Switch Apparatus for the Graduated Inclusion and Exclusion of Resistances in Electrical Circuits.
Year: 1897

page_text: Date of Application, 15th May, 1897.
Complete Specification Left, 11th Feb., 1898-Accepted, 19th Mar., 1898
PROVISIONAL SPECIFICATION.
Switch Apparatus for the Graduated Inclusion and Exclusion of
Resistances in Electrical Circuits.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, Westminster,.
S.W., in the County of London, Electrical Engineers, do hereby declare the
nature of this invention (as communicated to us from abroad by Messrs. Siemens
& Halske, of Markgrafenstrasse 94, Berlin, S.W., Germany, Electrical Engineers),
to be as follows:-
This invention relates to an apparatus for the graduated inclusion or exclusion
of resistances into or from electrical circuits.
For this purpose pressure contacts are employed one part of which is of carbon
while the other part is of copper or other suitable metal, as it has been shewn
that such a combination contacts give comparatively short sparks on breaking
contact and is very durable.
A series of fixed carbon contacts, arranged in a circular arc, is suitably connected
with a corresponding series of resistances which are successively put in or out of
circuit by means of a metal roller or disc that is made to roll against the said
carbon contacts.
According to another modification the fixed contact plates are made of metal
and the rolling contact of carbon.
The construction of such switch apparatus is preferably as follows:-
Upon a base of insulating material are secured the carbon contacts, contained
in metal sockets or clamps by which they are connected to the step resistances;
on the base is fixed a bridge-shaped bracket carrying one end of a switch spindle
the other end of which is carried in a bearing on the base; the middle part of this
spindle is made of looped form and on an axis carried in this loop is mounted
the metal contact roller, the spindle being situated in the centre of the circular arc
formed by the carbon contacts, the rotation of the spindle causes the contact roller
to roll consecutively over the inward directed faces of the carbon contacts the
roller being pressed against these by a spring acting against its axis which is
carried in slotted holes in the loop of the spindle so as to allow of such pressing
action.
The contact roller is connected with the one lead of the circuit by means of a
spiral copper band one end of which is connected to the axis of the roller while
the other end is connected to an insulated screw post on the bridge shaped bracket.
According to another modification, instead of mounting the contact roller
with spring action on the loop of the spindle the roller axis may be fixed, and the
carbon contacts be mounted with spring action.
In this arrangement instead of having only a single set of carbon contacts and
roller, there may be two sets of carbon contacts mounted vertically over each other
on the two ends of vertical supporting bars having an eye at the middle with which
the bar can slide on a horizontal rod carried by a bracket on the base.
The supporting bar with the two contacts is pressed inwards by a helical spring

page_text: on the horizontal rod, and the eye of the bar is formed rounded so that the bar can
tilt somewhat out of the perpendicular in one direction or the other.
Two contact rollers are fitted one above the other on the central spindle so as
to be respectively in contact with one of the said two contact plates, a perfect
contact with both being insured by the above described spring adjustment of the 5
plates.
Switch Apparatus for the Graduated Inclusion and Exclusion of
Resistances in Electrical Circuits.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, Westminster,
S.W., in the County of London, Electrical Engineers, do hereby declare the
nature of this invention (as communicated to us from abroad by Messrs. Siemens.
& Halske, of Markgrafen Strasse 94, Berlin, S.W., Germany, Electrical Engineers,)
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 an apparatus for the graduated inclusion or exclusion
of resistances into or from electrical circuits.
For this purpose pressure contacts are employed one part of which is of carbon
while the other part is of copper or other suitable metal, as it has been shewn
that such a combination of contacts give comparatively short sparks on breaking
contact and is very durable.
A series of fixed carbon contacts, arranged in a circular arc, is suitably connected
with a corresponding series of resistances which are successively put in or out of
circuit, by means of a metal roller or disc that is made to roll against the said
carbon contacts.
According to another modification the fixed contact plates are made of metal
and the rolling contact of carbon.
We will describe the construction of the said apparatus with reference to the
accompanying drawings in which Figs. 1 and 2 shew respectively a diagram plan
and a vertical section of one construction, while Fig. 3 shews a diagram elevation
and Fig. 4 a vertical section of a modified arrangement, and Figs. 5, 6 and 7 shew
enlarged details thereof.
Referring to Figs. 1 and 2, on a base P of insulating material are fixed by
screws the carbon contacts K K contained in metal sockets or clamps by which
they are connected to the graduated resistances W, W. . . . On the plate P is fixed
a bridge shaped bracket B carrying one end of the switch spindle Z fixed to a loop
shaped frame R on the other side of which is a pivot Z¹ mounted in a bearing in
the base P, as shewn at Fig. 2. The frame R carries an axis N on which is
mounted loose the contact roller S. The ends of the axis N pass through and can
slide in slots E E, in the frame R, as shewn in dotted lines at Fig. 1, and the
axis is pressed outwards by a spring F acting on a looped piece r, pressing on the
axis. On rotating the spindle 7 and frame R by means of the handle, the contact
roller S will also be carried round and will at the same time be pressed by spring F
against the carbon contacts KK. . . . The contact roller is in conducting connection
with the binding post A. though the axis N and spiral copper band C, Fig. 2, con-
nected respectively to N and A, which latter is connected to the circuit terminal L'
Fig. 1, while the last left hand carbon contact K is connected to the terminal L'. A

page_text: current entering at L³ will consequently pass through a greater or less number
of the resistances to L¹, according to the position of the roller S.
It will be evident that the contacts K might be made of metal, and the roller S
of carbon, formed in any suitable manner.
Figs. 3 to 7 shew a modified construction of the switch apparatus in which the
carbon contacts K are mounted with spring action, in the khown manner while
the roller has no spring action.
Figs. 4 to 7 shew the arrangement with two sets of contacts KK and two
rollers S1, S2, for powerful currents. The carbon contacts K are here carried
in sockets which are moveably mounted on bolts D carried by brackets B, and are
acted upon by helical springs F.
The brackets B are connected on the one hand by the bent conductor C to the
contacts K, and on the other hand at W₁ to the resistance circuits.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is:-
1. Graduated resistance switch apparatus consisting of a series of fixed contact
plates such as K connected with the one terminal of a circuit through resistances
which are put successively in or out of circuit, and a contact roller such as S
mounted with spring action on a pivotted arm or bracket such as R which is
connected with the other terminal of the circuit, and by the rotation of which
the roller is brought successively in pressing contact with the fixed contact plates,
so as to include or exclude the resistances thereof, either the fixed contact plates
or the roller being made of carbon, while the other part is made of metal, sub-
stantially as described with reference to Figs. 1 and 2 of the drawings.
2. In graduated resistance switch_apparatus such as is referred to in the first
claim, arranging the fixed contacts K with spring action while the contact roller
or rollers S are mounted rigidly on the arm or bracket R, substantially as
described with reference to Figs. 3 to 7 of the drawings.
3. Graduated resistance switch apparatus with roller contact switch, combined
and operating as herein described with reference to the drawings.
Dated his
thie 11th day of February 1908.
ABEL & IMRAY,
Agents for the Applicants.
ABEL & IMRAY,
Agents for the Applicants.