IMPROVED APPARATUS OR MECHANISM FOR INTERLOCKING RAILWAY SIGNALLING SWITCH AND FACING POINT APPARATUS
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Walter Parker Smith at the
Office of the Commissioners of Patents, with his Petition, on the
5th March 1875.
I, WALTER PARKER SMITH, of Lostwithiel, in the County of Cornwall,
Engineer, do hereby declare the nature of the said Invention for
"IMPROVED APPARATUS OR MECHANISM FOR INTERLOCKING RAILWAY SIGNALLING
SWITCH AND FACING POINT APPARATUS," to be as follows:-
The present Invention relates to improved machinism for the inter-
locking of signalling switches and facing point apparatus on railways.
So far as regards the application of these improvements to the
interlocking of the levers of the signalling switches and facing point
apparatus, this Invention comprises the combining and using with each
of the ordinary oscillating levers of an additional part capable of a
partial rotatory movement independently of the oscillating movement of
the lever, of which it also partakes, and further, the combining and using
with each of the series of ordinary locking bars of a series of locking bar
carriers, which are arranged in number and position corresponding to
the levers of the various signals, switches, or facing points, which their

page_text: locking bar is intended to control. To those conversant with mechanism
of this class this will be clearly apparent.
The rotatory part of the lever may be formed of an ordinary flattened
section of bar rounded at an upper and lower part and working in
bearings at such parts projecting from the lever so as to allow of its
rotatory motion, which may be imparted by the signal man turning a
handle or cross piece at its top.
The quadrant is provided as usually with the ordinary guide slots for
the separate levers, each of which slots at one end I make or form with
a circular enlargement to allow of the rotatory motion being given to
the flattened bar (the additional part of the lever), which, when the lever
is in its normal position, rests in the circular enlargement of its slot with
its flat side across the narrow exit, into the slot in which position it is
thus locked, and thus locks the lever and prevents it from being
moved until it can be and is turned in its rotatory motion, when it is
brought with its edge towards the narrow exit into its quadrant slot along
which and in which position it is then moved with, and partakes of the
ordinary reciprocating motion of the lever, which as ordinarily actuates
the signals, switches, or facing points. The capability of this rotatory
motion being given to the said additional part of the lever (so as to
unlock the latter) is however controlled and governed by the position
of the carrier upon the locking bar with respect to that part of the
additional part of the lever with which it engages; this will be at once
understood; for an example suppose that the carriers on any one
locking bar are arranged to work in connection with the levers of
the up main and down main signals only (and this will equally well.
serve as an illustration of any other combination however complicated)
so as to prevent the possibility of conflicting signals being given on the
road governed by these signals; in this instance the locking of (say) the
down main signal lever is effected in the following manner:―Before
the up main lever can be moved along its slot in the quadrant to
actuate its signal as ordinarily its additional part is first partially rotated,
which (as above stated) brings it edgeways towards its quadrant slot,
along which it can then be removed to actuate its signal, and which also
causes it to engage with and carry along its carrier and locking bar, so
as to effect the position of the other carrier on the locking bar with
respect to the down main lever in such a manner as to prevent the
additional part of this lever from being turned, and consequently so as

page_text: to prevent the lever being drawn along its slot to actuate its signal; it
will thus be seen that the possibility of confliction between the signals
governing this line or road is entirely prevented. The same result is
similarly obtained in any other combination.
Modifications of this principle of action may be applied to the locking
of switches or facing points in position, and to effect such an application
I apply underneath the point rails a transverse shaft, to which a rocking
motion may be imparted by any convenient mechanism from an ordinary
point locking lever.
The locking of the rails is effected thus:-Two locking pieces on the
rocking shaft respectively engage alternately on opposito sides of the
opposite point rails subsequently to their being shifted as ordinarily, and
keep them in position till their lever is again actuated.