IMPROVEMENTS IN INTERLOCKING APPARATUS FOR THE POINTS, AND SIGNALS, AND TELEGRAPHIC BLOCK INSTRU- MENTS OF RAILWAYS
Year: 1878

page_text: LETTERS PATENT to Charles Hodgson, of Canterbury Road, Kilburn, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN INTERLOCKING
APPARATUS FOR THE POINTS, AND SIGNALS, AND TELEGRAPHIC BLOCK INSTRU-
MENTS OF RAILWAYS.”
Sealed the 13th June 1878, and dated the 4th April 1878.
PROVISIONAL SPECIFICATION left by the said Charles Hodgson at the
Office of the Commissioners of Patents on the 4th April 1878.
CHARLES HODGSON, of Canterbury Road, Kilburn, in the County of Middlesex.
"IMPROVEMENTS IN INTERLOCKING APPARATUS FOR THE POINTS, AND SIGNALS, AND
TELEGRAPHIC BLOCK INSTRUMENTS OF RAILWAYS."
In the Specification of Letters Patent granted to me on the 31st January 1877,
No. 400, I described means of interlocking the points and signals of railways with
the telegraphic instruments used for communicating from station to station.
My present Invention relates to improvements in such apparatus, whereby I am
enabled to apply the interlocking gear in connection with telegraphic instruments
working with one conducting wire, without interfering with the ordinary use of
these instruments or with the use of the conducting wire for purposes of communi-
cation generally.
The instruments referred to usually have two operating keys, generally in the
form of spring plungers which are pushed in to send a signal, and having sent it
rebound to their former position, the one of the two plungers signalling "line clear,"
and the other "line blocked," and either capable of sounding a bell or other
audible signal. For working these plungers in accord with the interlocking gear,
described in the Specification above referred to, I fix on the spindle to which is
attached the handle for interlocking a two-armed lever, and I connect each of the
aforesaid plungers by a bell crank to a vertical rod linked to a pawl on each side
of the said spindle.

page_text: When the handle is turned in the one direction one of the lever arins by acting
on one of the pawls depresses one of the vertical rods, and so causes the one plunger
to be thrust inwards so as to send a signal, but when the handle has completed its
movement the arm of its lever escapes from the pawl and allows the plunger to be
moved outwards by its spring, the wire being thus left available for other purposes.
When the handle is turned in the opposite direction the lever arm that formerly
acted escapes its pawl, but the other arm catching the other pawl acts on the other
plunger in like mannor.
Instead of making the interlocking handle work the plungers, as above described,
it may be made to interlock with them, but without moving them, in the following
manner: On the spindle of the interlocking handle I fix a cam, against which bears
a lever arm. From this arm a bar extends across the two spring plungers, the bar
being notched and the plungers also being notched, so that in one position of the
handle both plungers facing notches in the bar are free to move, but the bar itself
cannot move until by pushing in one of the plungers a notch in it is brought to face
the bar. In the other position of the handle one of the plungers still remains free,
but the other plunger is locked by the bar crossing its notch so that it cannot be
moved.
In the Specification above referred to I described the use of a detent worked by
the armature of an electro-magnet, for the purpose of locking or unlocking the
interlocking handle by electrical communication from a distant station. I modify
the action of this detent by inaking it catch in a notch of a cam on the spindle of
the interlocking handle, making one side of the notch inclined and the other
square:
"
When the handle is in its normal position the detent armature is held by the
cam to the electro-magnet. On turning the handle the detent armature of the
magnet active, being held by its attraction does not interfere with the movement
of the cam; but if the magnet on the cessation of the electrical current ceases to
attract, the detent drops into the notch and so prevents the handle from being
turned. On turning the handle back the inclined edge of the notch moves the
detent armature again towards the magnet, so that no magnetic force is required
to attract the armature to its normal position.
When the detent is intended to act on the transmission of an electrical current
instead of acting on its cessation it is arranged to work in a slot of a can, having
the incline on the one side and the square face of the notch on the other side.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Hodgson in the Great Seal Patent Office on the 27th
September 1878.
CHARLES HODGSON, of Canterbury Road, Kilburn, in the County of Middlesex.
"IMPROVEMENTS IN INTERLOCKING APPARATUS FOR THE POINTS, AND SIGNALS, AND
TELEGRAPHIC BLOCK INSTRUMENTS OF RAILWAYS."
In the Specification of Letters Patent granted to me on the 31st January 1877,
No. 400, I described means of interlocking the points and signals of railways with
the telegraphic instruments used for communicating from station to station.
My present Invention relates to improvements in such apparatus, whereby I am
enabled to apply the interlocking gear in connection with telegraphic instruments
working with one conducting wire, without interfering with the ordinary use of
these instruments or with the use of the conducting wire for purposes of communi-
cation generally.
The instruments referred to usually have two operating keys generally in the
form of spring plungers which are pushed in to send a signal, and having sent it
rebound to their former position, the one of the two plungers signalling "line clear"
and the other "line blocked," and either capable of sounding a bell or other audible
signal. For working these plungers in accord with the interlocking gear, described
in the Specification above referred to, I fix on the spindle to which is attached the
handle for interlocking a two-armed lever, and I connect each of the aforesaid
plungers by a bell crank to a vertical rod linked to a pawl on each side of the sairl
spindle.
When the handle is turned in the one direction one of the lever arms by acting
on one of the pawls depresses one of the vertical rods, and so causes the one plunger
to be thrust inwards so as to send a signal; but when the handle has completed
its movement the arm of its lever escapes from the pawl and allows the plunger
to be moved outwards by its spring, the wire being thus left available for other
purposes.
When the handle is turned in the opposite direction the lever arm that formerly
acted escapes its pawl, but the other arm catching the other pawl acts on the other
plunger in like manner.
Fig. 1 represents a front view, and Fig. 2 a side view of this arrangement, the
front and side of the casing of the apparatus being supposed to be removed to shew
the internal construction.
A is the spindle of the handle for interlocking, as described in the Specification
above referred to. On this spindle I fix the two arms B, B'; C, C, are the two
plungers for signalling, connected to bell-crank levers D, D¹, from which rods d, d',
extend downwards one on each side of the spindle A. The lower ends of the rods
d, d', are respectively connected by pins working in slotted holes with pawls b, b¹,
the noses of which project forwards into the path of the arms B, B¹.
It will be seen that on turning the spindle A in the direction of the arrow the
one arm B will simply raise and escape the pawl b without affecting the plunger C;
but the other arm B¹ in descending will catch the nose of the pawl bi and draw
down the rod d³, moving the bell-crank lever D¹, and causing the plunger C" to be
thrust in giving its signal. In its continued descent the arın B' will escape the
nose of the pawl b', and the spring of the plunger C" will thereupon return it and
the parts connected with it to the position shewn in the Drawing. On now turning
back the spindle in the direction opposite to that of the arrow, B¹ will escape b¹, and
B will operate upon C.
To ensure the complete movement of A in either direction, and stop it when it is
complete, I provide the doubly inclined piece a, which is pressed down by a spring
so as to act on a pin on an arm of A.
In case either of the plungers C, C, should fail to spring back I provide on the
rods d, d, projections, such as is shewn at d, on which the arm B or B¹ acts when

page_text: it ascends, so as to push upwards the rod and so cause the plunger connected to it
to be drawn back.
A modification of this apparatus is shewn in front view at Fig. 3, and side view
at Fig. 4. In this case the spindle A has only one arm B, which acts in both its
ascent and its descent on the one pawl b, connected by a rod d with a three-armed
bell-crank lever D, which works either of the plungers C, C, according to the
direction in which A is turned. The pawl b is so arranged that after being raised
or depressed by B, as shewn by the dotted lines in Fig. 3, it escapes, and is caused
to return to its middle position by the spring of C or C¹. The pins of the two
arms of D work in holes in the plunger heads, slotted sufficiently far to permit the
one plunger to be thrust in without affecting the other, unless it shall have failed
to spring out, in which case it is drawn out by the motion of the bell crank.
Instead of making the interlocking handle work the plungers, as above described,
it may be made to interlock with them, but without moving them, in the following
manner-On the spindle of the interlocking handle I fix a cam, against which
bears a lever arm. From this arm a bar extends across the two spring plungers,
the bar being notched, and the plungers also being notched, so that in one position
of the handle both plungers facing notches in the bar are free to move, but the bar
itself cannot move until by pushing in one of the plungers & notch in it is brought
to face the bar. In the other position of the handle one of the plungers still
remains free, but the other plunger is locked by the bar crossing its notch so that
it cannot be moved.
Fig. 5 is a front view, and Fig. 6 a side view of this arrangement; c, c¹, are the
two plungers made with square rods notched at the side, as shewn in respect of C
in Fig. 5; G is a rod connected to the crank arm F, which is worked by the cam E
on the interlocking spindle A. The rod G is jointed at h, and its upper part is
drawn by a spring c against the side of the plunger rod C. As shewn in Fig. 5,
the spindle A cannot be turned in the direction of the arrow until by thrusting in
the plunger C' a notch on the side of its rod is brought to face the upper projec-
tion g' on the rod G. The spindle A being then turned the cam E acting on F
raises the rod G, causing both its projections g and g' to enter the notches in the
rods C, C¹, in which condition the plungers are locked. The upper projection g' is
by the complete up stroke of G moved past the rod O¹, again unlocking it; but the
lower projection g is made longer, so that while G is up it remains in the notch
of C, keeping it locked. On turning the spindle A back in the direction opposite
to that of the arrow a stud e on the cam E, acting against an arm f of the lever F
causes the rod G to descend, the spring c yielding so as to permit the upper jointed
part of the rod G to move aside sufficiently far for the projection g¹ to escape the
rod C¹, the lower end of the projection g₁ being sloped off for that purpose.
In the Specification above referred to I described the use of a detent worked by
the armature of an electro-magnet, for the purpose of locking or unlocking the
interlocking handle by electrical communication from a distant station. I modify
the action of this detent by making it catch in a notch of a cam on the spindle
of the interlocking handle, making one side of the notch inclined and the other
square.
When the handle is in its normal position the detent armature is held by the
cam to the electro-magnet. On turning the handle the detent armature, if the
magnet is active, being held by its attraction does not interfere with the movement
of the cam, but if the magnet on cessation of the electrical current ceases to attract,
the detent drops into the notch, and so prevents the handle from being turned.
On turning the handle back the inclined edge of the notch moves the detent
armature again towards the magnet, so that no niagnetic force is required to attract
the armature to its normal position.
Fig. 7 is a front view, and Fig. 8 a side view of this arrangement, Fig. 9 being
a side view of the contact-making portion of the apparatus. The interlocking
spindle A has an arm B, which works a plate C behind an opening c in the front of
the casing, so as to shew through this opening the words "line clear" or "line

page_text: blocked," or equivalent terms indicating the position of the spindle and of the levers
interlocked with it. On the spindle A there is also fixed the cam D, having at its
edge a notch d with its one end square and its other end sloped off; M is the
electro-magnet, having an armature E on a detent lever e, acted on by a spring F',
tending to detach the armature from the magnets. On turning the spindle in the
direction of the arrow, if the inagnet M be not rendered active by a current of
electricity transmitted through its coil, the lever e will drop into the notch & and
stop the motion of D when it comes against the square shoulder of the notch ; but
if the magnet be active, holding up the armature E, then the cam D can be turned
through its complete stroke. Again, on turning back the spindle A in the direction
opposite to that of the arrow, the lever e, if it should drop into the notch d, will be
raised by the incline at the end of d and rest on the edge of D, as shewn in Fig. 7.
On the spindle A are fixed two arms K, which by acting on a spring plunger L
serve to make or break the electrical contacts of the springs N, according as A is
moved in the one direction or the other. In the position shewn in the Figures all
the contacts are broken, but when A is turned in the direction of the arrow the
plunger L is depressed by the upper arm K, and the several springs N are brought
into contact. In this apparatus the detent lever e is arranged to stop the cam D
when there is a cessation of clectrical current through the coils of M; it may be
readily understood however that by arranging the detent e to work within a slot
in the cam D with a notch corresponding to d on its outer side, the detent e would
act as a stop when the armature is attracted upwards, that is to say, on the trans-
mission of an electrical current through the coils of M.
Having thus described the nature of my Invention, and in what manner the samo
is to be performed, I claim,-
First. Working the plungers of the block-signalling instruments of railways by
the movement of the spindle employed to effect the interlocking of the points and
signals with the telegraphic instruments, substantially as herein described with
reference to Figs. 1, 2, 3, and 4 of the accompanying Drawings, for the purposes
set forth.
Second. Interlocking the plungers of the block-signalling instruments with the
interlocking spindle referred to in the preceding claim, substantially as herein
described with reference to Figs. 5 and 6 of the accompanying Drawings.
Third. The use of apparatus, substantially as herein described with reference to
Figs. 7, 8, and 9 of the accompanying Drawings, whereby the interlocking spindle
above referred to is stopped in one direction of its movement by electrical action
froin a distance.
In witness whereof, I, the said Charles Hodgson, have hereunto set my hand
and seal, this Sixteenth day of September, in the year of our Lord One
thousand night hundred and seventy night
C. HODGSON. (LS.)