Improvements in Railway Signal Apparatus.
Year: 1899

page_text: Date of Application, 17th Aug.. 1899-Accepted, 7th Oct., 1899
COMPLETE SPECIFICATION.
Improvements in Railway Signal Apparatus.
We, CHARLES RICHARD GURR, of 30, Cranbrook Road, Chiswick, London, W.,
Builder and Contractor, and HERBERT TOMLINS, of 51, Cambridge Road, Hammer.
smith, London, W., 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 railway-signal operating mechanism and has for
object to compensate for variation of length of the wire connections through
which the signals are operated and to render impossible the partial or im-
perfect operation of the signals due to such variation. With this object the
wire connections are kept under constant tension and are at all times free to
expand or contract, being normally disconnected from the hand levers by which
the signals are operated; the coupling up of a hand lever with the corresponding
connecting wire being automatically effected at the moment when the signal
is to be lowered and the connections between the wire and the lever ceasing
immediately the signal is returned to "Danger.”
Reference is to be had to the accompanying drawings forming part of this
specification wherein Figure 1 is a general view of a signal and of the cabin
containing the lever by which it is operated. Figure 2 is a part sectional side
elevation of the coupling device. Figures 3, 4, and 5 shew a set of three in
different positions; Figure 3 being an end view and Figures 4, 5, sections (on
line 4-5 Figure 2) respectively shewing the device in and out of engagement.
Figure 6 is a part sectional side elevation of a modified construction of the
coupling device, the operation being however the same in the case of both
forms of construction. The same letters of reference denote like parts in all
the figures.
Referring to Figures 1 to 5 A is the hand lever in the signal cabin and S the
signal to be operated in the usual manner, that is to say the signal is normally
held at <
Danger" by a counterweight B except when pulled down by the
hand lever, this lever acting through the connecting wire C to which however
the lever is only temporarily coupled through the medium of the coupling device
to the free, rack-like, member D of which the wire C is connected. This
wire is constantly strained by a weight E which, acting in opposition to weight B,
necessitates the latter being made so much the heavier. ' is the guide frame
of the coupling device on which a carriage G is fitted to run, said carriage being
formed of two cheek plates provided with friction rollers embracing the guide
frame and also the rack bar D which are arranged parallel the one above the
other. The lower arm of the hand lever A is connected by a link H with
the carriage G through the medium of a cross pin I on which are mounted
rollers J that work in inclined cam slots K in the side cheeks of the carriage G.
The inclination of the cam slots corresponds to that of the ratchet-shaped teeth
of the rack bar D so that, immediately the link H is pulled, a downwardly
projecting spur L on the head of the link is caused to enter into positive
engagement with the rack bar D. This happens at the very commencement

page_text: of the movement of the hand lever A so that by the continued movement of
the latter the motion will be transmitted to rack D and wire C and the signal
will be pulled off. On the reverse movement of the hand lever the signal will
first be raised to "Danger" and the connection of the hand lever with the
connecting wire C will then be severed.
The rack is of sufficient length to ensure the making of the necessary con-
nection under all possible variations of length of the wire C. The rollers g of
the carriage permit free longitudinal sliding movement of the rack bar 1 to
accommodate the variations of length of the wire C whilst they maintain it
against any tendency to sag and ensure a secure connection of the spur with the
rack.
The construction shewn in Figure 6 only differs from the others in that the
relative positions of the fixed guide F and rack bar D are reversed and the cam
guided spur L (shewn in this case engaged with the rack) by which connection
is effected at the proper moment between link H and rack D, is situated between
them, the action being precisely similar in all respects.
Although it is obvious that the horizontal direction of working is preferable,
it is not obligatory.
In the working of this apparatus it will be apparent that should the wire C
undergo a considerable variation of length in the interval between two operations
of the signal which it controls, this difference of length will be taken up or
allowed for by the weight E and consequently the spur L on re-engaging with
the rack D will not engage the same tooth as on the previous occasion.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is: -
1. The herein described means of allowing and compensating for variations of
length of a signal-operating wire which consists in the combination with a
signal wire, normally disconnected from its operating hand lever and under a
constant tension, of an automatic connecting and disconnecting device inter-
posed between the hand lever and the wire and consisting of two normally
disconnected members adapted to be thrown into connection by the action
of cams at the initial movement of the operating hand lever substantially as
specified.
2. The herein described means of allowing and compensating for variations
of length of a signal-operating wire which consists in the combination with
a signal wire, normally disconnected from its operating hand lever and under a
constant tension, of an automatic connecting and disconnecting device interposed
between the hand lever and the wire and consisting of two normally dis-
connected members adapted to be thrown into connection by the action of cams
at the initial movement of the operating hand lever, the one member being a
rack connected to the wire and the other a spur connected to the hand lever
rod and combined with cam slots in a sliding carriage which have for effect
to throw the spur into or out of engagement with the rack and to maintain such
condition of engagement and disengagement substantially as specified.
1 11
1040
A. M. & WM. CLARK,
Agents.