Improvements in Interlocking Railway Signals and Points.
Year: 1896

page_text: Date of Application, 28th Nov., 1896-Accepted, 23rd Jan., 1897
[Communicated from abroad by EDWARD WALLER STONEY, of the Madras Railway,
Madras, India, Civil Engineer, and SAMUEL TELFORD DUTTON, Junior, co
King Hamilton & Co., Dalhousie Square, Calcutta, India, Engineer.]
Improvements in Interlocking Railway Signals and Points.
1 SAMUEL TELFORD DUTTON of Marl Bank in the City of Worcester, Civil
Engineer do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement:-
My invention has reference to apparatus for detecting and locking facing points
worked by a ground lever and arranged in such a manner that should the points
be accidentally trailed through and forced open, the said appliances will become
disengaged and escape injury.
I am aware of a somewhat similar invention described in Samuel Telford Dutton's
Patent No. 13570 of 1888 in which the detector bolt is arranged to give way and
the signal goes to danger when the points are forced or run through.
I do not claim any method of automatically releasing the signal or bolt lock as
an abstract principle but having devised improved and more comprehensive
arrangements for securing and controlling the points with a similar automatic
safeguard I will proceed briefly to describe the same.
My invention comprises two methods of releasing the detecting bolt. In the first
the bolt gives way and disengages vertically. In the second the bolt gives way
and disengages horizontally. In either case the bolt can be drawn back and reset
by the action of a weight.
The points are worked by a ground lever with a weighted tumbler. This lever
may be worked independently or by detachable rods or wires from a distant cabin,
and is connected to an ordinary safety bar by a rod which is locked by the signal.
I will now describe my apparatus in detail reference being made to the accompanying
drawings.
Figs. 1 to 6 illustrate my point detector and release lock arranged to disengage
vertically.
A is a horizontal slide bar placed in a fixed frame and worked by the wire B
at one end and by the draw back weight C at the other. The end connected to
the wire B engages with a lower slide D by means of the catch or pair of stops E E
so that both slides are drawn when the wire is pulled. The lower slide is connected
to and operates the signal by the wire F.
The signal must be provided with sufficient counterbalance weight to draw the
lower slide back when released.
Under the upper slide A and within the frame is attached the detector bolt G
in the form of a longitudinal rib fitting a bevel notch H in a pair of cross bars I, I
connected to the switches and passing through the frame at right angles to the slide.
The notch H is opposite the end of the detector bolt G and allows the slide A to
be moved when the points are right for the signal.
In the event of the points being run through in the trailing direction and forced
open when the detector bolt is in the notch the upper slide is lifted by the bevel

page_text: notch acting as a wedge under the bolt G. Provision is made in the frame at J for
the clutch end of the upper slide to be thus lifted and disengaged from the lower one
which is then drawn back by the counterbalanco weight on the signal post and the
signal goes to danger.
A weight K fitting loosely a recess in the frame and resting on stops L L allows
the upper slide to travel freely when in gear but prevents the points from moving
and raising the slide too easily. The weight does not rest on the slide but the
slide cannot be raised to any exfent without lifting the weight as shown in Fig. 3.
The weight C must be sufficiently heavy to overcome the friction of the weight K
upon the slide so as to draw it back together with the wire B when the signal lever
is put back.
Recoupling of the catches E E may be effected automatically by the weight C
drawing the top catch over the lower one, or if preferred that operation may be
done by hand. In the latter caso the wheel & weight C may be dispensed with.
The lower slide D has a longitudinal rib or bolt M fitting a square notch Nin
a cross bar O connected to a ground lever for working the points and safety bar
which will be hereinafter described.
Normally the bolt M stands clear of the notch N allowing the ground lever and
safety bar to be worked and the points to be moved, but when the slides are drawn
forward and the signal is given the ground lever is locked by the bolt entering
the notch N and the points cannot then be moved by hand.
Figs. and 2. The upper slide may be drawn hack by a woighted lover or by
a weight in a well as shown in Figs. 1 and 2. The chain from the weight is taken
over a pulley wheel having two grooves with a gap P between the two through which
the chain crosses. By this arrangement the chain Qattached to the weight is clear
of the wire F on the lower slide.
Fig. 5. In cases where there are two signals one for either direction of the
points a duplicate set of slides may be carried in the same frame as shown in
Fig. 5 the notches R R being made to suit the travel of the switches.
Figs. 7 to 10 illustrato my point detector and release lock arranged to disengage
horizontally.
A is a horizontal slide bar placed in a fixed frame and worked by the wire B
at one end and by the drawback weight C at the other. The end connected to
the wire B engages with an upper slide D by means of stud pin and hook E E
so that both slides are drawn when the wire is pulled. The upper slide is connected
to and operates the signal by the wire F. The signal must be provided with
sufficient counterbalance weight to draw the upper slide back when released.
Figs. 7 and 8. Upon the lower slide and within the frame is attached the
detector holt G of square section placed so that when the slide is drawn forward
the bolt moves in front of a pair of cross bars I, I connected to the switches and
moving at right angles to the slide A. The ends of the cross bars are normally clear
of the detector bolt G and allow the slide A to be moved when the points are
right for the signal.
Figs. 8. and 9. In the event of the points being run throngh in the trailing
direction and forced open when the detector bolt G is in front of the cross bars I, I
the slide A is pushed out of gear with the upper slide as shown in Fig. 8. Provision
is made in the end of the frame at H Fig. 10 for this movement and when the slides
are thus disengaged the upper one is drawn back by the counterbalance weight on the
signal post and the signal goes to danger. The lower arm of a weighted lever J
keeps the slide A engaged with the slide D when the points are in their normal
position. The weighted lever does not grip the slide but rests against a stop K and
allows the slide to travel freely when in gear but prevents the points from moving and
throwing the apparatus out of gear too easily. This weight also assists in closing the
points after they have been inadvertently forced open.
Fig. 7. The weight C must be sufficiently heavy to draw the slide A and the wire B
when the signal lever is put back. Recoupling of the pin and hook E E may be
effected automatically by the weight C drawing the pin into the hook or if preferred

page_text: that operation may be done by hand. In the latter case the wheel and weight may
be dispensed with.
Figs. 7. 8. 9. The upper slide D has a longitudinal rib or bolt L fitting a square
notch M in a cross bar O connected to a ground lever for working the points and
safety bar which will be hereinafter described. Normally the bolt L stands clear of
the notch M allowing the ground lever and safety bar to be worked and the points to
be moved but when the slides are drawn forward and the signal given the ground
lever is locked by the bolt entering the notch M and the points cannot then be moved
by hand.
Fig. 10. In cases where there are two signals one for either direction of the points,
a duplicate set of slides may be carried in the same frame as shown in Fig. 10 the
notches P. P. being made to suit the travel of the switches.
Fig. 17. Instead of the weighted levers J J shown in Fig. 10 a spring may be placed
between the slides as shown at r in Fig. 17. The spring is carried in suitable
boxes as through which the disengaging slides A A pass. In this arrangement the
notches are cut so that the slides are pressed towards the centre of the frame when
the points are forced open.
Figs. 11, 12, 13, show the ground lever for working the points and safety bar.
The handle a works on a central pin b carried by two side frames cc. At each end
of its stroke the lever rests against the stops on the frame at d d and it may be
locked in either position by a suitable key or padlock at ee to prevent the points
heing reversed by any unauthorised person. The lower end of the handle or hand
lever is jointed to a rod f for working the safety bar. This rod is also connected to
the cross bar O (Fig. 1) in the detector frame and is there interlocked with the signals
as before explained. On one side of the hand lever is a weighted tumbler 9 working
loosely on pin b with projecting stops at hh by which it is moved when the lever
is reversed.
A pendant arm i carried on pin b between two lugs in the centre of the tumbler is
jointed at its lower end to the rod j for working the points. The weighted tumbler
bears against this arm at k and keeps the points closed. When the handlever is
reversed it turns the tumbler by means of the stop h far enough to tilt the weight
slightly beyond the vertical causing it to fall and bring the shoulder of the tumbler
to bear against the pendent arm as shown in Fig. 13 thus reversing the points
by the action of the weight being lifted without moving the hand lever or injuring
any part of the apparatus.
Fig. 14 is a general plan showing how the various parts of my invention may be
arranged and connected so as to work in the manner I have described and readily
fulfil their respective functions, but I do not confine myself to this precise
arrangement as it may be necessary in some cases to fix and connect the several
parts of the apparatus in different order to suit the place. In Fig. 14 the letters A
to Q and a to k refer to parts already described. A set of points is shown at S
connected by the rod j to the weighted tumbler g. The action of the weight p
keeps the points closed in the position shown but when the tumbler and weight are
reversed by the ground lever a the points are moved and pushed home the other way.
The rod is connected to the ground lever as shown in Figs. 11 and 14 and is
carried through the detector frame at o and interlocked with the signal slide by
the bolt M entering the notch N so that when the signal is pulled "off"
the ground lever is locked and when the ground lever is reversed the signal is
locked.
Fig. 16 shows the horizontal disengager as it would be fixed in place of that
shown in Fig. 14 for controlling the points S. When the signal wire F is pulled,
if the points are properly set both the slides D and A are drawn to the right and
the signal lowered as before explained & shown in Figs. 7 to 9. The points
are secured in two ways-first, by the bolt L entering the notch M in the rod O
of the ground lever thereby preventing the points being moved by hand and second
by the weighted lever J. If the points are trailed through from the closed road the
slide A is pushed out of gear by the cross bars I, I and the weight lifted.

page_text: Fig. 15 is a side view of an outside safety bar I mounted on rockers m m of an
ordinary description which lift the bar in the usual way when it is moved to and
fro by the crank n. This crank is coupled to the ground lever by a lug at o on the
rod so that the ground lever and the bar moves simultaneously.
As before explained the ground or hand lever must be reversed and the weighted
tumbler lifted and made to fall over before the points are moved. By this
arrangement a preliminary movement is imparted to the safety bar, so that when
the handlever is reversed it is lifted to its full height before the points are moved.
By a slight modification of the connexions and fittings as shown by dotted lines in
Fig. 14 the bar may be placed inside instead of outside the rail.
The combined action of the different parts of my invention will be more clearly
understood by further reference to the same drawing Fig. 14. The points are shown
standing for the left hand road and are firmly held in that position by the weights
p and g. The safety bar is down in its normal position and the notches H
and N in the cross bars stand opposite their respective bolts ready for the signal to
be given. When the wire B is pulled and the signal lowered the slides are drawn
forward causing the square bolt M to lock the ground lever and safety bar (dead)
and the bevel sided bolt G entering its notch in the cross bars tends to keep the points
closed. Should it happen that a train or vehicle trails through the points on the right
hand road when the points are bolted for the left, the cross rods I. I. allow the points
to give way or open by lifting and passing under the bevel sided bolt as shown in
Fig. 3 at the same time disengaging and putting the signal to danger. The other
cross rod although heavily weighted yields to the pressure also by lifting the weight
without moving the ground lever or safety bar. The weight p brings the points back
when the wheels have passed.
The ground lever can be worked and the points moved when the signal is at danger
and vehicles are clear of the safety bar. The ground lever and lockbar may also be
worked from a distance by rods or wires connected to the rod f Figs. 11, 12 and 14.
These connexions are detachable from the ground lever by withdrawing a bolt
when it is desired to work the apparatus by hand on the spot for shunting
purposes.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. A detector disengager and a safety bar connected to facing points and worked by
a ground lever with or without connections to a signal cabin in such a manner that
the points may be trailed through when bolted and forced open without injury to the
said apparatus as hereinbefore described and shown in Fig. 14.
2. The detector lock and vertically disengaging apparatus with the bevel sided
release bolt shown in Figs. 1 to 6.
3. The detector lock and disengaging apparatus with horizontal action to the
release bolt but without a "pivotted carrier' or sleeve shown in Figs. 7 to 10.
4. The combination of a safety bar with a ground lever and weighted tumbler
by means of which a movement is in parted to the said bar preliminary to that of
the points as shown in Figs. 14 and 15.
5. The use of a spring in lieu of a weighted lever to keep the slides in gear
substantially as shown in Fig. 17.
Dated this Twenty-seventh day of November 1896.
SAMUEL TELFORD DUTTON.