IMPROVEMENTS IN APPARATUS FOR WORKING AND INTER- LOCKING THE POINTS AND SIGNALS OF RAILWAYS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Robert Burn and Leopold
Joseph Green at the Office of the Commissioners of Patents, with.
their Petition, on the 17th September 1874.
We, ROBERT BURN, junior, and LEOPOLD JOSEPH GREEN, both of
Epsom, in the County of Surrey, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN APPARATUS FOR WORKING AND INTER-
LOCKING THE POINTS AND SIGNALS OF RAILWAYS," to be as follows:-
Our Invention relates to the construction, arrangement, and operation
of apparatus applicable to the levers employed for working railway
points and signals, the object of such apparatus being to effect the
releasing or the stopping of individual levers, and also the interlocking
of some of the levers with one another, so as to prevent the moving of
points and signals in contradiction to each other.
".
.
For the purpose of stopping a point or signal lever, or releasing-it,'
such lever is usually provided with a spring catch worked by the hand,
on grasping or letting go the lever. We dispense with such spring
catches worked by hand, and-effect the stopping and releasing of a point.
or signal by means of a treadle worked by the foot in the following.

page_text: manner :- -On the lever we fix an arc struck from the centre of motion
of the lever, with notches in its edge, and by the side of this arc we
mount a lever on a horizontal axis, such lever having at the one end a
treadle and at the other end a counterbalance weight or spring, and
having on it a stud which takes into one or other of the notches upon
the edge of the before-mentioned arc. When it is intended to move the
point or signal lever, the treadle is first depressed by the foot of the
operator, and the stud on the treadle lever is thus disengaged from the
notch in the arc, whereupon the point or signal lever can be moved.
When the treadle is relieved from the pressure of the foot the counter-
weight or spring causes the stud to engage in one or other of the notches
in the arc, whereby the point or signal lever is held fast in the position
to which it has been moved. Levers provided with stopping and releasing
treadles, such as we have described above, may be interlocked with one
another by means of any known suitable locking gear actuated by
the movement of the levers. In such cases we prefer to make the con-
nection from any one of the levers to the rod or wire by which its move-
ment is communicated to the point or signal with a certain amount of
play, as for example, by a pin working in a slotted hole, so that part of
the movement of the lever at each end of its stroke is inoperative on the
point or signal, whilst it is effective on the locking gear. Thus the
necessary interlocking is effected before the point or signal connected to
one of the levers is shifted.
For combining interlocking gear with the treadle apparatus described
above, so as to effect locking independently of the movement of the
hand lever, we connect the end of each of the treadle levers to an
upright bar guided to slide vertically in a framing. Some of the upright
bars of the system, as for example, those connected to the treadles of
signal levers, are provided with projections and hollows on their edges,.
others of the upright bars, as for example those connected to the treadles
of point levers, have rack teeth on their edges gearing with teeth on
rocking shafts mounted in bearings with their axes parallel to the row
of levers, and on these rocking shafts are projections and hollows
facing the hollows and projections on some of the bars first mentioned.
When a projection on one of the rocking shafts enters a hollow in
one of the bars, the movement of that bar is obstructed thereby, and
thus the treadle connected to that bar is prevented from moving, and
the lever to which that treadle belongs is locked. But when by the move-

page_text: ment of the treadle connected to the rocking shaft the latter is caused
to turn partly round on its axis so as to remove its projection from the
hollow in the upright bar, the latter is free to move and consequently the
treadle connected to it is released, and the lever belonging to that treadle
is unlocked. In a similar manner when projections on the bars engage
in hollows of the rocking shafts so as to prevent them from turning, the
treadles connected to those shafts are prevented from moving, and the
levers belonging to those treadles are locked. It is to be understood
that the projections and hollows on the several bars, and also those on
the rocking shafts, are to be arranged so as to effect the necessary inter-
locking of all the levers of the series to which the apparatus is applied.
It is obvious that instead of employing toothed gearing for working the
rocking shafts the latter may be turned through the required part of
their revolution by an arm engaging with a pin or notch on the upright
bar. It is also obvious that instead of arranging the bars in an upright
attitude they may be arranged horizontally, or in other directions as
they can be most conveniently accommodated, being worked by arms
from the treadle levers. We prefer however to arrange the bars upright
or nearly so, as in that case they serve to counterweight the treadles, and
special weights or springs for that purpose may be dispensed with.