IMPROVE- MENTS IN CIRCUIT CLOSERS FOR ELECTRIC RAILWAY SIGNALLING APPARATUS
Year: 1875

page_text: LETTERS PATENT to William Clark, of 53, Chancery Lane, in the
County of Middlesex, Patont Agent, for the Invention of "IMPROVE-
MENTS IN CIRCUIT CLOSERS FOR ELECTRIC RAILWAY SIGNALLING APPARATUS."
- A communication from abroad by David Rousseau, of the City,
County, and State of New York, United States of America.
COMPLETE SPECIFICATION filed by the said William Clark at the
Office of the Commissioners of Patents, with lus Petition and
Declaration, on the 27th July 1875, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent Agent,
cond quenting

page_text: petitioned Her Majesty to grant unto me, my executors, administrators,
and assigns, Her Royal Letters Patent for the same, and have made
solemn Declaration that it has been communicated to me from abroad
by David Rousseau, of the City, County, and State of New York, United
States of America.
NOW KNOW YE, that I, the said William Clark, do hereby declare
that the following Complete Specification under my hand and scal fully
describes and ascertains the nature of the said Invention and in what
manner the same is to be performed in and by the following statement,
reference being had to the accompanying Sheet of Drawings, and to the
letters and figures marked thereon (that is to say) :—
The object of this- Invention is to utilize-the-proportionate clasticity
of railroad rails in connection with the weight of trains passing over the
same, for the purpose of establishing electric connection for operating
suitable signals to announce the approach or departure of such trains.
The Invention consists in placing beneath that part of the rail whose
depression is to be utilized, a plate supported on a cushion or spring,
and in the normal condition of the rail out of contact with a metal
spring or projection, that is, in connection with the conductor from an
electric battery. The least depression of the rail caused by the passing
over it of a train, locomotive, or carriage will lower the afore-mentioned
metallic plate into contact with the metallic projection of the conductor,
and thereby establish the circuit and operate the electric signal or other
apparatus in the desired manner. By this means a postive and in-
variably reliable electric circuit closer is produced, and the proper signals
for noting the approach of a train or locomotive at suitable distances from
such circuit closing device will be given without requiring any change
In the construction of the carriages or engines constituting the train or
any attachment thereto.
A modification consists in attaching to the upper plate of the circuit
closer a pendant sleeve, which carries at its lower end an annular plate,
and above said, annular plate another, both arranged to embrace a rod
that projects upwardly through them. Between these annular plates a
circuit closing sleeve is fitted upon the said rod in such a manner that
the least upward or downward motion of the rail and top plate will cause

page_text: end E of the conductor may project by its side toward the plate B,
although the former construction is in every way the most desirable,
since it serves to protect the metal E against the injurious influences of
moisture or atmospheric contact.
The portion E of the conductor may as shown be slotted to be adjus-
table on its connection with the conductor F, and to be brought at a
suitable distance from the plate B, which may be determined by the
varying degree of elasticity of the rails.
With special reference to Figures 3 and 4 which represent the
apparatus above described in a modified and perfected form, the letter A³
represents a portion of a railroad rail. Beneath the same and in contact
therewith is a metal plate B₁ resting on a rubber or other insulating
cushion or support C², which in turn rests upon a bed plate D².
The cushion C² is by preference made hollow to receive the end of a
telegraph wire or cable F, which enters into the hollow of the cushion
as shown. The rubber cushion C³ is flanged at the upper and lower
ends, the upper flange a entering within a pendant flange 6 of the top
plate B where it is confined in position by a screw ring E³, a washer
ring being interposed between such screw ring and the flange a³ of
the cushion. The lower flange e² of the cushion is confined in a similar
way by a screw ring G' in an upwardly projecting flange f² of the lower
plate or bed plate D³, a washer ring being interposed between the
flange e² and the ring G³. This mode of fastening the cushion is
preferable to that shown in the Figures 1 and 2, because it provides
more intimate connection of the parts. From the middle of the top
plate B is suspended into the hollow of the cushion 02, a metal tube H³
which carries within it at a certain distance above its lower end an
annular fixed plate ² that is in metallic connection with the body of
the tube The lower end of the tube receives a screw ring ³ of rubber
or other non-conducting material. It is a rod which rests with its lower
end on a non-conducting disk which is placed upon the bed plate D
The rod Iª extends through the ring, and also through the ring h², the
inner circumference of the latter named ring being provided with a non-
conducting lining, so as to prevent metallic contact between 2 and
1. is a sleeve which embraces the rod I² between the rings h², 2, and
which is by preference made of two semi-annular pieces of metal that

page_text: are pressed against the sides of the rod I³, by a surrounding rubber ring
as indicated in the Drawing. The upper surface of the sleeve is metallic
and has preferably projecting metal pins as indicated. The lower part
of the rod I is in metallic contact with the wire F.
:―
As thus far described the operation of the circuit closor is as follows:
The distance between the rings ³, 22, is so regulated that a very small
space will intervene for the play of the sleeve 12 between them, practically
not more than th of an inch.
When the parts are in the position indicated in Figure 3, that is,
when the cushion C² is fully expanded and the rail A² is not weighted
down, the metal pins on the surface of the sleeve will be a short
distance away from the metal ring h², and metallic contact between
the conductor F and rail A' will therefore be interrupted; but as
soon as a train passes over the rail, weighting the same down, the top
plate B² is depressed and with it the cushion, and by the motion of the
top plate the metal ring ² is carried down into contact with the metallic
parts of the sleeve . A current is thus established. Now if the down-
ward motion of the bed plate should under the pressure of a heavy train
be very large, it will cause the sleeve l² to move down with it, along, and on
the rod I, and while the sleeve is thus forced down by the ring h³, a pace of
about th of an inch will intervene between the lower part of the said
sleeve and the upper face of the ring 22, all as in Figure 4. After the train
has passed over the rail and the same is no longer weighted, the cushion C
will expand, and if the expanding motion be ever so small it will suffice
to carry the ring h² away from the sleeve 22, and thus to break the
circuit. If the expanding motion of the cushion C² be sufficient to raise
the rail to its original normal position, the sleeve will by contact with the
lower ring ² be raised in proportionate degree, yet its upper surface will
never be more than about th of an inch from the lower surface of the
metal ring, and consequently it will afterwards only require a short
downward motion of the rail under comparatively light pressure to re-
establish metal connection.
The conductor F is shown to be made in two pieces, one piece
pertaining to the instrument proper, and marked F³, and the other
piece leading to the instrument from underground and marked Fb.
The inner piece Fa, is coiled around the rod I², and is clamped to a

page_text: conductor Fa, carrying the plate p³, and with the cushion 7 and screw
s², substantially as and for the purpose specified.
In witness whereof, I, the said William Clark, have hereunto
set my hand and scal, this Twenty-seventh day of July, in
the year of our Lord One thousand eight hundred and seventy-
five.