contact with C without causing sparking or "arcing"
in breaking the circuit. In order to attach the key or handle H, the stem b
is drilled axially, and a screw thread formed therein to receive a screw g, the
head of which is let into a recess in said key or handle, and which is
prevented from being separated therefrom by means of a collar or washer i,
over which said screw is rivetted or burred, so that it may turn freely, but
always remains in position within H. Said washer is let into a recess in the
lower part of the key or handle H, which is formed with a slot or groove j,
shewn more particularly by the end elevation Figure III. The. upright stem b
is drilled to admit a transverse pin k, which engages with the slot in the key
or handle H when this is placed in position, and the screw g screwed into the
stem . A collar or shoulder I may be formed upon or attached to the key or
handle H, which may be arranged to work underneath the cover I as shewn by
Figure 2, in which case said cover is screwed upon the base A, or as an alternative,
the collar or shoulder / may be above said cover I, and serve to hold the same in
し
position.
The especial advantages of the switch according to my invention are in that
directly the cam e is moved past the dead point, the spring D causes contact to be
instantly broken, independently of any further movement of the key or handle H,
and also that the porcelain or like keys are not so liable to be broken as when the
"backlash" exists between said key and the contacts directly, and further, the
flange, collar or shoulder on the key or handle H practically keeps the interior of
the switch dustproof whether this be above or underneath the cover I.
In attaching the covers of ceiling roses, cut outs, and other electrical fittings,
I prefer to use a nut J, Figure 5, which is preferably milled. A portion of the
shank thereof is turned down to pass through the cover I, the shoulder resting
upon the outer surface thereof. A washer m passes over said turned down portion
on the under side of I, and the projecting edge is burred or rivetted over, so that
the nut J is free to turn but cannot be removed from the cover I. A screw n, the
head of which is recessed into the base A, is secured by a nut o or equivalent, and
projects upwards so that the screwed end may engage with the nut J, and so secure
the cover in position, and ensure its ready removal and replacement when
necessary without danger of losing any part of the attachment.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
First. In an electrical switch, the combination of a slotted or grooved cam
attached to a contact bar, engaging with a spring, with a stem carrying a pin
working in said slot or groove, and a grooved key or handle fitting upon a second
pin in said stem, and secured thereto by a screw, substantially as herein described
and shewn by the appended drawings.

page_text: Second. In an electric switch, ceiling rose, cut-out, or similar electric fitting, the
employment of a shouldered nut passing through the cover, and not removeable
therefrom, substantially as herein described with reference to Figure 5 of the
appended drawings.
Third. In an electric switch, ceiling rose, cut out, or similar electric fitting, the
employment of a screw passing through the key, handle, or cover, and not
removeable therefrom, substantially as herein described with reference to the
drawings.
Fourth. In an electric switch the method of and means for taking advantage of
the "back lash" to promote a rapid break, substantially as herein described and
shewn.
Fifth. In an electric switch the employment of a slotted key or handle, with a
flange, shoulder or collar in combination with a pin upon the central stem, and a
cover, substantially as herein described and shewn by the drawings.
Dated this 28th day of August 1893.
FREDK. WALKER,
11, Furnival Street, London, E.C., Agent for the Applicant.