Improvements in Apparatus for Compensating for the Expansion and Contraction of Railway Signal Wires.
Year: 1893

page_text: Date of Application, 18th Apr., 1893
Complete Specification Left, 18th Jan., 1894-Accepted, 24th Feb. 1894.
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Compensating for the Expansion
and Contraction of Railway Signal Wires.
I, ARTHUR GEORGE EVANS, of 116 Palace Chambers, Bridge Street,
Westminster, in the County of Middlesex, Civil Engineer, do hereby declare the
nature of this invention to be as follows:-
The object of my invention consists in automatic apparatus or means for main-
taining signal wires at one uniform degree of tension at all temperatures of the
atmosphere. It is well known that in cold weather the wire contracts and in hot
weather it expands, and that unless some apparatus is provided for compensating
for this expansion and contraction that railway signals or other apparatus worked
by wire fail to operate correctly.
I arrange a casting or bed plate in which works a blade one end of which is
connected to a signal lever, either directly or by means of wire, and the other end
connected to a weight. In the blade a slot is provided in which the spindle of a
toothed pulley moves. In addition to the teeth on the said pulley there are also
arranged recesses in the groove of the pulley to fit a chain. One end of a chain is
connected by wire to the signal arm and passes over the pulley and terminates in a
weight, being prevented from slipping by means of the recesses on the periphery of
the pulley. Arranged in the bed plate or casting is a stop so that the pulley
cannot travel towards the signal more than a specified distance. At one end of
the blade is fixed a tooth or pawl for holding the wheel or pulley when the blade
is operated by the signal lever. The blade is supported on rollers, top and
bottom, or a retaining pin may be provided at the top to retain the blade in its
position.
The operation of my invention is as follows:-Should the wire between the.
signal and the apparatus expand the weight attached to the wire is lowered
revolving the wheel by means of the recesses in its groove and so takes up slack
wire; should the wire contract the weight is raised and the pulley revolves in the
other direction. Thus the wire is maintained in a constant uniform tension,.
the principle being that the wire to the signal is normally disconnected from the
operating lever. When it is required to operate the signal the blade moves with
the forward movement of the signal lever until the tooth or pawl clutches. the
pulley when the whole apparatus, blade pulley and weight, travels in the direction
of the pull of the signal lever and deflects the signal. On the return motion of the
lever, the weight at the end of the blade pulls the blade back to its normal
position and disconnects the pawl from the teeth on the pulley, allowing the weight
attached to the wire from the signal to operate to compensate for expansion and
contraction.
JOHN P. O'DONNELL,
70 & 71, Palace Chambers, Bridge Street, Westminster, S.W.,
Agent for the said Applicant.

page_text: COMI DID WECIFICATION
Improvements in Apparatus for Compensating for the Expansion
and Contraction of Railway Signal Wires.
1, ARTHUR GEORGE EVANS, of 116 Palace Chambers, Bridge Street,
Westminster, in the County of Middlesex, Civil Engineer, 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 :-
The object of my invention consists in automatic apparatus or means for main-
taining signal wires at one uniform degree of tension at all temperatures of the
atmosphere. It is well known that in cold weather the wire contracts and in hot
weather it expands, and that unless some apparatus is provided for compensating
for this expansion and contraction that railway signals or other apparatus worked
by wire fail to operate correctly.
One end of a chain is
I arrange a casting or bed plate in which works a blade one end of which is
connected to a signal lever, either directly or by means of wire, and the other end
connected to a weight. In the blade a slot is provided in which the spindle of a
toothed pulley moves. In addition to the teeth on the said pulley there are also
arranged recesses in the groove of the pulley to fit a chain.
connected by wire to the signal arm and passes over the pulley and terminates in a
weight, being prevented from slipping by means of the recesses on the periphery
of the pulley. Arranged in the bed plate or casting is a stop so that the
pulley cannot travel towards the signal more than a specified distance. At one end
of the blade is fixed a tooth or pawl for holding the wheel or pulley when the
blade is operated by the signal lever. The blade is supported on rollers, top and
bottom, or a retaining pin may be provided at the top to retain the blade in its
position.
In order that my invention may be better understood and more readily carried
into effect I will proceed to describe the drawing hereunto annexed. The same
letters refer to the same parts in the several figures.
Figure 1 is a front elevation of the apparatus complete in the normal position.
Figure 2 is a front elevation of the apparatus with the signal lever operated and
the signal "off; it shows the toothed wheel moved forward and the pawl or tooth
upon the blade in engagement with a tooth on the wheel or pulley.
"2
Figure 3 is a plan on top of Figure 1.
Figure 4 is a general view showing the apparatus in position and the connections
to the distant signal.
a is the bed plate or casting, h is the blade connected to the lever at one end, e is
the pulley wheel, d are the teeth on the periphery of the wheel, e is that portion of
the wheel round which the chain operates, is the tooth or pawl fastened to the
blade b, g is a weight at the end of the chain attached to the wire leading to the
signal, h is a weight attached to a chain at the end of the blade leading to
the operating lever in the cabin, jj is the spindle of the wheel or pulley c, k is the
bearing on which the spindle revolves and moves, 1 is the end of the bearing
forming a stop, preventing, on the return stroke of the signal lever when the signal
is being replaced to "danger," the wheel or pulley c from moving beyond its normal
position. In Figure 4 m is the distant signal, n are the usual wire connections
operating the said distant signal m through the balance lever and weight o, o¹ on
the post, p is the operating lever in the signal cabin.
The action of my invention is as follows:-Assume the operating lever in the
signal cabin to be in the normal position and it is desired that the distant signal be
deflected, the said lever p is moved over and the wire and blade 6 are also moved,
the weight being thereby raised; in this action the pawl f engages with a tooth
on the periphery of the wheel c and moves the wheel c the weight 9 and the wire
g

page_text: attached to the signal m forward deflecting the said signal. Upon the return
stroke of the lever the weight assists the return of the blade or bar b to its
normal position, and the weighted balance lever upon the distant signal post returns
the bar to the normal position and assists in the return also of the pulley wheel c to
its normal position. The weight always ensures the disengagement of the pawl f
from the teeth on the periphery of the wheel c.
My apparatus is fixed in any suitable position between the operating lever in the
signal cabin and the distant signal.
Should the wire between the signal and the apparatus contract, then the pulley
wheel e is revolved, the weight y rising and allowing for the contraction; should
the wire expand then the weight g is lowered and the wheel revolved the requisite
amount of travel. The chain attached to the weight y maintains its grips on the
pulley wheel c by means of the recesses e.
Although I have described my invention in its application to a distant signal yet
it is obvious that it may be applied for the purposes of allowing for expansion and
contraction of signal wires to any signal.
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 :-
The combination of apparatus for compensating for the expansion and con-
traction of railway signal wires, substantially as described and illustrated in the
accompanying drawings.
Dated this 18th day of January 1894
companying drawings.
Dated this 18th day of January 1894
JOHN P. O'DONNELL,
Per W. B. L.,
70 & 71, Palace Chambers, Bridge Street, Westminster, S.W.,
Agent for the said Applicant.
JOHN P. O'DONNELL,
Per W. B. L.,
70 & 71, Palace Chambers, Bridge Street, Westminster, S.W.,
Agent for the said Applicant.