IMPROVEMENTS IN APPARATUS FOR INTERLOCKING RAILWAY POINT AND SIGNAL LEVERS."
Year: 1880

page_text: LETTERS PATENT to Walter Parker Smith, of Rosehill, Lostwithiel, in the
County of Cornwall, for an Invention of "IMPROVEMENTS IN APPARATUS FOR
INTERLOCKING RAILWAY POINT AND SIGNAL LEVERS."
PROVISIONAL SPECIFICATION left by the said Walter Parker Smith at the
Office of the Commissioners of Patents on the 23rd January 1880.
WALTER PARKER SMITH, of Rosehill, Lostwithiel, in the County of Cornwall.
"IMPROVEMENTS IN APPARATUS FOR INTERLOCKING RAILWAY POINT AND SIGNAL
LEVERS."
In
My Invention relates to apparatus for interlocking the levers that work the points
and signals of railways so as to render it impossible to shift a point unless the
signals be in such a condition that the point can be shifted without danger, or to
lower a signal unless the points be in such a position that the signal can be safely
lowered. For this purpose I mount on radial arms in front of each lever a locking
bar which has a series of notches in its front edge, and in front of these notched
bars I mount a number of horizontal rocking shafts extending along the row of
levers. On these rocking shafts in positions facing some of the locking bars are
fixed arms or stops, each of which has its end shaped partly in the form of a
circular arc struck from the centre of the rocking shaft on which it is fixed.
one attitude of the stop when the rocking shaft has been turned partly round in
one direction the end of the stop fits into a notch in the locking bar facing it, this
notch being hollowed circularly for its reception, and in this case the bar is locked
so that it cannot be moved. In another attitude of the stop when the shaft has
been turned partly round in the opposite direction, its rounded end being withdrawn
from the notch in the locking bar, the bar is unlocked and can be moved, but when
it is so moved, its notch being no longer in a position suitable to receive the
rounded end of the stop, that stop is locked and cannot be moved, and consequently
the rocking shaft on which it is fixed is likewise locked. Some of the stops on the
rocking shafts having projecting ends which enter notches in some of the locking
bars, so that when any one of these bars is moved some of the shafts are turned
partly round thereby; but if any one of these shafts is by some of its stops being
engaged in notches of bars that are stationary prevented from being so turned then
[Price 6d1

page_text: the bar which would move it is locked. Each of the locking bars is connected to
the lever behind it, so that whenever the lever is moved along the quadrant the
locking bar is also moved, and if the bar be locked so that it cannot be moved, then
the lever connected to it is also locked. The connection of the locking bar to the
lever for this purpose may be arranged in various well known ways. For example,
there may be mounted at the side of the lever a shaft in the form of a flat bar
having a helical twist near either or both of its ends, and this shaft having on it a
crank arm linked to the locking bar; whenever the lever is moved along the
helically twisted part of the shaft it causes it to turn partly round and so to move
the locking bar. Otherwise the lever may be fitted to slide vertically in a socket
and have on it studs entering notches in the stationary quadrant at its side at each
each end of its stroke. The lever being connected by a sway beam to the locking
bar, when the lever is raised so as to lift its studs out of the quadrant notch for the
purpose of being moved along the quadrant, the locking bar is also moved, and if
the locking bar be locked by any of the rocking shaft stops as above described, then
the lever cannot be raised, and consequently cannot be moved along the quadrant.
According to another arrangement the locking bar instead of being connected as
above described to the lever may be connected to the spring catch rod of the lever,
and as this catch rod has to be raised out of the quadrant notch before the lever
can be moved the locking bar must thus be moved before the lever can be moved.
Thus, as each lever has its notched locking bar so connected to it that the movement
of the bar necessarily accompanies that of the lever, and as each of the rocking
shafts receives motion from some of these locking bars, by fixing on these rocking
shafts stops facing notches in some of the locking bars the unlocking of the
various levers can be arranged to suit the particular conditions of the set of points
and signals which they control, as may be understood from the following example :-
I will suppose that there is a point lever which works a set of points so as to set
the rails right for either a main line or a branch line, and that there are two signal
levers, one for the main line signal and one for the branch line signal; also, that
the notched locking bar of the point lever works rocking shafts which have stops
facing the notched locking bars of the two signal levers; then in one position of the
point lever, that is to say, when it has set the points right for the main line, ono stop
is clear of the notch in the locking bar of the main line signal lever, but another
stop is engaged in the notch of the bar belonging to the branch line signal. In this
condition the main line signal can be lowered, but the branch line signal cannot be
lowered, and if the main line be lowered then the notch in its bar engaging
the stop on the rocking shaft prevents it from turning and so locks the point lever.
In a similar manner, by suitably arranging the stops on the various rocking shafts
in relation to the notches in the various locking bars, the interlocking of all or any
number of the levers of a set can be effected.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Walter Parker Smith in the Great Seal Patent Office on the 20th
July 1880.
WALTER PARKER SMITH, of Rosehill, Lostwithiel, in the County of Cornwall.
"IMPROVEMENTS IN APPARATUS FOR INTERLOCKING RAILWAY POINT AND SIGNAL
LEVERS."
My Invention relates to apparatus for interlocking the levers that work the
points and signals of railways, so as to render it impossible to shift a point unless
the signals be in such a condition that the point can be shifted without danger, or
to lower a signal unless the points be in such a position that the signal can be
safely lowered. For this purpose I mount on radial arms in front of each lever a
locking bar which has a series of notches in its front edge, and in front of these
notched bars I mount a number of horizontal rocking shafts extending along the
row of levers. On these rocking shafts in positions facing some of the locking
bars are fixed arms or stops, each of which has its end shaped partly in the form
of a circular arc struck from the centre of the rocking shaft on which it is fixed.
In one attitude of the stop when the rocking shaft has been turned partly round
in one direction the end of the stop fits into a notch in the locking bar facing it,
this notch being hollowed circularly for its reception, and in this case the bar is
locked so that it cannot be moved. In another attitude of the stop when the
shaft has been turned partly round in the opposite direction, its rounded end being
withdrawn from the notch in the locking bar, the bar is unlocked and can be
moved, but when it is so moved its notch being no longer in a position suitable to
receive the rounded end of the stop that stop is locked and cannot be moved, and
consequently the rocking shaft on which it is fixed is likewise locked. Some of
the stops on the rocking shafts have projecting ends which enter notches in some
of the locking bars, so that when any one of these bars is moved some of the shafts
are turned partly round thereby; but if any one of these shafts is by some of its
stops being engaged in notches of bars that are stationary prevented from being 80
turned, then the bar which would move it is locked. Each of the locking bars is
connected to the lever behind it, so that whenever the lever is moved along the
quadrant the locking bar is also moved, and if the bar be locked so that it
cannot be moved then the lever connected to it is also locked. The connection
of the locking bar to the lever for this purpose may be arranged in various
well known ways. For example, there may be mounted at the side of the lever
a shaft in the form of a flat bar having a belical twist near either or both of its
ends, and this shaft having on it a crank arm linked to the locking bar, whenever
the lever is moved along the helically twisted part of the shaft it causes it to turn
partly round and so to move the locking bar. Otherwise, the lever may be fitted
to slide vertically in a socket, and have on it studs entering notches in the
stationary quadrant at its side at each end of its stroke. The lever being connected
by a sway beam to the locking bar, when the lever is raised so as to lift its studs
out of the quadrant notch for the purpose of being moved along the quadrant the
locking bar is also moved, and if the locking bar be locked by any of the rocking
shaft stops, as above described, then the lever cannot be raised and consequently
cannot be moved along the quadrant. According to another arrangement the
locking bar instead of being connected, as above described, to the lever may be
connected to the catch rod of the lever, and as this catch rod has to be raised out of
the quadrant notch before the lever can be moved the locking bar must thus be
moved before the lever can be moved. Thus, as each lever has its notched
locking bar so connected to it that the movement of the bar necessarily accom-
panies that of the lever, and as each of the rocking shafts receives motion from
some of these locking bars, by fixing on these rocking shafts stops facing notches.

page_text: in some of the locking bars the locking and unlocking of the various levers can be
arranged to suit the particular conditions of the set of points and signals which
they control, as may be understood from the following example:-I will suppose
that there is a point lever which works a set of points so as to set the rails right
for either a main line or a branch line, and that there are two signal levers, one
for the main line signal and one for the branch line signal, also that the notched
locking bar of the point lever works rocking shafts which have stops facing the
notched locking bars of the two signal levers, then in one position of the point
lever, that is to say, when it has set the points right for the main line, one stop is
clear of the notch in the locking bar of the main line signal lever, but another
stop is engaged in the notch of the bar belonging to the branch line signal. In
this condition the main line signal can be lowered but the branch line signal
cannot be lowered, and if the main line be lowered then the notch in its bar
engaging the stop on the rocking shaft prevents it from turning and so locks the
point lever. In a similar manner, by suitably arranging the stops on the various
rocking shafts in relation to the notches in the various locking bars, the interlocking
of all or any number of the levers of a set can be effected.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a transverse section of a frame for a set of point and signal levers,
shewing one construction of interlocking gear according to my Invention. A is
one of the point or signal levers, which can be moved along the quadrant B in the
usual way.
At C, on the side of the lever A, are mounted two rollers, between
which is engaged a curved bar D. This bar is mounted on the framing by radius
links E so that it can move like the blade of a parallel ruler, every point in its
length travelling in a circular arc. Over the bar D are mounted in the framing a
number of rocking shafts F which extend longitudinally along the row of levers.
Over each of the bars D, which is made with a number of notches along its upper
edge, some of these rocking shafts have fixed on them curved arms H, H¹, some of
which, as H, when its rocking shaft is turned partly round into one position,
engage with the edges of notches in the bar D, and so prevent it from being raised,
and others, as H³, when its rocking shaft is turned partly round into another
position, escape the edges of the notches in D, leaving it free to rise. On the
bar D there are protuberances d against which the rollers C bear when the lever A
is at the extreme of its stroke. In beginning to move the lever A from the position
shewn in Fig. 1, so as to shift a point or lower a signal, the rollers C acting on
the protuberance d must lift the bar D. If owing to the engagement of one or
other of the rocking shaft arms, such as H, the bar D is prevented from rising,
then the lever A cannot be moved but remains locked until all the arms H have by
the movement of others of the set of levers been brought into a position, such as that
of H', leaving the bar D free to rise. If this be the case, the lever A can be moved,
and its rollers Cacting on the protuberances d raise the bar D at the beginning of the
lever's motion, and while the lever is moved over to the end of its stroke the rollers C
running along the curved portion of the bar D sustain the bar in the position to
which it had been moved. By the rising of the bar D one of the rocking shaft
arms, such as H', is turned partly round, and other arms on this rocking shaft are
thus caused to be engaged with or disengaged from the edges of notches on bars. D
belonging to other levers of the set. When it is required to effect locking and
unlocking by the movement of a lever at both extremes of its stroke, the apparatus
may be arranged as shewn in Fig. 2. In this case there are two bars D, the one
mounted in front of the lever, and the other behind it, each being made with a
hollow and protuberance at d. The lever A also has two arms K which, sliding
along the undersides of the bars D while the lever A travels, sustain them in the
position to which they are respectively raised when the movement of the lever
begins. The bars D instead of being moved at the first and last parts of the stroke
of the lever A may be arranged to be moved before the lever A begins to move,

page_text: or after it has completed its movement, as shewn in Fig. 3. In this arrangement
the rollers C instead of being mounted on the lever A itself are mounted on the
catch rod L, which is extended below the quadrant to receive them. Before the
lever A can be moved the catch rod L has to be raised so as to lift it out of
the notch of the quadrant B. By raising L the rollers C are raised and consequently
the bar D is also raised. If, owing to the engagement of one of the rocking shaft
arms H, the bar D cannot rise then the catch rod L cannot be raised, and the
lever A therefore remains locked at the extreme of its stroke. If the bar D being
free the lever A should have been moved over to the right, then on bringing back
the lever to the position shewn in Fig. 3, and again dropping the catch rod L so as
to catch in the quadrant notch, the bar D will also be lowered and may again be
locked by the partial turn of some of the rocking shafts having arms H, such
partial turn resulting from the movement of other levers of the set. Fig. 4 shews
the arrangement of divided bars D actuated by the catch rod L which raises or
lowers one of the bars at one extreme of the stroke of the lever A, and raises or
lowers the other bar at the other extreme of the stroke, the arms K sustaining
their respective bars while the lever moves.
Having thus described the nature of my Invention, and in what manner the
same is to be performed, I claim in respect of apparatus for interlocking railway
point and signal levers,―
First. The combination of the notched bars D mounted on radius links E, the
rocking shafts F, and their arms H, H', with a point or signal lever A, substantially
as and for the purpose herein described with reference to Figs. 1 and 2 of the
accompanying Drawings.
Second. The combination of the notched bars D mounted on radius links E,
tho rocking shafts F, and their arms H, H', with the catch rod L of a point or
signal lever A, substantially as and for the purpose herein described with reference
to Figs. 3 and 4 of the accompanying Drawings.
In witness whereof, I, the said Walter Parker Smith, have hereunto set my
hand and seal, this Nineteenth day of July, in the year of our Lord One
thousand eight hundred and eighty.
WALTER PARKER SMITH. (L.S.)