Improvements in Railway Signalling Apparatus.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Railway Signalling Apparatus.
.
I WILLIAM SAUNDERS of 34 Park Grove Battersea Park Road London,.
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 :-
This invention relates to apparatus for operating railway signals, and is more
especially applicable to wire compensating devices such as described with reference
to my former Specifications of Letters Patent Nos. 8586 of 1893 and 9537 of 1893.
In apparatus hitherto constructed for operating railway signals when the arm has
been lowered to its safety position it is liable upon the expansion of the wire, to
rise to its danger position, and thus indicate that the train must stop although the
line is clear for it to proceed, any my present invention has. for its object to prevent
such wrong indication.
For this purpose I mount upon the signal post a pully over which passes the.
chain connected to the signal wire, to the free end of this chain is connected a
weight for keeping the wire taut, and upon the axis of the pulley is mounted loosely
an arm connected to the ordinary signal-operating lever pivoted to the post some
distance above the said pulley. A locking arm is likewise pivoted to the post
above the pulley.and is formed with a notch into which enters the outer end of the
arm on the axis of the pulley so as to lock the said arm and consequently the signal
Farm or semaphore in their lowest or safety position..
The parts are unlocked by means of a projection formed partly, around the inner
face of the pulley, one end of which when the pulley is rotated, upon the signal-man
releasing the wire bears against the lower end of the locking arm so as to push the
latter out of gear with the pulley arm and permit the latter being pushed into its
highest position by the continued movement of the aforesaid projection, two stops
on the post limiting the motion of the pulley arm. The said projection is so formed
as to permit the pulley to rotate sufficiently to allow of the full expansion of the
wire without unlocking the arm. The pulley may be provided with a second or
smaller weight so that should the chain, connected to the larger weight break, the
second weight will rotate the pulley so as to unlock its arm, and permit it, and the
signal arm, to rise to their danger position.
In order more clearly to understand my said invention I will describe the same
with reference to the accompanying drawings, in which, Fig. 1 is an elevation of an
ordinary signal post with my improved apparatus applied thereto, and Fig. 2 is an
elevation at right-angles to Fig. 1. Figs. 3, 4, and 5 are details to an enlarged
scale.
P is an ordinary signal-post, and A the signal-arm or semaphore a, a¹, is the
pulley mounted on the post in any suitable position and formed double so as to
receive the two chains b, b', connected to weights c, c', the chain b also passing
underneath the guide-pulley d and being connected to the signal-operating wire,
whilst the chain ¹ is connected to the periphery of the pulley a¹.
e is an arm mounted loosely on the axis a² of the pulley, and to this arm is
pivoted the rod f for operating the signal A by means of the usual pivoted lever f¹³,
and rod f, g is a locking arm pivoted at g' to the post, and formed with a notch g²
and a lower extension g³. When the signal is in its lowered position the outer end
of the arm e enters the notch g' and is locked thereby. For the purpose of unlock-
ing the arm the pulley is provided with an extension / formed partly around its
inner face as shown more clearly in Figs. 3, 4, and 5.
When the signal-man releases the wire for raising the signal-arın the pulley is
rotated in the direction of the arrows until the projection comes into contact with

page_text: part g³ of the arm 9 and pushes the latter outwards until the notch g² is clear of the
arme thus unlocking the said arın and permitting of its being pushed upwards by
the extension. h-i, i, (Fig 1) are two stops fixed to the post for limiting the
travel of the arm e. When the signal is in its lowered and locked position,
the pully is free to partake of the movement of the signal wire in the event of the
latter expanding without operating the arm e, and semaphore A the extension / being
so formed that it will unlock the arm e only when the pulley has been sufficiently
rotated by the wire when operated or released from the signal-box as shown in
Fig. 4. For lowering the signal to the safety position the pulley is rotated, by the
pull on the wire, in the contrary direction to that shown by the arrows, until the
other end of the extension h comes in contact with the upper edge of the arm e
thus bringing the latter to bear against the stop i, when the notch g2 of the arm g
falls into gear with the end of the said arm e, and thus locks it, and consequently
the signal-arm A, in the "safety" position. Should the chain between the pulley
and the weight e break, the second weight cl will rotate the pulley in the direction
of the arrow thus unlocking the signal and raising it into its "danger" position.
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.
1. In railway signalling apparatus the combination of the pulley a, a', the
chains b, b, weight. c, c', arm e, and projection h, for operating the said arm,
stops i,, locking arm g, and semaphore operating mechanism f, f', and f",
substantially as described and shown in the accompanying drawings.
2. The improved railway signalling apparatus substantially as described and
shown and for the purpose specified.
Dated this 17th day of July 1895.
F. G. CASSELL,
Of Cassell & Co.,
22, Glasshouse Street, Regent Street, London,
Agent for the Applicant.