IMPROVEMENTS IN THE MEANS OR APPARATUS FOR WORKING RAILWAY SIGNALS AND POINTS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by George Lund and Arthur Burrows
at the Office of the Commissioners of Patents on the 18th November 1878.
GEORGE LUND, of the Firm of Lund and Blockley, of 42, Pall Mall, in the City of
Westminster, Manufacturers, and ARTHUR BURROWS, of Nunhead, in the County of
Surrey. "IMPROVEMENTS IN THE MEANS OR APPARATUS FOR WORKING RAILWAY
SIGNALS AND POINTS."
Our Invention has reference to that description of apparatus for working railway
signals and points in which what is called a "repeater" is employed, the said
repeater being a sinall semaphore arm or indicator in the signal box, and connected
with the main semaphore arm or with the point, as the case may be, in such a way
that the movements of the latter are communicated to the repeater, so that it may
indicate to the signalman if the semaphore arm or point has obeyed the movement
of the signal or point wire or other connection. The apparatus or arrangements
hitherto adopted for operating the repeater have not been sufficiently reliable,
because the repeater has failed to indicate when through any cause the semaphore
or signal has stopped at a position intermediate between "danger" and "caution
if the point has not been fully opened or closed. Now our Invention overcomes
this defect by providing for a distinct action upon the repeater at an intermediate
position between "danger" and "caution" of the signal, or at an intermediate position
in the movement of the point, and this we effect by a single line wire.
"
or
A main feature of our Invention (which relates to operating the repeater
electrically) is, that at a certain part of the movement of the semaphore arm or of
the point a resistance coil is brought into action, so that there is first a stronger
and then a weaker power sent through the conducting wire, or vice versa, these
two powers being made to produce two distinct movements of the repeater.
The manner in which our Invention may be carried into effect when first a
stronger and then a weaker power is sent through the wire is as follows:-
Connected with the semaphore arm (we will describe the Invention as applied to
signals) are two springs, which as the semaphore arm falls or rises travel respectively
over two brass or other metal pieces. One brass piece is in connection with the
Din D31

page_text: battery, and the other goes to "earth." In the normal position of the semaphore
arm, that is to say when it is up, the spring which travels on the earth piece is
insulated therefrom, but as the semaphore arm falls the spring first completes the
circuit, and sends a current through the repeater, and acts upon it with full power;
the indicator of the repeater is thereby released from a lock which previously held
it and therefore falls, but is caught half way or at a certain point by a stop, then
as the semaphore arm continues to fall the spring which is in connection with the
battery passes over an insulated piece, and then comes in contact with a part or
continuation of the plate which is in connection with a resistance coil, the effect of
which is that the stop above mentioned being withdrawn owing to the current
being weakened, the current is able to move the repeater indicator the remaining
distance. Therefore should the signalman find that the repeater indicator stops
half way, he will know that the semaphore arm has also stopped half way, owing
either to the signal wire being slack or to some obstruction.
When the apparatus is arranged so as to send first a weaker and then a stronger
current to the repeater, the weaker current moves the repeater indicator until it is
caught by a stop or lock, and then the stronger current by overcoming the power
of a weight or spring which holds the stop or lock withdraws the said lock, and
allows the indicator to fall the full distance. In case, through slackness of the wire
or from other cause, the semaphore after falling its full distance should return to an
intermediate position, such movement would be at once shown by the repeater,
because a weaker current would then be sent so that the weight would fall; an arm
connected there with would in such fall shift the repeater momentarily past the
intermediate point, and the repeater would then again by the action of the weaker
current move against the lock or 'stop.
,
In order to provide ready means for tightening the signal wire when the
repeater shows it to be too slack, we lead a chain or cord from the end of the
signal wire over pulleys to a small winch attached to the signal lever, so that the
attendant can at once adjust the wire to the proper degree of tightness.