IMPROVEMENTS IN THE MEANS OR APPARATUS FOR COMPENSATING FOR THE CONTRACTION AND EXPANSION OF RAILWAY SIGNAL OR POINT WIRES
Year: 1876

page_text: LETTERS PATENT to James John Frederick Stevens, of Darlington Works,
Southwark, in the County of Surrey, Railway Signal Manufacturer, for the
Invention of "IMPROVEMENTS IN THE MEANS OR APPARATUS FOR COMPENSATING
FOR THE CONTRACTION AND EXPANSION OF RAILWAY SIGNAL OR POINT
WIRES."
aled the 1st September 1876, and dated the 2nd March 1876.
PROVISIONAL SPECIFICATION left by the said James John Frederick Stevens
at the Office of the Commissioners of Patents on the 2nd March 1876.
JAMES JOHN FREDERICK STEVENS, of Darlington Works, Southwark, in the
County of Surrey, Railway Signal Manufacturer. "IMPROVEMENTS IN THE MEANS
OR APPARATUS FOR COMPENSATING FOR THE CONTRACTION AND EXPANSION OF
RAILWAY SIGNAL OR POINT WIRES."
The object of my Invention is to provide means for compensating for the
contraction and expansion of railway signal or point wires owing to changes of
temperature, and the Invention consists in attaching mechanisin to the signal or
point lever in the frame, so that any expansion of the wire is always at once taken
up and any contraction allowed for, while the wire is always ready to be acted upon
by the lever.
The manner in which I carry my Invention into effect is as follows:-To the
signal or point lever I secure a toothed wheel or part of a toothed wheel which is
free to turn on its axis. lead the wire over this wheel and fix the end thereto,
and I attach a weighted rod to the wheel. Upon the signal or point lever I fit a
block free to slide thereon, and with one or more teeth or projections to take into
the wheel above mentioned. This block has a pin at the side which works in a
cam guide. So long as the lever remains in its normal position the cam guide keeps
the teeth of the block clear of the wheel, so that the wheel being pulled in one
direction by the wire in case of contraction, or in the other direction by the weight
in case of expansion, the wire is always kept at the proper degree of tightness.
But as soon as the lever begins to be pulled over, the cam guide causes the block to
descend so that one or more of its teeth takes into the toothed wheel, and the
movement of the lever thus acts upon the wheel and moves the wire.
0

page_text: In some cases instead of the block and cam guide I extend the ordinary catch
rod which holds the lever in its forward and backward positions and I fit to the
lower end of the extension a pawl or tooth to take into the wheel when the catch
rod is lifted. Or I employ for this purpose an additional rod parallel with the
catch rod.
In either of these cases the notch at the back of the segment into which the
catch drops when the lever is in its backward position should be sufficiently shallow
to prevent the rod dropping far enough to lift the tooth out of the wheel.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said James John Frederick Stevens in the Great Seal Patent Office on the
2nd September 1876.
JAMES JOHN FREDERICK STEVENS, of Darlington Works, Southwark, in the
County of Surrey, Railway Signal Manufacturer. "IMPROVEMENTS IN THE MEANS
OR APPARATUS FOR COMPENSATING FOR THE CONTRACTION AND EXPANSION OF
RAILWAY SIGNAL OR POINT WIRES."
The object of my Invention is to provide means for compensating for the
contraction and expansion of railway signal or point wires owing to changes of
temperature, and the Invention consists in attaching mechanism to the signal or
point lever in the frame, so that any expansion of the wire is always at once
taken up and any contraction allowed for, while the wire is always ready to be
acted upon by the lever.
The manner in which I carry my Invention into effect is as follows:-To the
signal or point lever I secure a toothed wheel or part of a toothed wheel which
is free to turn on its axis. I lead the wire over this wheel and fix the end thereto,
and I attach a weighted rod to the wheel. Upon the signal or point lever I fit
a block free to slide thereon, and with one or more teeth or projections to take
into the wheel above mentioned. This block has a pin at the side which works in
a cam guide. So long as the lever remains in its normal position the cam guide
keeps the teeth of the block clear of the wheel, so that the wheel being pulled
in one direction by the wire in case of contraction, or in the other direction by
the weight in case of expansion, the wire is always kept at the proper degree of
tightness. But as soon as the lever begins to be pulled over the cam guide
causes the block to descend so that one or more of its teeth takes into the toothed
wheel, and the movement of the lever thus acts upon the wheel and moves the
wire.
Figure 1 of the accompanying Drawings represents apparatus constructed
according to my Invention as herein-before described. A is the signal or point
lever; B is part of a toothed wheel secured to the lever and free to turn on its
axis C; D is the wire, it is carried over a groove in the wheel and its end is fixed
thereto; E is a weighted rod attached to the wheel B; F is a block on the lever A
and free to slide thereon, it has teeth or projections as shewn to take into the teeth
of the wheel. It has also a pin G which works in a cam guide H. It will readily
be seen that so long as the lever A remains in its normal position, the cam guide H
keeps the teeth of the block F clear of the wheel B, so that the wheel being pulled
in one direction by the wire D in case of contraction, or in the other direction by
the weight E in case of expansion, the wire is always kept at the proper degree of
tightness, and as soon as the lever A begins to be pulled over, the cam guide H
causes the block F to descend so that its teeth take into the wheel B, and the
movement of the lever thus acts upon the wheel and moves the wire.
In some cases instead of the block and cam guide I extend the ordinary catch
rod which holds the lever in its forward and backward positions, and I fit to the
lower end of the extension a pawl or tooth to take into the wheel when the catch

page_text: rod is lifted. This modification is represented in Figure 2, in which I is the catch
rod with an extension K to which a pawl L is fitted. This pawl turns on the point.
M and takes into the teeth of the wheel (B, Figure 1), when the catch rod I is
lifted. Or I employ for this purpose an additional rod parallel with the catch rod,
as seen at N, Figure 3, which carries a block F the same as in the first arrange-
ment. This rod N is connected at its upper end to the catch rod I by means of
a piece O turning on the point P, so that when the catch rod is lifted the rod N
descends, and the teeth on the block F enter the wheel B.
In either of the modifications shewn in Figures 2 and 3, the notch at the back
of the segment (Q, Figure 1), into which the catch drops when the lever is in its
backward position, should be sufficiently shallow to prevent the rod I dropping far
enough to lift the tooth out of the wheel B.
And having now described the nature of my said Invention and in what manner
the same is to be performed, I declare that I claim as my "Improvements in the
Means or Apparatus for Compensating for the Contraction and Expansion of
Railway Signal or Point Wires," attaching mechanism to the signal or point lever
in the frame, so that any expansion of the wire is always at once taken up and
any contraction allowed for, while the wire is always ready to be acted upon by
the lever, substantially as herein-before described and represented in the annexed
Drawings.
In witness whereof, I, the said James John Frederick Stevens, have hereunto
set my hand and seal, this First day of September, One thousand eight
hundred and seventy-six.
JAMES JOHN FREDERICK STEVENS. (L.S.)