Improvements in Contact-boxes for Electric Railways.
Year: 1897

page_text: Date of Application, 29th June, 1897-Accepted, 7th Aug.,
1897
COMPLETE SPECIFICATION.
Improvements in Contact-boxes for Electric Railways.
I, WILLIAM MILTON BROWN, of Johnstown, Cambria County, State of
Pennsylvania, United States of America, Electrical Engineer, do hereby declare
the nature of this invention and in what manner the same is to be performed, to
De particularly described and ascertained in and by the following statement:-
My invention relates to the contact boxes used in electric railways.
In a box of the class I employ there are the following elements: a base member
having a cavity, a switch member therein; which is here shown as a ball of iron or
steel floating in a body of mercury, and a cover composed of a centre of non-
magnetic material.
The object of my invention is to provide a contact box in which the switch
member is more readily removable and replaceable in case of accident to it and
to provide a box having certain other advantages hereinafter pointed out and
claimed.
Referring to the drawings: Fig. 1 represents a front view of a box embodying
my invention and Fig. 2 is a vertical section through the centre of Fig. 1.
A is the base of the box and is preferably made of wood, which may be creosoted
or otherwise treated with preservative, if desired. The iron plates B serve to spike
it to the tie upon which it usually rests.
Within this base is a cavity C adapted to receive the several parts as hereinafter
described; and upon the top of said base is secured the cover, composed of the
centre D of non-magnetic material such as brass or manganeso steel, and the two
sides of cast iron. This cover also has the cavity C, forming an addition to the
cavity C in the base. The switch member is here shown as a ball F floating in
mercury H. This ball and mercury are contained in a vessel' I, here shown as a
cup, which is formed in two parts, so that when the mercury and ball are in, it
may be sealed up. This cup is preferably formed of fibre, vulcabeston, porcelain
or other insulating material and is preferably so shaped that the diameter of the
mercury reservoir is large at the surface of the mercury and then quickly con-
tracts as shown. This prevents the surface level of the mercury falling to such
an extent when the ball is lifted, as it would were it not for this shape and at the
same time reduces the amount of mercury necessary to be used.
This
In the bottom of the cup I is placed, during the process of manufacturing the
cups or afterwards, the contact L, which passes entirely through the wall of the
cup, and is therefore in electrical connection with the mercury therein.
contact engages, by the thread / or otherwise, the pedestal O, to which the feeder
circuit is connected as at P. In the top of the cup is formed the other contact
piece R, adapted to make contact with the ball on the inside, and to receive the
connection S which is in turn electrically connected to the cover piece E. This
connection S should be of a length sufficient to allow of coupling up this con-
nection, before setting the cover down in its place.
The interior surface of the contact member R should conform closely to the
surface of the ball, so that the ball shall fit snugly therein, and not roll around on
its seat, which might have a tendency to cause an arc.

page_text: Should this box for any reason become dead or inoperative, it is only necessary
to remove the nuts from the four holding down bolts, and lifting the main cover
off, to remove the cup I, and substitute a new cun having the necessary ball and
mercury therein. These cups can be kept prepared and it is but the work of a few
minutes to replace an inoperative one.
2
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. In a contact box of the class described; a sealed' vessel removably secured
within said box containing a switching mechanism consisting of a solid conductor,
floating or immersed in a liquid conductor.
2. In a contact box of the class described, a sealed vessel containing a magneti-
cally operated switching mechanism, and removably secured within the contact-
box, an electrical conductor forming part of said vessel, said' conductor being
flexibly connected to the contact portions of said box.
3. In a contact box of the class described, a sealed vessel within said box, per-
manent electrical connections between a cavity within said vessel and the source
of electric supply and between the cavity and the contact portion of the box, a
fluid conductor within said vessel and a solid conductor floating, or immersed
therein, said vessel being removably secured within the contact-box..
4. In a contact box of the class described, a receptacle adapted to be removably
secured within the contact-box, said receptacle being sealed, a fluid conductor
within said receptacle and in electrical circuit with the source of supply, a solid
electrical conductor floating or immersed in the liquid conductor, said solid con-
ductor being adapted to be put in circuit with the contact portion of the contact-
box.
5. In a contact box of the class described, a receptacle having a cavity contain-
ing the switching mechanism, said cavity being sealed and having electric
conductors passing through its walls, said receptacle being fastened to a pedestal
electrically connected to the supply wire.