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

page_text: Date of Application, 31st Jan., 1888
Complete Specification Left, 14th Sept., 1888
Complete Specification Accepted, 12th Oct., 1888
PROVISIONAL SPECIFICATION.
An Improvement in Interlocking Apparatus for Railway Point and
Signal Levers.
We, JOHN SAXBY, and JOHN STINSON FARMER, 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 the interlocking apparatus for railway point and signal levers, known as tappet
and plunger-locking apparatus, each lever moves a rod or plunger having inclined
notches on its edge or edges into which enter stops or tappets on sliding bars that
move across these rods. When a tappet that is engaged in the notch of a plunger is
free to move laterally, the plunger when moved by the lever moves it aside causing
some other tappet on its sliding bar to engage in the notches of some others of the
plungers and so locking them and the levers to which they are linked; or when, on
the other hand a tappet is not free to be thus moved aside, the plunger that would
move it and the lever linked thereto are locked. In such apparatus it may happen
that when a lever is not moved fully over its plunger may present a notch in the
wrong place facing some tappet which can then be moved, into the notch, and thus a
lever, that should under those conditions be locked, may be moved, involving serious
danger. This invention has for its object to prevent accidents from this cause, by
ensuring that no lever of a set can be unlocked when any other of the levers is not
moved fully over. For this purpose the plungers of all the levers are provided with
notches on both edges so placed that only when the levers are at either end of their
stroke are these notches presented to a set of tappets arranged in a row across the
plungers, these tappets not being fixed all on one sliding bar but being each on a
short length of sliding bar and all these short lengths butting against each other.
When any lever is moved partly but not wholly over its plunger having thrust out a
pair of these tappets right and left and so having moved the whole row of them on
both its sides, keeps them in that position engaged in the notches of all the other
plungers and so locks all the other levers until it has completed its stroke and

page_text: presented its other notches for the tappets of the row. And thus generally according
to this invention as no plunger can be moved unless all the tappets of the row find
notches which can enter in all the other plungers, so no lever of the set can be
moved unless all the other levers are at the one end or the other of their respective
strokes.
ין
COMPLETE SPECIFICATION.
An Improvement in Interlocking Apparatus for Railway Point and
Signal Levers.
We, JOHN SAXBY, and JOHN STINSON FARMER, 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 the interlocking apparatus for railway point and signal levers, known as tappet
and plunger locking apparatus, each lover moves a rod or plunger having inclined
notches on its edge or edges, into which enter stops or tappets on sliding bars that
move across these rods. When a tappet that is engaged in the notch of a plunger is
free to move laterally, the plunger when moved by the lever moves it aside causing
some other tappets on its sliding bar to engage in the notches of some others of the
plungers and so locking them and the levers to which they are linked; or when on
the other hand a tappet is not free to be thus moved aside, the plunger that would
move it and the lever linked thereto are locked.
In such apparatus it may happen that when a lever is not moved fully over, its
plunger may present a notch in the wrong place facing some tappet which can then
be moved into the notch and thus a lever that should under those conditions be
locked, may be moved, involving serious danger.
This invention has for its object to prevent accidents from this cause, by ensuring
that no lever of a set can be unlocked when any other of the lovers is not moved
fully over. For this purpose, the plungers of all the levers are provided with
notches on their edges so placed that only when the levers are at either end of
their stroke are these notches presented to a set of tappets arranged in a row across
the plungers, these tappets not being fixed all on one sliding bar but being each

page_text: on a short length of sliding bar and all these short lengths butting against each
other.
When any lever is moved partly but not wholly over, its plunger having thrust
out one of these tappets or a pair of them, right and left, and so having moved the
whole row of them keeps them in that position engaged in the notches of all the
other plungers and so locks all the other levers until it has completed its stroke and
presented its other notches for the tappets of the row.
And thus, generally, according to this invention, as no plunger can be moved
unless all the tappets of the row find notches which they can enter in all the other
plungers, so no lever of the set can be moved unless all the other levers are at the one
end or the other of their respective strokes.
Fig. 1 of the accompanying drawings is a transverse section of a lever frame
shewing one of a set of levers A provided with tappet and plunger interlocking
apparatus of which Fig. 2 is a plan. Figs. 3, 4, 5 and 6 are transverse sections of
the locking gear at W, X, Y and Z (Fig. 2) respectively. Bare the plungers one of
which is jointed to each lever A, these plungers having at their edges notches for
tappets such as C D E arranged in the usual way, for example interlocking two
adjacent plungers B1 B2, D interlocking B' B, and E interlocking B' B³. One of the
plungers such as B₁, might be moved partly over in the direction of the arrow so as
to bring its notch for the tappet D into position to receive the tappet E, in which
case B would become unlocked.
This might involve serious danger, for then the lever controlled by B³ could be
moved when the lever controlled by B₁ is only partly moved, and thus, for example,
a signal could be given while a pair of points are partly open. In order to provide
against this danger, the plungers, besides having the notches for ordinary interlocking
tappets such as &DE, have each two notches for a set of additional tappets F, that
is to say a notch for each end of the stroke. The tappets F are not fixed on one
continuous transverse slide, but each projects up from a separate short slide, and
these slides butt against each other.
If now one of the plungers such as B were moved, it would thrust F2 and F3 to the
right causing them to engage in the notches of B3 B4 and it would prevent F' from
being thrust out of the notch of B¹ and thus B¹ B and B would be all locked
until B should be moved to the end of its stroke so as to present its other notchies f
to receive the fappets F' and F2.
In like manner, the partial movement of any one of the plungers locks the others
and these remain locked until that plunger completes its stroke.
In order that the ordinary tappets may be unable to enter the additional notches
described, these are preferably made of a different shape or cut only partly into the
thickness of the plungers, the special tappets F being made of forms to suit these
notches.
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 combination with tappet and plunger interlocking apparatus for railway point
and signal levers an additional set of tappets, engaging notches of the plungers
at each end of their stroke, substantially as and for the purpose herein set forth.
ABEL & IMRAY,
Agents for the Applicants.