Improvements in and in the Manufacture of Electrical Switches.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in and in the Manufacture of Electrical Switches.
I, AMANDUS METZGER, of 901 State Street, Schenectady, N.Y., U.S.A.,
Electrician, 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 :-
This my invention has reference to certain new and useful improvements in
electrical switches and in the manufacture thereof.
Owing to the manner in which the metal composing the various parts of my
improved switch is distributed and arranged, in a switch of given capacity, by my
method it is possible to produce an appliance which will fulfill its object
satisfactorily and effectively and enable a saving of 20 to 50 per cent. to be
effected in the weight of metal employed, and a saving in the cost of labour of
10 to 25 per cent.
The fact that all parts are made in presses and dies presents a further advantage
in that each part is completely interchangeable so that there are increased facilities
for replacing such parts that are in the ordinary use of the switch are gradually
deteriorated by the action and effect of the current. Switches can be produced
more rapidly from stampings than from castings on account of the lessened labour
for finishing up. Hitherto switches of the design I am about to describe have been
made up from a combination of two metals, brass and copper; brass being used in
the position where solidity and mass are required and copper where electrical
conductivity is the first desideratum. A contact clip for instance has usually
consisted of a cast brass base piece in which is secured two strips or plates of
copper; these copper plates being cut from a sheet or strip and arranged in two
parallel planes at the proper distance apart so that both the inside faces would
make efficient contact with the brass or copper blade inserted between them.
Disregarding the expenditure of labour necessitated by this construction it is
apparent that its electrical design is not perfect. The copper clip pieces are
usually let into slots cut into the base piece and are soldered or rivetted into
position. When therefore connection is made with the line circuit the current
must first pass through the brass base and then through this soldered or rivetted
joint before it enters the blade in order to pass on to the second line terminal.
Tests and experience have shewn that any break in the continuity of a circuit is to
be avoided; each junction meaning an increased loss in energy owing to increased
resistance. This in some measure accounts for the increase in temperature which
occurs in switches at present in commercial use. Calculation will shew that in
time the loss of energy occasioned by a number of switches in a circuit amounts to
a considerable item.
In switches of my construction, the above referred-to difficulties and disadvantages
are minimized by making the contact clip in one piece and from one metal, the
disposition of the parts is also such that each switch represents the simplest
arrangement that can be devised for completing or severing an electrical circuit.
I now proceed to describe my said invention, reference being had to the
accompanying drawings, and to, the figures and letters of reference marked
thereon.
Fig. 1. shews the tool (consisting of two parts, the punch Y and the die Z.) by
which the blank A is cut out of the sheet metal. It will be noted that this
blank A is of such shape, that it provides for all the necessary or desirable features
that it should contain. The projections a will form the parallel faces between
which the contact blade D (Figs. 11 Sheet 1, & 12, Sheet 4) will slide. The small

page_text: projections will form the ears to be raised on either side of the binding screw by
which the line wire will make efficient contact with the clip. will be utilized to
strengthen the base of the clip, at that part where the binding screw passes through
it, as hereinafter described. The blank A is intended to form the pivot clip,
i.e. the one in which the blade is mounted above the switch base. The blank B
(Fig. 2., Sheet 2.) is designed to form the receiving contact clip of the switch;
i.e. the clip into which the blade D must be inserted in order to close the circuit.
This blank has an additional projection d which forms a stop upon which the blade
will rest when it is forced between the contact faces a (Fig. 12). This projection
has an important function, inasmuch as it ensures the correct position of the blade
when in the clip.
Fig. 3, (Sheet 2) shews the bevelling tool, which comprises two parts X and W;
X being the punch and W the matrix into which the blank is forced. The effect
of forcing a blank into the matrix results in obtaining the bevelled edges e, upon
the projections forming the sides of the clip, so that when the stamping is formed
up ready to receive the blade (the alignment being fairly correct,) the blades will
pass in between the sides of the jaw of the clip without sticking or striking upon
the upper edges of the clip. A secondary use of this tool is the planishing or
straightening of the contact faces a.
The next process is to punch the holes fin the blank (Fig. 2) so that there is a
means of securing the clip to the switch base. The tools for this operation are
shewn in Fig. 4; V being the punch and T the die; it will be noted that the die is
fitted with a guide frame as this is found to be a convenience for holding the
blank in position, so that the holes can be punched in the exact position required.
The punching tools required for the pivot-hole g (Fig. 1.) in the blank used to
make the pivot clip are substantially the same as those last-referred-to and shewn
in Fig. 4.
It is obvious, that if preferred, all the holes that it is necessary to make in a blank,
could be punched by one operation; but for the purpose of making the description
as clear as possible, I have considered it best to describe each process separately
as above.
The next process is to double the strengthening plate e (Figs. 1 and 2) over on
the body of the blanks A and B, as clearly shewn in Fig. 5. (Sheet 2). This is
effected by a tool comprising a forming punch S and a receiving die R. This die
is also fitted with a guide for receiving the blank. When the punch is forced into
the well it will obviously turn up the end projecting piece c of the blank, so that
it makes an angle with the body of the blank equal to that of the wedge-shaped
point of the punch S. The projection c can now be hammered or otherwise
flattened down upon the body of the blank.
The blank is now in shape to undergo the chief forming operation. The tools
for accomplishing this are shewn in Fig. 6. (Sheet 3.) and comprise a punch P and
a matrix or forming die Q. The die is as usual, provided with a guide-plate.
When the blank (shewn in Fig. 5., Sheet 2.), is laid in the die and compressed by
the punch, it is forced into the well, which results in having all the projections
thrown up perpendicularly to the base. The projections a will now form the
sides of the clip; the projections b will form the ears (Fig. 12. Sheet 4) on either
side of the binding screw hole, and the projection d will form the stop for the
switch blade. It is also evident that this operation might complete the clip ready
for mounting upon the base. This would mean that the sides had been thrown up
at such a distance apart that they will make contact with the sides of the contact
blade. I prefer, however, to raise them up as shewn in Fig. 6. (Sheet 3.) that is,
with the sides at a further distance apart than required by the thickness of the
blade, and continue the forming operation still further, so as to form a clip of the
shape shewn (Fig. 7. Sbeet 3.) and indicated by the letters G and H; & being
the pivot clip and H the switch clip. This operation is accomplished by using a
more complicated forming tool, shewn in Figs. 7 and 8, Sheets 3 and 4. This tool
consists of a forming punch N, a mandril MI and a lower matrix O.
It will be

page_text: of the
It is.
noted that the face of the punch N is cut away so as to form an approximately
semi-circular aperture m whilst the similar receiving block fitted in the matrix O.
is provided with an equal aperture n. Above this aperture there is pivotally
mounted a sliding mandril P. Into the jaw of the mandril the tongue
mandril M can be forced so that a practically solid forming block results.
necessary to make this forming block a composite one so as to provide for the
projection d on the contact clip. The sliding mandril working on the pivot r
in the guides s, is kept ordinarily above the lower receiving block by means of a
spring-pin (arranged at the back thereof and not shewn) so that the blank can be
readily inserted in position as shewn in Fig. 8. The blank as shewn in Fig. 6.
(Sheet 3) is placed around the mandril p and the detached mandril M is inserted
between the jaws of the sliding mandril and the tool is ready for work; this-
condition of affairs being shewn in Fig. 8. (Sheet 4). It is evident that when the
punch N is compressed upon the die O the mandril p is forced downwards into the
aperturen and a stamping results of the shape shewn in the figure on the right
(Fig. 8.), and the clip is formed completely. The distance between the contact.
faces of the clip is regulated by the thickness of the tongue t of the mandril M.
For some switches such as the larger sizes, it is desirable to strengthen the whole.
of the base of the contact clip; and for this purpose I have found it desirable to
use an auxiliary stamping / (Fig. 9., Sheet 1). This is produced by punching and
forming processes similar to those already described. This piece is placed under
the clip, between it and the base, or inside the clip and screwed down onto the
switch-base with the body of the clip between it and the base.
The perfectly formed, and perhaps, additionally strengthened clips required for
the switch, can now be mounted and correctly aligned on the porcelain, slate, wood
or other base which is provided for them.
The contact-blade (Figs. 10, Sheet 1, and 12, Sheet 4) consists of a straight bar
or strip of metal D, pierced at one end with a hole through which the pivot-pin y.
of the pivot-clip is passed. The pivot mounting is for the purpose of supporting
the blade in such manner that it can be thrown into or out of the contact clip..
When the blade is in the contact clip, a circuit for the current is completed between
the two clips through the length of the blade, and hence, by swinging the blade-
away from the contact clip, the circuit can be broken. The blade can either be-
cut from strip metal, such as brass, copper or any other metal of high conductivity;
strip metal being readily obtained from metal merchants, or it can be punched or
stamped from a sheet of metal. For some uses, I prefer to punch the blade from
the sheet, owing to the facility with which a projecting piece may be left upon it,.
and which piece may be utilized for mounting the handle. Probably the most
substantial construction however, is to provide a saddle-piece (Figs. 10, 11 & 12,.
Sheets 1 & 4.) which, as its name implies, is to be placed over or around the contact.
blade, and rivetted or otherwise secured to it. This saddle then form the projection.
upon which the handle can be conveniently placed. It will be seen by reference to-
the drawing that the sides of the blank J are doubled over so as to enclose and.
retain between them the strengthening wire L.
By the above description, I have shewn how it is possible to produce all the
essential parts required for a switch of the "knife-blade" pattern (Figs. 12 & 13,.
Sheets 4 & 1) by means of press and stamping tools.
Further modifications and improvements will naturally suggest themselves to.
those versed in the art of making electrical circuit-breaking devices.
As an illustration, for some requirements it is desirable to make a switch in.
which the operating handle is not solidly fastened to the contact blade. The
handle can be fastened to the blade through the medium of a flexible spring or
other like device. A switch of this description is shewn in Fig. 11 Sheet 1: in
this case the handle saddle is provided with an extra projection / to which is
secured at one end a spiral spring; the other end of the spring being secured to
the contact blade. In this construction the saddle K is not fastened to the blade ;
but is mounted upon the pivot-pin y afore-referred-to. If now the handle is

page_text: operated the movement is transmitted through the spiral spring, so that the blade
remains in the clip until the tensional force of the spring overcomes the friction of
the surfaces in contact, when the blade will be thrown out of the clip independently
of the will of the operator. This is the "snap" or "quick-break" principle; the
application of which to switches is well known by those versed in the art.
A switch of the description shewn in Fig. 12 provides simple means whereby it
can be readily combined with a fuse-attachment. Said attachment comprises the
block or base U made to conform to the end of the base of the switch; that part
of the pivot-clip which extends over the base of the switch, entering the slot v of
the block U. The block or base U is held in position by screws passed through
the holes z into the switch-board. The slot is divided by the upwardly projecting
piece u. In the slot at the other side of the block U-the stamping (afore-
described and shewn in Fig. 9, Sheet 1,) is secured. The fuse consists of a wire W
which connects the two binding-screws w and r.
This arrangement of switch and fuse is a very economical one as manufacturers
and dealers in switches will not have to keep a stock of every different size of
. switch, both with and without fuses, as they are compelled to do at present. One
set of stampings will make up either for fuse or fuseless switches, and a fuseless
switch can be transformed into a fuse switch by adding the base U.
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. The hereinbefore described method of manufacturing electrical switches, said
method consisting in stamping or otherwise cutting and forming the whole of the
parts of said switches out of sheet metal, substantially as and for the purposes
hereinbefore set forth.
2. An electrical switch constructed of one metal only, said metal being preferably
copper, substantially as and for the purpose herein before set forth.
3. In an electrical switch, the contact-clip stamped or otherwise formed from
sheet metal, the side pieces of said clip bowed and made substantially in the shape
hereinbefore described and shewn, a projection made integral with said clip to form
a rest for the switch-blade, and said clip reinforced by means of an auxiliary
stamping or by bending under a portion of the base of said clip, all substantially as
and for the purposes herein before set forth.
4. The hereinbefore described method of and means for combining a switch and
fuse said method and means consisting in detachably securing to the switch-base
an auxiliary base provided with a fuse and terminal, substantially as and for the
purpose hereinbefore set forth.
Dated this 2nd day of March 1894
W. H. MUNNS,
55, Chancery Lane, London, W.C., Applicant's Agent.