Improvements in St
Year: 1894

page_text: Date of Application, 5th Feb., 1894
Complete Specification Left, 1st Dec., 1894-Accept-d, 2nd Feb.. 1895
I, EDWARD SYDNEY LUARD, of Malabar Hill, Bombay, India, First Assistant
Locomotive and Carriage Superintendent of the Bombay Baroda and Central India
Railway, do hereby declare the nature of this invention to be as follows:-
My invention relates to slam locks for use upon railway carriage and other doors
and it comprises improvements as hereinafter described.
According to my invention I combine with the bolt a follower which not only
serves to move back the bolt out of engagement with the keeper-plate but also to
lock the same when so withdrawn in a position in which only the bevelled end of
To effect such locking
the bolt projects through the edge plate of the lock case.
the follower may be provided with an independent locking-arm or catch adapted to
engage with some portion of the bolt or the arm which acts as the follower can
itself form the catch by adapting it to engage in a suitable notch.
In operating the lock the follower is turned by means of a handle so as to with-
draw the bolt completely within the lock-case and when the handle is released the
spring moves out the bolt until the latter is arrested by the catch. When the door
is shut the bevelled end of the bolt strikes the keeper-plate whereby the said bolt
is moved backwards sufficiently to allow the catch to disengage from the bolt under
the action of the spring so that when the door is completely closed the bolt can fly
forward in the usual manner.
I may arrange the same spring to operate both the follower and the bolt, or I
may use separate springs.
Improvements in St L
I, EDWARD SYDNEY LUARD, of Malabar Hill, Bombay, India, First Assistant
Locomotive and Carriage Superintendent of the Bombay Baroda and Central India
Railway, 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 relates to slam locks for use upon railway carriage and other doors
and it comprises improvements as hereinafter described.
According to my invention I combine with the bolt a follower which not only
serves to move back the bolt out of engagement with the keeper-plate but also to
lock the same when so withdrawn in a position in which only the bevelled end of
To effect such locking
the bolt projects through the edge plate of the lock case.
the follower is provided with an independent locking-arm or catch adapted to
engage with some portion of the bolt; or the arm which acts as the follower can
itself form the catch by adapting it to engage in a suitable notch.

page_text: In operating the lock the follower is turned by means of a handle so as to with-
draw the bolt completely within the lock-case and when the handle is released the
spring moves out the bolt until the latter is arrested by the catch. When the door
is shut to or slammed the bevelled end of the bolt strikes the keeper-plate whereby
the said bolt is moved backwards sufficiently to allow the catch to disengage from
the bolt under the action of the spring so that when the door is completely closed the
bolt can fly forward in the usual manner.
.I may arrange the samne spring to operate both the follower and the bolt, or I
may use separate springs.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawings, in which :-
Figure 1 is a sectional elevation of a slam-lock constructed according to the
invention, the said figure also shewing the keeper or striker plate:
Figures 2 and 3 are respectively sections on the lines 2-2 and 3-3 Figure 1:
Figures 4 and 5 are similar views to Figure 1 but shewing the lock bolt in
different positions; and,
Figure 6 is a section on the line 6-6, Figure 5:
Figures 7 and 8 are respectively a side elevation and a horizontal section of the
lock bolt:
Figures 9 and 10 are respectively a side elevation' and a vertical section of the
follower:
Figures 11 and 12 are sectional elevations illustrating different arrangements of
the invention:
Figure 13 is a sectional elevation illustrating a modification of the invention;
and,
Figure 14 is a horizontal section on the line 14-14 Figure 13:
Figure 15 is a similar view to Figure 13 but shewing the parts of the lock in a
different position :
Similar létters of reference indicate corresponding parts in the several figures.
a is the lock case; b the bolt which at one end slides through the case and which
is also slotted at to work upon a guide pin 62 fixed in the case; c the follower
which is mounted upon the spindle c¹ to which the handle is affixed and which
projects into a recess c² in the bolt, so that it will serve to operate the bolt in a well
known manner; d the spring or springs which normally tends or tend to push the
bolt out of the case; e the spring or springs which normally tends or tend to move
the follower to follow the bolt when projected out of the case and the keeper-
plate.
g is a projection formed upon the bolt and serving, by impinging against the
case a or against an independent strip, to limit the extent to which the bolt is
projected out of the case, and h is the locking arm or catch upon the follower,
which locking arm, after the follower has been moved to draw back the bolt within
the case, to permit of opening the door, allows the bolt when the handle is released
to return to such a position that the bevelled end of the said bolt will project
sufficiently far beyond the edge of the case to strike or come into contact with the
keeper-plate when the door is again shut, as shewn in Figures 5 and 6.
The operation of the lock shewn in Figures 1 to 6 is as follows:-Assume the
bolt to be in the position shewn in Figures 1 and 2, that is to say in the position in
which the bolt is in full engagement with the keeper-plate, if now the spindle c¹ of
the lock is turned, the bolt will be drawn entirely within the lock by the follower,
as shewn in Figure 4, so as to allow the door to be opened. When, however, the
handle of the lock is released the springs d (two being shewn) press the bolt
outwards until the tongue & forming the rear wall of the recess of the said bolt
comes into contact with the top of the locking arm upon the follower c, and arrests
the bolt in the intermediate position in which its bevelled end projects beyond the
edge of the door, as shewn in Figures 5 and 6, the said tongue thus forming a stop
or abutment. If, when the bolt is in this position, the door is slammed to, the
bevelled end of the bolt will strike against the keeper-plate f, as shewn in

page_text: Figure 6, and the said bolt will be moved backwardly to the position shewn in
dotted lines in Figure 5 against the pressure of the springs d, d thereby moving the
tongue 6 out of the way of the locking arm h. The follower c thus being free will
be moved forwards under the action of the spring e, so that the bolt b, when the
door is completely shut, is free to fly also forwards under the action of the
springs d, d to the position shewn in Figures 1 and 2 to lock the door.
In the modification of my invention shewn in Figure 11 the bolt is operated by
the spring which operates the follower, the movement of the spring being trans-
mitted to the bolt through the medium of a bell cranked lever i, as will be readily
understood by reference to the said figure, also the locking arm has the shape
of a hook designed to engage with a corresponding hook upon the bolt.
The arrangement of my invention shewn in Figure 12 is very similar to that
shewn in Figure 11, the essential difference being that the locking arm / upon the
follower is dispensed with, the said follower itself serving to hold the bolt in its
intermediate position by engaging in a notch j in the bolt as shewn.
In some cases I provide the arrangement shewn in Figures 13, 14 and 15 wherein
the bolt is divided, one part having a flush end, the other part forming a kind
of supplemental bolt having a bevelled end and which slides against the under-
side of the upper part of the bolt and between the follower and the lock case, the
recess in the bolt in which the follower engages being made of such a size as to
only permit the movement of the follower therein, which is thus caused to follow
the bolt without the aid of an independent spring.
At the inner end of the supplemental bolt which is marked k is a lug k¹ designed,
when the main or upper portion of the bolt is in its innermost position, to engage
above the locking arm upon the follower, as shewn in Figure 15, so as to hold the
said follower in a position to retain the bolt within the lock case.
When,
however, the door is slammed to, the supplemental bolt k is pushed in to the position
shewn in Figures 13 and 14, whereby, the lug k' being moved out of the way of the
locking arm h, the main bolt b is free to fly forward to its fully locked position, as
shewn in Figure 13, and so long as the supplemental bolt is retained in this inward
position the main bolt cannot be fixed in an unlocked position; when, however, on
the opening of the door the supplemental bolt is pushed outward under the action
of an independent spring, such as k², with which it is provided, the lug kl, when the
main bolt is drawn back, is free to pass above the projection to again hold the
bolt in its innermost position.
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 1
claim is :-
1. A slam lock in which the bolt is operated by a follower to draw it within the
lock case the said follower being provided with a locking arm or catch designed to
engage or come into contact with a stop or abutment on the bolt which stop serves
to hold the bolt in a position intermediate of its two extreme positions in such a
manner that when the bolt is pushed to its innermost position the locking arm upon
the follower will be disengaged from the bolt and allow the latter to move forward
under the action of a spring or springs, substantially as described.
2. The arrangement wherein the bolt is divided substantially as, described and
illustrated in Figures 13, 14 and 15 of the accompanying drawings.
3. The manufacture and use of slam locks substantially as described and illus
trated in Figures 1 to 10, Figure 11, Figure 12 and Figures 13 to 15 of the
accompanying drawings.
Dated the 30th day of November 1894.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.