Improvements in Rheostats and other Circuit Controllers.
Year: 1895

page_text: Date of Application, 18th June, 1895-Accepted, 20th July, 1895
COMPLETE SPECIFICATION.
[Communicated from abroad by CHARLES WILLMS, Manufacturer, of 409 North
Paca Street, Baltimore City, in the State of Maryland, United States of
America.]
Improvements in Rheostats and other Circuit Controllers.
I PHILIP ARTHUR NEWTON of the Office for Patents, 6 Bream's Buildings.
Chancery Lane in the County of London, Patent Agent, 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:-
The object of the present invention is to provide an improved rheostat of the
general class in which a plate of non-conducting material is used, over which the
contact arm moves, and which is provided with a series of contact pins passing
through the plate, and closing circuit through resistance material applied to the
under side of the plate, certain features of the invention relating particularly to such
rheostats of a special construction in which the resistance material is divided into
sections by a series of collecting sectors, consisting preferably of wires extending
across the resistance material. The invention relates in part also to other features
which are applicable generally to rheostats of this general class, and in other similar
constructions employing a contact piece and series of contacts.
For a full understanding of the invention, a detailed description of the same will
now be given in connection with the accompanying drawings forming a part of this
Specification, in which a rheostat of the preferred construction, embodying all the
features of the invention, is shown, and the features forming the invention will then
be specifically pointed out in the claims.
In the drawings,
Fig. is a top plan view of the rheostat ;
Fig. 2 is a bottom plan view of the same;
Fig. 3 is a cross section on the line 3 of Fig. 1;
Fig. 4 is a section on the line 4 of Fig. 3.
Referring now to said drawings. A is the rheostat block of insulating material,
B the contact arm moving over the top of the block a, the contact pins extending
through the block, b the resistance material on the under side of the block through
which the pins extend, and ec collecting sectors consisting of a series of wires
extending transversely across the resistance material. These wires are connected
at their outer ends to the contact pins a, and at their inner ends to pins 1. It is
found in practice, however, that these wires, especially the longer ones at the
wider portion of the resistance material, are liable to become loose in the resistance
material, and fail to make good contact with it, especially on account of the
expansion and contraction due to heat and cold. In accordance with the present
invention, however, this difficulty is avoided by placing midway of the wires,
especially of the longer ones, another series of pins, 2, which act as tension pins,
and, as shown, are preferably used to tighten the wires by pressing the latter
out of the straight line between pins a and 1. The wires are thus tightened,
the length of the wires between pins reduced, and any detrimental loosening
of the wires from expansion and contraction avoided. It will be understood that
the pins may be applied in any suitable manner, to secure the desired result of
holding the wires under proper tension at all times, and that more than one
such pin may be introduced between the end pins, if desired, this depending

page_text: somewhat upon the size of the rheostat and length of the wires, but it has
been found that one pin in constructions of the size in common use is sufficient.
Referring now to the other features of the invention, which relate to the parts
by which contact is made with the pins a, the contact arm B is mounted upon a
hub C, which is provided with a screw-threaded shank d extending through an
opening in the plate A, and secured therein by nut 3, so that the hub may be
readily introduced into and removed from the plate. The screw d also provides
a simple and convenient means for securing the rheostat in position, as it may
thus be screwed down upon any table or plate desired. The contact arm B is
secured upon the hub by means of a washer 4 and set nut e, so that the contact
arm may readily be removed. The contact arm carries at the end a hollow cap
or head, within which is a sleeve g, in which is mounted a rod h, spring-
pressed downward by spring 5 pressing against a shoulder on the rod, and the
inner end of the sleeve through which the rod passes, which rod carries at its
Hower end a contact piece 6, which is secured therein by a pin 7, and, as shown
in Fig. 3, is brought to quite a sharp edge, and preferably, as shown in Fig. 1, is
of sufficient length to extend over three of the contact pins a.
This contact piece
is preferably pivoted by being mounted loosely on or by the pin 7, so that the edge
of the contact piece will adjust itself to any inequalities of the surface over which
it moves.
This edge contact piece secures a good contact, as it will ent its way down
through any deposit on the pins, so as to always reach the metal, this feature
being particularly valuable, on account of the expansion of the material forming
the block A, which otherwise might prevent contact between the contact piece
and the pins, and, by mounting the contact piece loosely as described, so as to
be free to oscillate as it passes over the pins, the edge is always in position to
secure the longest contact possible, and will shift its angle in accordance with
the incline formed by the tops of the pins over which it lies at any time. By
the spring pressure upon the contact piece by spring 5, the contact piece will
follow down as the contact pin or pins wear, and thus secure contact independently
of wear on either of the members, and this spring pressure is of especial value
in connection with the oscillating contact piece.
The sleeve g is held from passing into the head f, so as to leave space enough
for the play of the rod h by a shoulder 8 abutting against the underside of the
contact arm, and this sleeve is slotted at its lower end, and the rod guided
therein by a pin 9 carried by the rod, and entering the slots on opposite sides,
so as to keep the rod from turning, and thus hold the edge of the contact piece 6
in position longitudinally of the pins. It will be seen that this construction
permits all the parts to be removed readily from the contact arm, when the
latter is removed from the block.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad, I declare that what I claim is :-
1. The combination with a rheostat having a body of resistance material forming
a path for the current, and divided into sections by a series of collecting sectors
consisting of wires extending across the resistance material, and secured at their
ends, of tension pins for the wires intermediate of their ends, substantially as
described.
2. The combination with a rheostat having a body of resistance material forming
a path for the current, and divided into sections by a series of collecting sectors
consisting of wires extending across the resistance material, and secured at their
ends, of tension pins for the wires intermediate of their ends, and placed out of
line with the end pins, substantially as described.
3. The combination with the insulating block A, and contact arın B carrying a
contact piece, of a series of contact pins a extending through the block, resistance
material on the opposite side of the block from the contact arm forming a path

page_text: for the current of gradually decreasing width, pins
corresponding to contact
pins a, and, on the opposite side of the path of resistance material, wires c con-
necting pins a and 1, and embedded in the resistance material, and tension pins 2
between pins a and 1. substantially described.
4. The combination of a series of contacts and a contact piece, one of said
members being movable relatively to the other, for making contact between the
contact piece and the different contacts, said contact piece having an edge by
which the contact is made, substantially as described.
5. The combination of a series of contacts and a spring-pressed contact piece,
one of said members being movable relatively to the other, for making contact
between the contact piece and the different contacts, said contact piece having an
edge by which the contact is made, substantially as described.
6. The combination of a series of contacts and a contact piece, one of said
members being movable relatively to the other, for making contact between the
contact piece and the different contacts, said contact piece having an edge by
which the contact is made, extending in the line of the contacts, and of sufficient
length to cover two or more of the contacts, substantially as described.
7. The combination of a series of contacts, and a contact piece pivoted to
oscillate transversely to the contacts, one of said members being movable relatively
to the other, for making contact between the contact piece and the different
contacts, said contact piece having an edge by which, the contact is made, substan-
tially as described.
8. The combination of a series on contacts and a spring pressed contact piece,
one of said members being movable relatively to the other, for making contact
between the contact piece and the different contacts, said contact piece having an
edge by which the contact is made extending in the line of the contacts, and of
sufficient length to cover two or more of the contacts, substantially as described.
9. The combination of a series of contacts and a spring-pressed contact piece
pivoted to oscillate transversely to the contacts, one of said members being
movable relatively to the other, for making contact between the contact piece and
the different contacts, said contact piece having an edge by which contact is made,
substantially as described.
10. The combination of a series of contacts and a spring-pressed contact piece
pivoted to oscillate transversely to the contacts, one of said members being
movable relatively to the other, for making contact between the contact piece and
the different contacts, said contact piece having an edge by which contact is made
extending in the line of the contacts, and of sufficient length to cover two or more
of the contacts, substantially as described.
11. The combination with insulating block A, of contact pins a on said block, a
contact arm moving over said block, and a contact piece carried by said arm, and
having an edge making contact with said contact pins, substantially as described.
12. The combination with insulating block A, of contact pins a on said block, a
contact arm moving over said block, and a contact piece carried by said arm, and
having an edge extending in the direction of movement of the arm, substantially as
described.
13. The combination with insulating block A, of contact pins a on said block, a
contact arm moving over said block, and a contact piece carried by said arm, and
having an edge extending in the direction of movement of the arm, and of sufficient
length to cover two or more of the pins, substantially as described.
14. The combination insulating block A and contact pins a on said block, of a
contact arm moving over said block, and a contact piece pivoted in said arm, to
oscillate transversely to the insulating block, and having an edge making contact
with said contact pins, substantially as described.
15. The combination with insulating block A and contact pins a on said block,
of a contact arm moving over said block, and a spring-pressed contact piece
pivoted in said arm, to oscillate transversely to the insulating block, and having an
edge making contact with said contact pins, substantially as described.

page_text: 16. The combination with insulating block A and contact pins a in said block, of
a contact arm moving over said block, and a spring pressed contact piece pivoted
in said arm, to oscillate transversely to the insulating block, and having an edge
making contact with said contact pins, and of sufficient length to cover two or more
of the pins, substantially as described.
17. The combination with block A, having contact pins a, of contact arm B
carrying the head f, sleeve g in said head, rod h mounted in said sleeve, and
spring-pressed toward the block, and edged contact piece 6 carried by said rod,
substantially as described.
18. The combination with block A, having contact pins a, of contact arm B,
removably mounted in said block, and carrying the head f, sleeve g in said head,
rod mounted in said sleeve, and spring-pressed toward the block, and edged
contact piece 6, carried by said rod, substantially as described.
19. The combination with contact arm B, of sleeve g mounted therein, rod in
said sleeve, and spring-pressed toward the block, a pin and slot guiding connection
between the rod and sleeve, and a contact piece carried by the rod, substantially as
described.
20. A rheostat having contact block A, hub C mounted thereon, screw d
extending outside of the rheostat, for securing the latter in position, and contact
arm B mounted on the hub, substantially as described.
Dated this 7th day of June 1895.
NEWTON & SON,
Agents for the Applicant.