AN IMPROVED SAFETY SIGNAL FOR RAILWAYS
Year: 1857

page_text: PROVISIONAL SPECIFICATION left by William John Kendall at the Office
of the Commissioners of Patents, with his Petition, on the 21st December
1857.
I, WILLIAM JOHN KENDALL, of the City of Norwich, do hereby declare the
nature of the said Invention for "AN IMPROVED SAFETY SIGNAL FOR RAILWAYS,"
to be as follows:-
This improved safety signal is designed for the purpose of affording facility
to the signal man at a station or elsewhere on the line of railway to actuate a
signal or signals (attached to the locomotive engine) as the train passes the
signal post.
The signal post consists of a hollow cast-iron pillar, bolted to a suitable
foundation and surmounted by a board, upon which the word "signal" is
painted or otherwise marked in large characters.
In the interior of the signal post is a vertical rod or bar of iron, capable of
moving freely up and down, and to this bar is firmly attached an horizontal
arm of spring-tempered steel which passes through a vertical opening or slot
in the side of the signal post next to the railway, and projects a sufficient
distance in the direction of the rails to allow of its coming into contact with
one or other of two levers connected with the engine as it passes the signal
post. The vertical signal rod is jointed to the horizontal arm of a double
bell-crank lever which vibrates on a pivot or stud in a suitable bracket. To

page_text: each of the two vertical arms of the said lever is connected a chain attached
to a rod or wire. These rods or wires pass over pullies (supported by posts)
to the signal box where the signal man is stationed, where their ends are
united by a chain which passes once or twice round the barrel of a small
windlass, so that upon turning the windlass in either direction the spring
signal arm is raised or lowered in the signal post.
Upon the frame of the engine near the fire box is fixed an upright bolt or
spindle supporting two horizontal levers. These levers are of such a length,
and placed at such a height, that one or the other will come into contact (whilst
passing) with the spring signal arm above mentioned, according, as the said
arm is at its highest or lowest position in the signal post. The inner end of
each of these horizontal lovers is connected by a strong spiral spring with the
vertical arm of a bell-cranked lover working on a stud fixed to the fire box;
and to the horizontal arms of these two bell-crank levers two vertical rods
are attached, carrying at their upper extremities two plates, marked respec-
tively with the letters R (right) and S (stop), or with any other desired
signal. These signal plates are enclosed within a box having two slots in tho
upper part, through which they are respectively projected when one or other
of the signal levers comes into contact with the spring signal arm.
The signal
plates are furnished at the back with self-acting spring ratchets, which hold
them up when they are raised until released by the engineer pressing upon a
small knob outside the box.
The operation of this safety signal is as follows:-When the signal man
sees an approaching train or hears the whistle, he turns the windlass so as to
raise or depress the spring signal arm, which coming into contact with one or
other of the horizontal levers on the engine as the train passes the signal post,
will raise the corresponding signal plate, and thus call the attention of the
engine driver. It will be the duty of the engine driver to glance at his signal
box as he passes the signal post, but should he neglect to do so the sound
caused by the contact of the spring signal arm and lever and the overrunning
of the ratchet will not fail to attract his attention. When he has attended to
the signal he must press the knob, and the signal will again be ready for
-action.