An Improved Electrical Bond or Connection for Railway and like Rails.
Year: 1897

page_text: Date of Application, 8th June, 1897-Accepted, 10th July, 1897
COMPLETE SPECIFICATION.
An Improved Electrical Bond or Connection for Railway and like Rails.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street, in
the City of London, Electrical Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by William B. Potter,
of Schenectady, County of Schenectady, State of New York, United States of America,
Electrical Engineer) and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
The so-called "plastic rail bonds" with which we are familiar are objectionable on
account of the amount of plastic compound employed, and because they permit the
escape of the mercury forming one of the elements of the compound, the metal
remaining forming a hard honeycomb structure, the conductivity of which is
impaired.
This invention has for one of its objects to provide a rail bond or connection of
high conductivity which is not open to the objections above pointed out, and one in
which a minimum amount of plastic compound is required. The invention further
has for its object to provide a reliable rail bond, cheap in its construction, and
requiring no finishing beyond that required to straighten the plates with which it is
provided.
In carrying out our invention, two flat plates are secured to the ends of a bundle, of
laminated copper; this can readily be done by placing the ends of the laminated
copper bundle in a mould, and pouring molten metal around them, which for all
practical purposes welds the copper to the plates, and secures good conductivity. The
plates are then put in a powerful press and straightened; at the same time the middle
portion is roughened by means of a die to form small pockets for the plastic compound.
The bottom surface of the ends of the rails to be united is then brightened, and the
plates applied thereto with a small amount of plastic compound between them.
Bolts or other clamping devices are then employed to secure the rails and plates
together.
By limiting the roughened surface of the plates to a point just inside of the outer
edges and applying them to the rails in a horizontal position, the mercury in the
compound bas no tendency to escape, and the smooth outer ends of the plates
engaging with the rail form in effect a shallow pocket.
In the accompanying drawing, Fig. 1 shows a side elevation of our improved rail
bond applied to a rail joint; Fig. 2 is a section of the same on the line 2-2 of Fig. 1,
and Fig. 3 is a plan view of the bond.
The rails A A¹ are connected by the fish plates B and B¹ and secured by the bolts C
in the usual manner. The plates D and D₁ of the rail bond are connected by the
bundle of laminated copper E. The plates D D¹ are bolted to the lower flange of the
rails A A¹ by the bolts F, the nuts of which are prevented from turning by means of
the bevelled spring washers L.
In constructing our improved rail bond the ends of the bundle of laminated
copper E are preferably inserted in a mould and the metal forming the plates D D¹
cast around them. If desired, holes K K, indicated by dotted lines, may be left in
the ends of the lamina E which will be filled with the molten metal, and will further
increase the conductivity of the bond and prevent the plates D D¹ from separating
from the copper strips E. The laminated bundle of copper E is preferably provided

page_text: with a bent or curved portion to enable the plates of the bond to be properly adjusted
with respect to the bolt holes in the lower flange of the rails.
In the construction of our improved rail bond, it is designed to do away with all
machine work beyond that required to straighten or true the plates. When the
plates D D¹ are put into the press for the purpose of straightening thein, they are
also roughened for a limited area, something in the manner of a coarse file. This
forms a series of points between which are small pockets G, which, when the plates
are assembled in place, are filled with the plastic compound I. To prevent the escape
of the mercury, the portion J of the plates D D' near the outer edge is left smooth.
In assembling our improved rail bond, the ends of the rails A A¹ are smoothed or
brightened, and the plates D D₁, with a limited amount of plastic compound filling
the pockets G, placed in position, and secured to the lower flange of the rails by the
bolts F.
Referring to Fig. 2, the relation of the parts will readily be seen. The plastic
compound I fills in the smaller pocket G, and a smaller portion will also cover the
surfaces J, thereby increasing the conductivity of the joint at this point. In the
drawing the amount of compound extending over these surfaces is somewhat
exaggerated for the purpose of illustration; it is intended that there shall be only a
small amount, just sufficient to make good contact between them. The surface J by
closely engaging with the under surface of the rail, prevents any tendency of the
mercury in the compound to escape, even though the rail be mounted slightly at
an angle.
We prefer to make the plastic compound of about the consistency of cement, and
apply an amount which is sufficient to fill the pockets G and cover the surfaces J with
a very thin coat.
The amount of the compound employed may be varied by making
the pockets G of greater or less extent; we aim, however, to use as small an amount
as possible in order to decrease the cost of the bond.
Having now particularly described and ascertained the nature of our said invention
(as communicated to us from abroad) and in what manner the same is to be performed,
we declare that what we claim is:-
1. In an electrical bond or connection for railway and like rails, the combination of
roughened plates, a conductor connecting the plates, a plastic compound of good
conductivity filling the roughened portion of the plates, and means for securing the
plates to the rails, substantially as described.
2. In an electrical bond or connection for railway and like rails, the coinbination of
two end plates, a laminated connection between the plates, each plate having a
limited roughened area, a plastic compound of good conductivity filling the roughened
area, and means for securing the plates to the rails substantially as described.
3. In an electrical bond or connection for railway and like rails, the combination of
two flat plates, a bundle of laminated copper having its end welded to the plates,
a number of small pockets covering a restricted area in each plate, a smooth surface
enclosing the small pockets and extending around the outer edge of the flat portion of
the plate which engages with the rail, a plastic compound of good conductivity filling
the pockets and means for securing the plates to the rails substantially as described.
4. An electrical bond or connection for railway and like rails comprising two plates
having flat surfaces each provided with a number of small pockets and a good
conductor connecting the plates substantially as described.