An Improved Rheostatic Apparatus particularly applicable to the starting of Electro-motors.
Year: 1897

page_text: Date of Application, 19th Mar., 1897
Complete Specification Left, 19th Jan., 1898-Accepted, 19th Feb., 1898
PROVISIONAL SPECIFICATION.
An Improved Rheostatic Apparatus particularly applicable to the
starting of Electro-motors.
I, GEORGE EDWIN DIXON, of 31, Snow Hill, in the City of London, Doctor of
Medicine, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved rheostatic apparatus more particularly
applicable to the starting of electro-motors, and the chief object of the invention
is to provide a simple and reliable apparatus so constructed that a comparatively large
increase of temperature due to the passage of the current can be permitted without
causing trouble or inconvenience to the operator and without damaging the apparatus,
whereby great capacity to absorb current is obtained with a device of comparatively
small dimensions.
An important feature of the invention consists in embedding the resistance coils,
wires or strips in a mass of vitreous enamel of the kind usually employed for
enamelling metal articles.
A further important feature consists in forming the base or body of the apparatus,
of iron or other suitable metal having heat radiating ribs or fins on one side thereof
and having the aforesaid mass of vitreous enamel applied as a coating to the other
side thereof.
According to one construction, the rheostatic apparatus comprises an iron base
provided with tubular legs or supports, and having a pivot pin or centre for movable
contact arm, the end of which works over a series of contact heads or studs, which are
connected through the iron base with resistance coils, wires or strips embedded in a
mass or layer of enamel on the underside of the base. The contact arın and the
contact heads are insulated from the iron base by suitable heat resisting material and
the heads are separated from each other by spaces of a width less than the end of the
arm, so that before the arm breaks contact with one it establishes contact with the
next. The arm is acted upon by a flat spring tending to press it upon the contact
heads, and is also acted upon by a spring tending to turn it on its pivot towards that
end of the series of contact heads corresponding to the highest resistance, in which
position the arın is brought to rest against an elastic stop or buffer. At the other end
of the series of contact heads is arranged a spring clip or tongue adapted to bear upon
the contact arm and hold it by friction.
A pair of suitably insulated terminals are secured to the base plate and are
connected say one to that end of the contact heads giving the least resistance, and the
other to the pivot of the contact arm.
The iron base plate is provided on its upper side with heat radiating ribs or fins of
the kind referred to, and the contact arm is arranged at such a height above the base
plate, that the said ribs do not interfere with the movements thereof.
Dated this 19th day of March 1897.

page_text: An Improved Rheostatic Apparatus particularly applicable to the
starting of Electro-motors.
I, GEORGE EDWIN DIXON, of 31, Snow Hill, in the City of London, Doctor of
Medicine, 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 an improved rheostatic apparatus more particularly
applicable to the starting and controlling of electro-motors, and the chief object of
the invention is to provide a simple and reliable apparatus so constructed that a
comparatively large increase of temperature, due to the passage of the current, can
be permitted without trouble or inconvenience to the operator, and without
damaging the apparatus, whereby great capacity to absorb current is obtained with
a rheostat of comparatively small dimensions.
An important feature of the invention consists in embedding the resistance coils,
wires or strips in a mass of vitreous enamel of the kind usually employed for
enamelling metal articles.
A further important feature consists in forming the base or body of the apparatus
of iron or other suitable metal having heat radiating ribs or fins on one side thereof
and having the aforesaid mass of vitreous enamel applied as a coating to the other
side thereof.
In order that the invention may be clearly understood and readily carried into effect
I will proceed to describe one form of the improved apparatus by aid of the
accompanying drawings.
In these drawings,
Figure 1 is a plan of the said apparatus.
Figures 2 and 3 are sections on the lines x x and y y Figure 1 respectively.
Figure 4 is an underside view of the apparatus.
a is the base of the apparatus. This base is formed of iron and is provided with
heat-radiating ribs a¹ and with tubular legs or supports b. c is a pivot pin or centre
for a movable contact arm d, the end of which works over a series of contact heads
or studs e. These contact heads are connected through the iron base with resistance
wires of iron or German silver embedded in a mass or layer of enamel f' on the
underside of the base. The contact arm and the contact heads are insulated from
the iron base by insulating thimbles g of suitable heat resisting material such as
vulcanized fibre, and the heads are separated from each other by spaces of a width
less than the end of the arm, so that before the arın breaks contact with one it
establishes contact with the next. The arm is acted upon by a flat spring h tending
to press it upon the contact heads, and is also acted upon by a spiral spring i tending
to turn it on its pivot towards that end of the series of contact heads corresponding to
the bighest resistance, in which position the arm is brought to rest against an
elastic stop or buffer k. At the other end of the series of contact heads is arranged
a spring clip or tongue adapted to bear upon the contact arm and hold it by
friction.
The contact arm is arranged at such a height above the base plate, that the ribs a¹
do not interfere with the movements thereof.
A pair of suitably insulated terminals m are secured to the base plate and are
connected one to that end of the contact heads giving the least resistance by a
strip m¹ and the other to the pivot c of the contact arm by a strip n.

page_text: 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 :-
1. A rheostat having its resistance coils, wires or strips embedded in enamel,
5 substantially as and for the purposes described.
2. A rheostat of the kind referred to in the preceding claim having a metallic base
provided with heat radiating ribs, substantially as described.
3. My improved rheostat constructed substantially as hereinbefore described with
reference to the accompanying drawings.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.