IMPROVEMENTS IN APPARATUS FOR COMPENSATING THE VARIA- TIONS IN THE LENGTH OF SIGNAL AND OTHER WIRES
Year: 1877

page_text: LETTERS PATENT to Edward Burstow, of Horsham, in the County of Sussex,
and 91, Queen Street, Cheapside, in the City of London, Architect, for the
Invention of "IMPROVEMENTS IN APPARATUS FOR COMPENSATING THE VARIA-
TIONS IN THE LENGTH OF SIGNAL AND OTHER WIRES."
ealed the 11th December 1877, and dated the 13th June 1877.
PROVISIONAL SPECIFICATION left by the said Edward Burstow at the Office
of the Commissioners of Patents on the 13th June 1877.
EDWARD BURSTOW, of Horsham, in the County of Sussex, and 91, Queen Street,
Cheapside, in the City of London, Architect. "IMPROVEMENTS IN APPARATUS FOR
COMPENSATING THE VARIATIONS IN THE LENGTH OF SIGNAL AND OTHER WIRES."
The length of wires, more particularly those used for working railway and other
signals, especially where it is great, is subject to continual variations owing to
changes of temperature and other causes. Now my Invention is intended to pro-
vide a means by which, when the wire expands or becomes stretched, the slack will
be gathered up and drawn out of the direct line of the wire, and will so remain
without interfereing with the motion of the remaining or direct portion of the
wire until the wire contracts, when it will be again given out to form part of the
direct line.
The arrangement by which I propose to accomplish this, and which I find most
convenient for that purpose, consists of an arm placed approximately at right angles
to the direct line of the wire, and one end of which is capable of moving to and
fro with the wire on a fixed centre at the other end.
The moveable end of the arm adjacent to the wire carries a pulley or pulleys
over or between which some of the wire, left slack for that purpose, or a chain sub-
stituted for that portion of it, is drawn and retained by a weight suspended by it
over another pulley at or near the centre of motion of the moveable arm, so that
when the signal wire is moved either way that portion of the arm on which the
pulley or pulleys are fixed moves with it without drawing out that portion of the
wire which is passed between or over the pulley or pulleys.

page_text: In connection with the pulley at or near the centre of motion of the arm there
may be attached a brake with provision for loading the same, as may be required,
so as to check the too free motion of the wire or chain over the said pulley.
Other counterpoises may be attached at the signal end, or as may be required,
for the purpose of balancing the signal and gathering up the slack wire respectively.
On the wire being pulled by the action of the signalman's lever the arin and pulley,
or pulleys, move with the wire, transmitting the motion directly to the farther end
of it. The weight being heavier than the counterpoise at the signal will not yield
until the former has reached its limit of motion, and again when the signal is being
let down the wire will yield to the weight of, and give motion to the counterpoise,
and with it the signal, rather than to the weight on the slack, so that the wire
being always kept tight the signal always obeys the action of the signalman's
lever.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Burstow in the Great Seal Patent Office on the 13th
December 1877.
EDWARD BURSTOW, of Horsham, in the County of Sussex, and 91, Queen Street,
Cheapside, in the City of London, Architect. "IMPROVEMENTS IN APPARATUS FOR
COMPENSATING THE VARIATIONS IN THE LENGTH OF SIGNAL AND OTHER WIRES."
The length, especially when it is great, of wires used for working railway and
other signals is subject to considerable variation owing to changes of temperature
and other causes. Now my Invention provides a means by which when the wire
expands or otherwise becomes slack, the slack will be drawn out of the direct line
of the wire, and will so remain without interfering with the motion of the
remaining or direct portion of the wire until the wire contracts, when it will be
given out to again form part of the direct line, and thus the wire will be main-
tained in a tolerably equal state of tension.
The arrangement by which I accomplish this, and which I find most convenient
for the purpose, consists of an arm or pendulum approximately at right angles to
the direction of the wire; one end of the pendulum is attached to a fixed centre,
while the other end is free to move to and fro with the notion of the wire, and
carries a broad pulley or drum, round which the signal wire, or a chain substituted
for that part of it is carried, and from which, it passes over a pulley at the other
end of the pendulum, at or near the fixed centre, and finally has a weight sus-
pended from it by which it' is maintained in a proper state of tension.
The moveable end of the pendulum is connected with the signalman's lever by a
rod, chain, or wire, one end of which is hooked on to a brake so arranged that
when the signalman's lever is pulled the brake is acted on and first clamps the
drum, and then the free end of the pendulum is moved, drawing with it the
signal wire.
The arrangement is shown on the accompanying Sheet of Drawings, in which
Fig. 1 is a side elevation of the apparatus'; Fig. 2, a section; and Fig. 3, a front
elevation of the same.
A represents the moveable arm or pendulum which in Fig. 1 is shown drawn
back as when the signal is lowered; B, the fixed centre on which it moves, and on

page_text: which is also fixed the pulley C, which moves independently and freely. At or
near the free end of the pendulum is the drum D, round which the wire P, or a
chain substituted for that part of it, is carried as many times as may be necessary to
prevent its slipping, which will be for ordinary distances about 3 or + times, and
from thence the chain passes along the pendulum and over the pulley C, and has
suspended from the end of it the weight F. A brake consisting of a brake block
G, mounted on a rigid piece of metal H, is jointed to the pendulum by the pins J, J,
on which it moves as a centre, and which are secured by the screws K, K.
The pins J, J, may conveniently be distant from the centre of the drum about
one-sixth of the diameter of the drum; L is a fixed frame supporting the appa-
ratus, and M, M, stops to prevent the pendulum passing too far forward; N is a wire
or chain connecting the free end of the brake with the signalıman's lever. At the
signal post is a counterpoise by which the signal is so balanced as to rise into
the horizontal (danger) position when free, from which position it is lowered by the
pulling of the signal wire P, the variations in the length of which it is the object
of this Invention to compensate.
The manner in which the apparatus acts is as follows:-On the signalman
pulling his lever, the wire or chain N acting on the end of the brake causes it to
rise on the centre J, by which the block G is brought into forcible contact with the
surface of the drum D, which it clamps; and as the pull continues, the brake being
unable to rise further, then draws the end of the pendulum with it, pulling the
signal wire P, and lowering the signal. On the signalman's lever being released
the pendulum returns to its original position, the slackened wire allows the signal,
by the action of the counterpoise, to return to " danger," and finally the brake
releases its grip on the druin and again allows the action of the tension weight F
to come into play. In this condition, should any contraction or expansion of the
wire take place (as is continually happening under the changes of temperature) the
weight F will rise or sink (the pulley and drum turning freely with the motion of
the wire) and thus maintain the equable tension of the wire. It is only when the
signal is being lowered or held down that the brake comes into action and pre-
vents the free motion of the drum.
"
In crecting a signal the semaphore itself should first be so balanced that when
allowed free motion it will by a slight difference. of weight return to " danger;'
the wire P should then be attached, the weight F hung on, and if necessary added
to until it is sufficient to keep the wire in the desired state-of tension; this will
have overbalanced the counterpoise at the signal post, and lowered the signal, and
the former must now have further weight added to it until it is sufficient to cause
the signal to return to "danger."
3.
A catch taking into cogs on the surface of the drum D may be substituted for the
brake, but I prefer to use the arrangement above described.
What I claim as the Invention secured to me by the herein-before in part recited
Letters Patent is, the method of compensating the variations in the length of
signal and other wires by means of apparatus herein-before described, and for the
purpose set forth.
Signed & sealed by the
above-named Edward
Burstow, in the presence of
NEWNHAM BROWNE,
Patent Agent,
91, Queen Street,
Cheapside,
E.C.
EDWARD BURSTOW. (L.S.)