Year: 1886

page_text: We, ALFRED THOMPSON and ROBERT ORD RITCHIE, both of 14 and 15 Saint
Swithins Lane, in the City of London, Engineers, 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 invention relates to improvements in the construction of apparatus for
making and breaking electrical circuits, more especially those on which heavy
currents, i.e. of large quantity, are worked, and has for its object the ensuring of a
much greater area of absolute contact between the surfaces of the fixed and moving
parts, usually employed in such apparatus, when they are brought together, than
is to be obtained in apparatus of the kind as hithertofore constructed.
It is well known that when the plane surfaces of any two metallic bodies, having
sufficient thickness to render them rigid, are brought into contact with each other
(the one being rigidly attached to a suitable base and the other moved by a lever
as obtains in nearly all the circuit breaking devices as at present used) that the
points of absolute contact are infinitely small as compared with the united areas of
the surfaces so brought into contact.
Now it is to remedy this defect and to provide means of always ensuring a large
area of absolute contact between the moving and fixed parts, when brought
together, that we have designed the apparatus hereinafter fully described and
shown in the annexed sheet of drawings.
In place of the usual arrangement of rigid castings by means of which the circuit
is completed or broken, as required, in apparatus of this kind as now made, we
employ a number of rolled, or malleable, thin, flexible metallic plates.
Any desired number of these plates, after being suitably arranged and spaced
apart by means of washers, or thickness pieces, are taken to form the terminal
points, while a corresponding number of plates similarly arranged and spaced
apart, are mounted upon a handle, or other suitable device, capable of rotation,
and form the moving, or contact making, part of the apparatus.

page_text: Each set of plates being so arranged and spaced that the outer ends of the
moveable plates shall exactly coincide with the spaces left between the inwardly
projecting ends of the fixed plates, which latter are, preferably, set radially to the
axis of the moveable plates.
By so spacing the plates apart as to ensure their being in intimate contact when
in position for completing the circuit and by making them sufficiently flexible to
allow of the several surfaces, when in contact, adjusting themselves one to the
other they yield collectively a much greater area of electrical contact than is to be
obtained in apparatus of the present or any known type.
Though flexible as regards their thickness the plates are so made as to prevent
any buckling or other distortion taking place, and although shown flat in the
drawings hereto annexed, it is to be distinctly understood that the plates may be
corrugated concentrically, or fluted in the direction of their length, or otherwise
suitably formed as might be found expedient.
Having thus set forth the object and nature of this our invention we will now
proceed to more particularly describe the same by reference to the annexed sheet of
Drawings.
Figure 1 is a plan of a five (5) way contact maker constructed in accordance
with our invention, and Figure 2 a sectional elevation of the same taken on the
line x, x.
Referring now to the Drawings it will be seen that a circular base A, constructed
of any suitable insulating material, has, centrally and perpendicularly mounted
upon it, and secured to it by any suitable means, a spindle or pivot B. A sleeve
like piece or casting, C, mounted upon the spindle B so as to be capable of rotation
thereon, and secured in place by the washer e and nut E, forms the foundation upon
which the moveable plates, constituting collectively the contact making and
breaking part of the device, are built up, and which, by its stiffness and large
bearing surface ensures their always moving in the same planes.
Any desired number of terminal points, 1, 2, 3, 4, 5, 6, Fig. 1 are arranged
radially upon the base and secured to it by the screws and nuts in the manner
shown. Each of these forms a foundation upon which a number of fixed plates,
together with their thickness pieces, corresponding to the number of moveable
plates are built up and secured by the bolts f, passing through them, and held by
the lock nuts g, g, as shown.
After the desired number of moveable plates a, a, interspersed with suitable
washers, b, b, have been built up upon the sleeve like casting C the handles D, D,
are placed in situ and the whole is then firmly bolted together by the bolts and
nuts h, and i in the manner shown.
To prevent any undue strains being transmitted through the bolts and nuts h
and when the handles are being used, the latter are keyed on to the sleeve C by
the set pins j, j, and thus the strains caused by turning the handles are transmitted
direct to the sleeve itself.
The fixed plates c together with their thickness pieces d are so arranged and
built up on the terminal points 1 to 6 that the outer ends of the moveable plates
shall just pass into the spaces left between the plates c, c.
Assuming the apparatus to be in use, and in the position shown in Fig. 1, then
the moveable plates will form a metallic bridge between the terminal points 1 and 6,
and the current entering at the latter point traverses the bridge so formed and
finally leaves the apparatus by the terminal F of the terminal point 1, it being
understood that the terminals may either project through the base, as shown, or be
taken off at the side, as required.
Similarly on placing the handles D, D, in the required position the moveable
plates are caused to form a metallic bridge between the terminal point 6 and any
one of the other terminal points, thus causing the current to pass in the required
direction.

page_text: 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 :
The construction of apparatus for making and breaking electrical circuits sub-
stantially in the manner as hereinbefore described and shown in the annexed
drawings.