Year: 1888

page_text: I HEINRICH LOUIS LÖFFLER of Bremen in the German Empire Merchant 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 :-
This Invention relates to an improved form of lock or latch for fastening doors and
the like whereby simplicity of construction certainty in action and great durability
are ensured A fastening provided with a counter weighted latching device according
to this invention differs from a lock or latch made in the usual way inasmuch as the
latch bolt is not acted on by a spring but is propelled by the action of its own weight
alone as hereinafter explained.
And in order that the said invention may be fully understood I shall now proceed
to describe the same and for that purpose shall refer to the several figures on the
annexed sheet of drawings the same letters of reference indicating corresponding
parts in all the figures.
Figures 7 and 8 illustrate the action of the two forms of latches most commonly
employed and which I will describe in the first place in order to show more clearly
in what respect the latch according to my invention differs from and is superior to
the latches of ordinary construction and arrangement.
In the case of the sliding latch illustrated in figure 8 the latch bolt is provided
with an incline a¹ which when the door is being closed moves in the direction of the
arrow 1 towards the striking plate 6. As the latter is a fixture and the latch is
capable of sliding in the direction of the arrow 2 it will readily be understood that
the lock or box of the latch moves in a line which crosses the line in which the latch
itself has to move.
In consequence of the shock or blow with which the latch meets
the striking plate b¹ the latch has a tendency to twist or place itself in the direction
of the dotted line 11 thus producing a considerable amount of friction and strain so
that the mechanism speedily gets out of order. In order to enable this latch to act
under favourable conditions it would be necessary to cause the pressure of the blow
or shock with which the latch a' meets the striking plate 61 on closing the door to be
exerted in the direction of the arrow 2.

page_text: In the case of pivoted latches such as the latch illustrated in figure 7 the same
defects are found as in the case of sliding latches in addition to the following dis-
advantage namely that when the door gradually sinks as all doors are liable to do after
a certain time the latch descends into the position indicated by the dotted lines in
figure 7 so that the end of the latch comes opposite the vertical part d or end of the
catch instead of meeting the incline n. The latch then strikes the vertical part d on
closing the door and in order to cause the latch to act properly it is necessary to take
off the catch and place it lower down, a proceeding which, when the catch is let into
the door post as usual, involves filling up the hollow above the catch with putty.
Moreover the screw holes in the catch no longer coincide with the holes in the door
post and the catch cannot be fixed in position with the same security as beforo owing
to the screws failing to bite or engage properly with the old and probably worn
holes in the woodwork. Under these conditions it is not surprising that by exerting
a certain amount of force on a door fitted with an ordinary latch after the catch has
been readjusted in this way the door can be readily burst open owing to the giving
way of the catch.
A further disadvantage of locks with ordinary latches is that they usually require a
spring to propel or depress the latch. As this spring is alternately compressed and
expanded very frequently (that is to say every time that the door is opened or
closed) it soon loses its elasticity or breaks and is always the first part that requires
repairs.
All these defects and disadvantages hereinbefore set forth are obviated by the
employment of the counter weighted latching device hereinafter described and
illustrated in figures 1 to 6 of the accompanying drawings which represent
oxamples of two modifications of the improved lock or latch constructed according
to this invention.
One of these modifications is illustrated in figures 1, 2, 3, 4, & 6 and the other
in figure 5.
Figure 1 represents a lock or latch according to this Invention in side elevation
partly in section showing the improved weighted latching device with the follower
and the follower spring.
Figure 2 is an end view of the lock or latch.
Figure 3 represents the lock or latch in plan shewing the weighted latching device.
Figure 4 illustrates the latching device apart.
Figure 5 illustrates a modified form of the latching device with a different form
or arrangement of the counter weight.
Figure 6 shows the end of the latching device inside the box or catch.
This lock or catch is provided with a weighted latching device composed
of the latching part proper and a weighted part or lever which can be
lifted in any suitable manner to disengage the latching device or latch proper.
In the arrangement illustrated in figure 1 the lock is provided for this purpose
with a follower a having an arm s. The weighted lever is pivoted on a
pin c and is somewhat in the form of a bell crank lever the shorter arm of which
forms the latching part whilst the longer arm forms the weighted part. The
end of the latch projects from the front plate of the lock box and is of such a shape
that its front side presents a semicircular ridge or projection e which extends in
inclined directions following two straight lines namely downwardly in the direction
of the line o--o figures 1 and 2 to the point and secondly forwards or outwards in
the direction of the line t t to the point as indicated in figure 3. When this elevation
or projection e on the latch end is pressed against the striking plate or catch the
end slides over the plate and is thus moved downwards and backwards into the lock
thus causing the weighted latch to turn on its centre pin c and assumes the
position indicated in dotted lines in figure 1 until it suddenly protrudes again and
engages with the catch. The leverage reckoning from the centre of the pine is less
at k than it is at the point z. As the resistance resulting from the weight of the
latch increases in proportion as it is pushed to one side by the striking plate the
weight is at its maximum when the latch is in the position indicated by the dotted
+

page_text: י
lines in figure 1 but the leverage is also increased in proportion so as to counteract
the effect of the increase in weight or resistance. The ridge or projection e and its
downward incline on the line o o is very favourably situated so that the projecting end
of the latch can slide back readily over the striking plate. On opening the door the
follower a is turned by means of the handle so as to elevate the arm s. which is acted
on by a spring p. The arms then lifts the weighted latch causing it to turn on
the pin c and move in the direction of the arrows in figures 1, 4, 5, thus drawing the
end of the latch back into the box of the lock. On shutting the door the latch
acts automatically. The spring pacts solely on the follower a. The latch itself is
entirely independent of the spring and its action is consequently the same whether
the lock be new or old. The weighted latch is provided with a rubber cushion or
buffer figure 4 to render it noiseless in action.
The part of the weighted latch which is situated inside the lock can be of any suit-
able shape but the projecting part is always substantially of the shape indicated.
Figure 5 represents a modified form of the latch suited for long and narrow locks.
The form of the projecting part is unchanged but the arm in this case does not form
the acting weight the projecting part 2 being provided with an extension / inside the
lock this extension as well as a part of the projecting end being made hollow. The
hollow in the extension is or may be loaded with lead, the hollow in the end being loft
empty and by those means the action of the counterweight is rendered more effective.
In this arrangement the rubber buffer is placed at the side and acts on the back of
the front plate.
The employment of these weighted latches enables the construction of the
catch to be simplified as indicated in figure 6. As the end of the latch slides over
the vertical side of the catch and projects between the horizontal sides the incline n
figure 7 of the catch or staple d is rendered unnecessary and at the same time the dis-
advantage herein before described in connection with the latch illustrated in figure 7
resulting from the sinking of the door is obviated. When the door sinks and Towers
the latch the latter simply has more play or clearance and its action is in no way
impaired.
The simplicity of the improved catch arrangement illustrated in figure 6 as
compared with the ordinary arrangement represented in figure 7 constitutes an im-
portant advantage as the catch or staple & figure 6 can be made with a plain piece of
Hat rod which merely requires to be bent to the form of a square staple this operation
admitting of being performed without heating the iron if required whereas the con-
struction of the catch illustrated in figure 7 necessitates a forging or casting operation
to form the incline n which is entirely dispensed with in the improved arrangement
described with reference to figure 6. A considerable saving of labour also results
from the absence of the spring and stud usually employed and which is unnecessary
with these weighted locks or latches and the locks provided with latching devices
according to this invention are thus enabled to be produced at a considerably cheaper
rate being at the same time rendered more durable and less liable to get out of
order.
Having now particularly described and ascertained the nature of this Invention and
in what manner the same is to be performed I declare that what I claim is
:
First In a lock or laich the arrangement of a latching device provided with a
counterweight so arranged that the end of the latching device is protruded by the
action of the weight substantially as hereinbefore described and illustrated in the
accompanying drawings.
Second: In combination with the weighted latching dovice referred to in the pre-
ceding claiming clause the arrangement of a pin c forming the axis of oscillation of
the latch so that the end of the latter may be caused either to protrude or to be
retracted by a partial rotation upon this axis substantially as hereinbefore described
and illustrated in the accompanying drawing.
:
Third In combination with the weighted latching device referred to in the first
and second claiming clauses the method of forming or shaping the latch end

page_text: whereby a semicircular ridge or projection is produced extending in the direction
indicated by the lines o-o and t t in order to facilitate the sliding action on the catch
and obtain a longer leverage at the end as the catch passes from k to z substantially
as herein before described.