An Improvement in Interlocking Apparatus for Railway Point and Signal Levers.
Year: 1888

page_text: Date of Application, 5th Jan., 1888
Complete Specification Left. 14th Sept., 1888
Complete Specification Accepted, 19th Oct., 1888
PROVISIONAL SPECIFICATION.
An Improvement in Interlocking Apparatus for Railway Point and
Signal Levers.
We JOHN SAXBY and JOHN STINSON FARMER both of Canterbury Road Kilburn in
the County of Middlesex, Engineers, and HUGH REID of No. 63 Great Northern Road
Derby, in the County of Derby, Signal Fitter, do hereby declare the nature of this
invention to be as follows:-
In many interlocking apparatus for railway point and signal levers, known as
tappet and plunger locking apparatus, there are rods or plungers, moved by the levers,
which have in their edges inclined or V shaped or rounded notches and there are
tappets or transverse slides with corresponding ends, so arranged that when a plunger
is moved by one lever it thrusts the cross slide out of its notch and into the notch of
another plunger if such notch happen to be presented to it thus locking the plunger of
another lever; or if no such notch he presented to receive the cross slide, the lever
that would move the cross slide is itself locked. This invention relates to means of
connecting the interlocking gear of this description to the spring catches of the levers
and of working the cross slides by the conjoint action of the levers and their spring
catches, so that locking is effected by raising the spring catch, before the movement of
the lever itself, and that unlocking cannot be effected until the lever is fully moved
over and its spring catch lowered.
For this purpose, we divide each plunger into two thicknesses or layers the one
layer lying close above the other. One of these layers is jointed to the main lever, the
other is jointed to a bell crank mounted on the lever and worked by the spring catch
of the lever. When the spring catch is down, holding the lever at either end of its
stroke, the notches in the two layers of the plunger are coincident, and a cross slide,
which is as thick as the two layers together can enter these notches. When the spring
catch is raised the notch of the plunger layer connected to it is moved, thrusting out
the cross slide and enabling the lever itself to be moved. When the lever is moved
fully over and the spring catch is lowered, but not till then, are the notches in the two
layers again coincident ready to receive a cross slide which may be moved by the
spring catch of another lever this other lever being thereby unlocked.
Dated this 5th day of January 1888.
ABEL & IMRAY,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
An Improvement in Interlocking Apparatus for Railway Point and
Signal Levers.
We, JOHN SAXBY, and JOHN STINSON FARMER, both of Canterbury Road,
Kilburn, in the County of Middlesex, Engineers, and HUGH REID of No. 63
Great Northern Road, Derby, in the County of Derby, Signal Fitter, 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-
In many interlocking apparatus for Railway point and signal levers, of the kind
known as tappet and plunger locking apparatus" there are sliding rods or plungers which
are moved by the levers and which have in their edges V shaped or rounded notches,
and there are transverse slides or tappets with corresponding V shaped or rounded
ends that fit into the notches of the plungers. When a lever is moved, its plunger
thrusts a tappet out of its notch and thus moves this tappet or a tappet on the
same transverse slide into the notch of another plunger if such notch happen to
be presented for its reception, and thus the lever to which that other plunger is con-
nected becomes locked. If however no notch is presented for the reception of the
tappet that has to be thrust out or for a tappet fixed on the same transverse slide, then
the plunger that tends to thrust out the tappet cannot do so and consequently the
lever to which that plunger is connected is locked. By suitably arranging tappets
in transverse slides in relation to notches of the plungers of a set of levers, theso
levers can be interlocked consistently with the conditions of the points and signals
which they work, as is well understood.
It may happen, however, that, when interlocking apparatus of this kind is employed,
one or other of the levers, though it is not fully home to either end of its stroke and
secured there by its spring catch, can unlock some other of the levers by presenting
a notch on its plunger to receive a tappet which should not then be received; and
serious accidents have been occasioned by such unlocking of levers which ought to
remain locked except when the operating lever is fully home and firmly held by the
engagement of its spring catch in the notch of the quadrant. This invention has for
its object to prevent the occurrence of such accidents by making sure that no lever
can be begun to be moved at all unless it is properly unlocked, and that no other
lever shall be unlocked by a lever so moved until the operating lever is home and
held firm by its spring catch.
.
For this purpose, the notched plunger belonging to each lever; instead of being
a single bar, is made in two layers or thicknesses, the one layer lying close over the
other, and both layers being equally notched; and the tappets on the transverse slides
are of depth equal to the two layers of the plungers, so that they can enter these notches
when the two layers coincide in position, but cannot enter when the one layer is so
far displaced along the other that the notches in the two layers no longer coincide in
position. This displacement of the two layers relatively to one another is effected by

page_text: the movement of the spring catch of the lever; and consequently there is no coinci-
dence of the notches of the two layers of any plunger except when the spring catch
is engaged at either end of the quadrant along which the lever is moved. From this
it follows, that, except when a lover is at either end of its stroke and held there by the
engagement of its spring catch, its plunger cannot present coincident notches to any
tappet, and consequently cannot unlock any lever to which that tappet is related.
The accompanying drawings shew several modified constructions and arrangements
of parts whereby this system of interlocking can be carried out in practice.
Fig. 1 is a side view and Fig. 2 is a front view, both partly in section of a lever frame;
Fig. 3 is a plan shewing the plungers and several of the tappets, and Fig. 4 is a part
side view to an enlarged scale shewing the connection of the lever and spring catch to
the two layers of plungers.
Figs. 5 and 6 are side views partly in section shewing modifications in the con-
nections to the two layers of plunger, Figs. 7, 8 and 9 are respectively a transverse
section, a longitudinal section and a plan shewing a special interlocking of three
plungers which will hereafter be described. In all the figures the same reference
letters are employed as far as possible to indicate corresponding parts.
A is one of the point or signal levers provided as usual with its spring catch B
engaging at each end of the stroke of the lever against a shoulder or in a notch of the
quadrant C. The spring catch rod D is extended downwards and is jointed to one
arm of a bell crank lever E as shewn in Fig. 1 or to one arm of a three armed lever E¹
as shewn in Fig. 5 or to the arms of two bell crank levers E2 E3 as shewn in Fig. 6.
The plunger belonging to each lever A consists of the two layers or thicknesses F
and G, which, as shewn in Fig. 1 are linked respectively to the lever A and to the
upright arm of the bell crank E, or as shown in Fig. 5 to the two upright arms of the
three armed lever E¹, or, as shewn in Fig. 6 to the upright arms of the two bell
cranks E³. Whichever of these connections be adopted, the effect of raising the
spring catch rod D so as to disengage the spring catch B from the quadrant (and
thereby to permit the movement of the lever A, is to displace the two layers F and G
relatively to one another, and thereby to make coincident notches in the edge of F
and G no longer coincident. Thus, as shewn in Fig. 4, the notch g, which when the
spring catch is down coincides with fis displaced by the raising of the spring catch as
indicated by the dotted lines at g¹.
Across the lines of plungers F are fitted to slide the tappet bars H which may be
either above the plungers F. G or below them, or both above and below them as shewn
in Fig. 1. On each of the transverse slides I are fixed the necessary tappets K which
can enter the notches of the plungers F. G or can be thrust out of them by the move-
ments of the plungers, when they are free to be so thrust out. For example, as shewn
in Fig. 3 the transverse slide H has two tappets, K' engaged in a notch of the
plunger F, and K facing a notch in the plunger F. In this condition F might be
moved in the direction of the arrow thrusting K out of its notch because K is free to
enter the notch of F2. But if F were moved so as to displace its notch from K², or if
the two layers F and G of F were relatively displaced by the raising of the spring
catch to which F belongs so that the notches presented fowards K² no longer coincide,
then as K² could not enter a notch in F the slide H could not be moved, the tappet Ki
could not be thrust out of the notch of F¹ and consequently the lever to which F¹
belongs would remain locked. Again assuming that the notch of F2 could receive the
tappet K, then if the spring catch of the lever to which F1 belongs were raised the
displacement of one of its layers would thrust K¹ out and would consequently engage K³
in the notch of F2 thus locking the lever to which I belongs. It will thus be seen
that the raising of the spring catch of any lever, before the lever itself begins to move,
locks all other levers that should be locked, and that, after moving a lever, there is no
unlocking until the spring catch of the moved lever is lowered to engage with the
quadrant.
In the special case of interlocking shewn in Figs. 7, 8 and 9 three plungers having
upper layers F F F and lower layers G³ G G are correlated by a tappet K which
has sloped ends meeting K³ K' and is fitted to slide horizontally in a vertically

page_text: sliding block L. The lower layer G₁ of the middle plunger has two sets of notches
indicated by the dotted lines M N. As shewn in Fig. 9 the plunger F³ is free to be
moved, but F is locked by the tappet K' unless the plunger be in such a position
that its notch M or N is presented immediately above the tappet K. In that case
F can be moved thrusting out the tappet K³ even if F presents no notch to
receive K³ the slope of K raising the tappet K' along with the slide L and the
plunger G being then locked by the engagement of K in its notch. The upper
plunger F has projecting down from it two studs n which prevent K from
rising when F is displaced by the movement of the spring catch of the lever to
which F belongs.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
In interlocking apparatus of the tappet and plunger kind for railway point and
signal levers, making each plunger in two layers or thicknesses so connected to
the lever and its spring catch that the inclined notches which move and receive
tappets coincide in the two layers only when the spring catch is down engaged
with the quadrant, substantially as and for the purpose herein set forth.
Dated this 14th day of September 1888.
ABEL & IMRAY,
Agents for the Applicants.